From b750101eb236130cf056c675997decbac904cc49 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 17:35:18 +0200 Subject: Adding upstream version 252.22. Signed-off-by: Daniel Baumann --- man/systemd.network.xml | 4940 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 4940 insertions(+) create mode 100644 man/systemd.network.xml (limited to 'man/systemd.network.xml') diff --git a/man/systemd.network.xml b/man/systemd.network.xml new file mode 100644 index 0000000..e1c050f --- /dev/null +++ b/man/systemd.network.xml @@ -0,0 +1,4940 @@ + + + + + + + + systemd.network + systemd + + + + systemd.network + 5 + + + + systemd.network + Network configuration + + + + network.network + + + + Description + + A plain ini-style text file that encodes network configuration for matching network + interfaces, used by + systemd-networkd8. + See systemd.syntax7 + for a general description of the syntax. + + The main network file must have the extension .network; other + extensions are ignored. Networks are applied to links whenever the links appear. + + The .network files are read from the files located in the system network + directories /usr/lib/systemd/network and + /usr/local/lib/systemd/network, the volatile runtime network directory + /run/systemd/network and the local administration network directory + /etc/systemd/network. All configuration files are collectively sorted and + processed in alphanumeric order, regardless of the directories in which they live. However, files + with identical filenames replace each other. It is recommended that each filename is prefixed with + a number (e.g. 10-eth0.network). Otherwise, the default + .network files or those generated by + systemd-network-generator.service8 + may take precedence over user configured files. Files in /etc/ have the highest + priority, files in /run/ take precedence over files with the same name under + /usr/. This can be used to override a system-supplied configuration file with + a local file if needed. As a special case, an empty file (file size 0) or symlink with the same + name pointing to /dev/null disables the configuration file entirely (it is + "masked"). + + Along with the network file foo.network, a "drop-in" directory + foo.network.d/ may exist. All files with the suffix + .conf from this directory will be merged in the alphanumeric order and parsed + after the main file itself has been parsed. This is useful to alter or add configuration settings, + without having to modify the main configuration file. Each drop-in file must have appropriate + section headers. + + In addition to /etc/systemd/network, drop-in .d + directories can be placed in /usr/lib/systemd/network or + /run/systemd/network directories. Drop-in files in + /etc/ take precedence over those in /run/ which in turn + take precedence over those in /usr/lib/. Drop-in files under any of these + directories take precedence over the main network file wherever located. + + + + [Match] Section Options + + The network file contains a [Match] section, which determines if a given network file may + be applied to a given interface; and a [Network] section specifying how the interface should be + configured. The first (in alphanumeric order) of the network files that matches a given interface + is applied, all later files are ignored, even if they match as well. + + A network file is said to match a network interface if all matches specified by the [Match] + section are satisfied. When a network file does not contain valid settings in [Match] section, then + the file will match all interfaces and systemd-networkd warns about that. Hint: + to avoid the warning and to make it clear that all interfaces shall be matched, add the following: + Name=* The following keys are accepted: + + + + + + + + + + + + Name= + + A whitespace-separated list of shell-style globs matching the device name, as exposed + by the udev property INTERFACE, or device's alternative names. If the + list is prefixed with a "!", the test is inverted. + + + + + WLANInterfaceType= + + A whitespace-separated list of wireless network type. Supported values are + ad-hoc, station, ap, + ap-vlan, wds, monitor, + mesh-point, p2p-client, p2p-go, + p2p-device, ocb, and nan. If the + list is prefixed with a "!", the test is inverted. + + + + + SSID= + + A whitespace-separated list of shell-style globs matching the SSID of the currently + connected wireless LAN. If the list is prefixed with a "!", the test is inverted. + + + + + BSSID= + + A whitespace-separated list of hardware address of the currently connected wireless + LAN. Use full colon-, hyphen- or dot-delimited hexadecimal. See the example in + MACAddress=. This option may appear more than once, in which case the + lists are merged. If the empty string is assigned to this option, the list is reset. + + + + + + + + + + + + + + + [Link] Section Options + + The [Link] section accepts the following keys: + + + + MACAddress= + + The hardware address to set for the device. + + + + + MTUBytes= + + The maximum transmission unit in bytes to set for the device. The usual suffixes K, M, + G, are supported and are understood to the base of 1024. + Note that if IPv6 is enabled on the interface, and the MTU is chosen below 1280 (the + minimum MTU for IPv6) it will automatically be increased to this value. + + + + + ARP= + + Takes a boolean. If set to true, the ARP (low-level Address Resolution Protocol) + for this interface is enabled. When unset, the kernel's default will be used. + For example, disabling ARP is useful when creating multiple MACVLAN or VLAN virtual + interfaces atop a single lower-level physical interface, which will then only serve as a + link/"bridge" device aggregating traffic to the same physical link and not participate in + the network otherwise. Defaults to unset. + + + + + Multicast= + + Takes a boolean. If set to true, the multicast flag on the device is enabled. Defaults + to unset. + + + + + AllMulticast= + + Takes a boolean. If set to true, the driver retrieves all multicast packets from the + network. This happens when multicast routing is enabled. Defaults to unset. + + + + + Promiscuous= + + Takes a boolean. If set to true, promiscuous mode of the interface is enabled. Defaults + to unset. + If this is set to false for the underlying link of a passthru mode + MACVLAN/MACVTAP, the virtual interface will be created with the nopromisc + flag set. + + + + + Unmanaged= + + Takes a boolean. When yes, no attempts are made to bring up or + configure matching links, equivalent to when there are no matching network files. Defaults to + no. + This is useful for preventing later matching network files from interfering with + certain interfaces that are fully controlled by other applications. + + + + + Group= + + Link groups are similar to port ranges found in managed switches. When network + interfaces are added to a numbered group, operations on all the interfaces from that group + can be performed at once. Takes an unsigned integer in the range 0…2147483647. Defaults to + unset. + + + + + RequiredForOnline= + + Takes a boolean or a minimum operational state and an optional maximum operational + state. Please see + networkctl1 + for possible operational states. When yes, the network is deemed required + when determining whether the system is online (including when running + systemd-networkd-wait-online). When no, the network is + ignored when determining the online state. When a minimum operational state and an optional + maximum operational state are set, yes is implied, and this controls the + minimum and maximum operational state required for the network interface to be considered + online. + + Defaults to yes when ActivationPolicy= is not + set, or set to up, always-up, or + bound. Defaults to no when + ActivationPolicy= is set to manual or + down. This is forced to no when + ActivationPolicy= is set to always-down. + + The network will be brought up normally (as configured by + ActivationPolicy=), but in the event that there is no address being + assigned by DHCP or the cable is not plugged in, the link will simply remain offline and be + skipped automatically by systemd-networkd-wait-online if + RequiredForOnline=no. + + + + + RequiredFamilyForOnline= + + Takes an address family. When specified, an IP address in the given family is deemed + required when determining whether the link is online (including when running + systemd-networkd-wait-online). Takes one of ipv4, + ipv6, both, or any. Defaults to + any. Note that this option has no effect if + RequiredForOnline=no, or if RequiredForOnline= + specifies a minimum operational state below degraded. + + + + + ActivationPolicy= + + Specifies the policy for systemd-networkd managing the link + administrative state. Specifically, this controls how systemd-networkd + changes the network device's IFF_UP flag, which is sometimes + controlled by system administrators by running e.g., + ip link set dev eth0 up or ip link set dev eth0 down, + and can also be changed with networkctl up eth0 or + networkctl down eth0. + + Takes one of up, always-up, + manual, always-down, down, + or bound. When manual, + systemd-networkd will not change the link's admin state automatically; + the system administrator must bring the interface up or down manually, as desired. When + up (the default) or always-up, or + down or always-down, + systemd-networkd will set the link up or down, respectively, when the + interface is (re)configured. When always-up or + always-down, systemd-networkd will set the link up or + down, respectively, any time systemd-networkd detects a change in the + administrative state. When BindCarrier= is also set, this is automatically + set to bound and any other value is ignored. + + When the policy is set to down or manual, the + default value of RequiredForOnline= is no. When the + policy is set to always-down, the value of + RequiredForOnline= forced to no. + + The administrative state is not the same as the carrier state, so using + always-up does not mean the link will never lose carrier. The link carrier + depends on both the administrative state as well as the network device's physical connection. + However, to avoid reconfiguration failures, when using always-up, + IgnoreCarrierLoss= is forced to true. + + + + + + + + + [Network] Section Options + + The [Network] section accepts the following keys: + + + + Description= + + A description of the device. This is only used for presentation purposes. + + + + + DHCP= + + Enables DHCPv4 and/or DHCPv6 client support. Accepts yes, + no, ipv4, or ipv6. Defaults to + no. + + Note that DHCPv6 will by default be triggered by Router Advertisements, if reception is + enabled, regardless of this parameter. By explicitly enabling DHCPv6 support here, the DHCPv6 + client will be started in the mode specified by the WithoutRA= setting in the + [DHCPv6] section, regardless of the presence of routers on the link, or what flags the routers + pass. See IPv6AcceptRA=. + + Furthermore, note that by default the domain name specified through DHCP is not used + for name resolution. See option below. + + See the [DHCPv4] or [DHCPv6] sections below for further configuration options for the + DHCP client support. + + + + + DHCPServer= + + Takes a boolean. If set to yes, DHCPv4 server will be started. + Defaults to no. Further settings for the DHCP server may be set in the + [DHCPServer] section described below. + + + + + LinkLocalAddressing= + + Enables link-local address autoconfiguration. Accepts , + , , and . An IPv6 link-local + address is configured when or . An IPv4 link-local + address is configured when or and when DHCPv4 + autoconfiguration has been unsuccessful for some time. (IPv4 link-local address + autoconfiguration will usually happen in parallel with repeated attempts to acquire a DHCPv4 + lease). + + Defaults to when KeepMaster= or + Bridge= is set or when the specified + MACVLAN=/MACVTAP= has Mode=passthru, + or otherwise. + + + + + IPv6LinkLocalAddressGenerationMode= + + Specifies how IPv6 link-local address is generated. Takes one of + eui64, none, stable-privacy and + random. When unset, stable-privacy is used if + IPv6StableSecretAddress= is specified, and if not, + eui64 is used. Note that if LinkLocalAddressing= is + no or ipv4, then + IPv6LinkLocalAddressGenerationMode= will be ignored. Also, even if + LinkLocalAddressing= is yes or ipv6, + setting IPv6LinkLocalAddressGenerationMode=none + disables to configure an IPv6 link-local address. + + + + + IPv6StableSecretAddress= + + Takes an IPv6 address. The specified address will be used as a stable secret for + generating IPv6 link-local address. If this setting is specified, and + IPv6LinkLocalAddressGenerationMode= is unset, then + IPv6LinkLocalAddressGenerationMode=stable-privacy is implied. + If this setting is not specified, and stable-privacy is set to + IPv6LinkLocalAddressGenerationMode=, + then a stable secret address will be generated from the local machine ID and the interface + name. + + + + + IPv4LLStartAddress= + + Specifies the first IPv4 link-local address to try. Takes an IPv4 address for example + 169.254.1.2, from the link-local address range: 169.254.0.0/16 except for 169.254.0.0/24 and + 169.254.255.0/24. This setting may be useful if the device should always have the same address + as long as there is no address conflict. When unset, a random address will be automatically + selected. Defaults to unset. + + + + + IPv4LLRoute= + + Takes a boolean. If set to true, sets up the route needed for non-IPv4LL hosts to + communicate with IPv4LL-only hosts. Defaults to false. + + + + + DefaultRouteOnDevice= + + Takes a boolean. If set to true, sets up the IPv4 default route bound to the interface. + Defaults to false. This is useful when creating routes on point-to-point interfaces. This is + equivalent to e.g. the following, + ip route add default dev veth99 + or, + [Route] +Gateway=0.0.0.0 + Currently, there are no way to specify e.g., the table for the route configured by this + setting. To configure the default route with such an additional property, please use the + following instead: + [Route] +Gateway=0.0.0.0 +Table=1234 + If you'd like to create an IPv6 default route bound to the interface, please use the + following: + [Route] +Gateway=:: +Table=1234 + + + + + LLMNR= + + Takes a boolean or resolve. When true, enables + Link-Local Multicast Name Resolution + on the link. When set to resolve, only resolution is enabled, but not host + registration and announcement. Defaults to true. This setting is read by + systemd-resolved.service8. + + + + + + MulticastDNS= + + Takes a boolean or resolve. When true, enables + Multicast DNS support on the link. + When set to resolve, only resolution is enabled, but not host or service + registration and announcement. Defaults to false. This setting is read by + systemd-resolved.service8. + + + + + + DNSOverTLS= + + Takes a boolean or opportunistic. When true, enables + DNS-over-TLS support on the link. + When set to opportunistic, compatibility with non-DNS-over-TLS servers is + increased, by automatically turning off DNS-over-TLS servers in this case. This option + defines a per-interface setting for + resolved.conf5's + global DNSOverTLS= option. Defaults to unset, and the global setting will + be used. This setting is read by + systemd-resolved.service8. + + + + + + DNSSEC= + + Takes a boolean or allow-downgrade. When true, enables + DNSSEC DNS validation support on the + link. When set to allow-downgrade, compatibility with non-DNSSEC capable + networks is increased, by automatically turning off DNSSEC in this case. This option defines + a per-interface setting for + resolved.conf5's + global DNSSEC= option. Defaults to unset, and the global setting will be + used. This setting is read by + systemd-resolved.service8. + + + + + + DNSSECNegativeTrustAnchors= + + A space-separated list of DNSSEC negative trust anchor domains. If specified and DNSSEC + is enabled, look-ups done via the interface's DNS server will be subject to the list of + negative trust anchors, and not require authentication for the specified domains, or anything + below it. Use this to disable DNSSEC authentication for specific private domains, that cannot + be proven valid using the Internet DNS hierarchy. Defaults to the empty list. This setting is + read by + systemd-resolved.service8. + + + + + + LLDP= + + Controls support for Ethernet LLDP packet reception. LLDP is a link-layer protocol + commonly implemented on professional routers and bridges which announces which physical port + a system is connected to, as well as other related data. Accepts a boolean or the special + value routers-only. When true, incoming LLDP packets are accepted and a + database of all LLDP neighbors maintained. If routers-only is set only + LLDP data of various types of routers is collected and LLDP data about other types of devices + ignored (such as stations, telephones and others). If false, LLDP reception is disabled. + Defaults to routers-only. Use + networkctl1 + to query the collected neighbor data. LLDP is only available on Ethernet links. See + EmitLLDP= below for enabling LLDP packet emission from the local system. + + + + + + EmitLLDP= + + Controls support for Ethernet LLDP packet emission. Accepts a boolean parameter or the + special values nearest-bridge, non-tpmr-bridge and + customer-bridge. Defaults to false, which turns off LLDP packet emission. + If not false, a short LLDP packet with information about the local system is sent out in + regular intervals on the link. The LLDP packet will contain information about the local + hostname, the local machine ID (as stored in + machine-id5) + and the local interface name, as well as the pretty hostname of the system (as set in + machine-info5). + LLDP emission is only available on Ethernet links. Note that this setting passes data + suitable for identification of host to the network and should thus not be enabled on + untrusted networks, where such identification data should not be made available. Use this + option to permit other systems to identify on which interfaces they are connected to this + system. The three special values control propagation of the LLDP packets. The + nearest-bridge setting permits propagation only to the nearest connected + bridge, non-tpmr-bridge permits propagation across Two-Port MAC Relays, + but not any other bridges, and customer-bridge permits propagation until + a customer bridge is reached. For details about these concepts, see + IEEE 802.1AB-2016. + Note that configuring this setting to true is equivalent to + nearest-bridge, the recommended and most restricted level of propagation. + See LLDP= above for an option to enable LLDP reception. + + + + + BindCarrier= + + A link name or a list of link names. When set, controls the behavior of the current + link. When all links in the list are in an operational down state, the current link is + brought down. When at least one link has carrier, the current interface is brought up. + + This forces ActivationPolicy= to be set to bound. + + + + + + Address= + + A static IPv4 or IPv6 address and its prefix length, separated by a + / character. Specify this key more than once to configure several + addresses. The format of the address must be as described in + inet_pton3. + This is a short-hand for an [Address] section only containing an Address key (see below). + This option may be specified more than once. + + If the specified address is 0.0.0.0 (for IPv4) or + :: (for IPv6), a new address range of the requested size is automatically + allocated from a system-wide pool of unused ranges. Note that the prefix length must be equal + or larger than 8 for IPv4, and 64 for IPv6. The allocated range is checked against all + current network interfaces and all known network configuration files to avoid address range + conflicts. The default system-wide pool consists of 192.168.0.0/16, 172.16.0.0/12 and + 10.0.0.0/8 for IPv4, and fd00::/8 for IPv6. This functionality is useful to manage a large + number of dynamically created network interfaces with the same network configuration and + automatic address range assignment. + + + + + Gateway= + + The gateway address, which must be in the format described in + inet_pton3. + This is a short-hand for a [Route] section only containing a Gateway= key. + This option may be specified more than once. + + + + + DNS= + + A DNS server address, which must be in the format described in + inet_pton3. + This option may be specified more than once. Each address can optionally take a port number + separated with :, a network interface name or index separated with + %, and a Server Name Indication (SNI) separated with #. + When IPv6 address is specified with a port number, then the address must be in the square + brackets. That is, the acceptable full formats are + 111.222.333.444:9953%ifname#example.com for IPv4 and + [1111:2222::3333]:9953%ifname#example.com for IPv6. If an empty string is + assigned, then the all previous assignments are cleared. This setting is read by + systemd-resolved.service8. + + + + + + Domains= + + A whitespace-separated list of domains which should be resolved using the DNS servers + on this link. Each item in the list should be a domain name, optionally prefixed with a tilde + (~). The domains with the prefix are called "routing-only domains". The + domains without the prefix are called "search domains" and are first used as search suffixes + for extending single-label hostnames (hostnames containing no dots) to become fully qualified + domain names (FQDNs). If a single-label hostname is resolved on this interface, each of the + specified search domains are appended to it in turn, converting it into a fully qualified + domain name, until one of them may be successfully resolved. + + Both "search" and "routing-only" domains are used for routing of DNS queries: look-ups + for hostnames ending in those domains (hence also single label names, if any "search domains" + are listed), are routed to the DNS servers configured for this interface. The domain routing + logic is particularly useful on multi-homed hosts with DNS servers serving particular private + DNS zones on each interface. + + The "routing-only" domain ~. (the tilde indicating definition of a + routing domain, the dot referring to the DNS root domain which is the implied suffix of all + valid DNS names) has special effect. It causes all DNS traffic which does not match another + configured domain routing entry to be routed to DNS servers specified for this interface. + This setting is useful to prefer a certain set of DNS servers if a link on which they are + connected is available. + + This setting is read by + systemd-resolved.service8. + "Search domains" correspond to the domain and search + entries in + resolv.conf5. + Domain name routing has no equivalent in the traditional glibc API, which has no concept of + domain name servers limited to a specific link. + + + + + DNSDefaultRoute= + + Takes a boolean argument. If true, this link's configured DNS servers are used for + resolving domain names that do not match any link's configured Domains= + setting. If false, this link's configured DNS servers are never used for such domains, and + are exclusively used for resolving names that match at least one of the domains configured on + this link. If not specified defaults to an automatic mode: queries not matching any link's + configured domains will be routed to this link if it has no routing-only domains configured. + + + + + + NTP= + + An NTP server address (either an IP address, or a hostname). This option may be + specified more than once. This setting is read by + systemd-timesyncd.service8. + + + + + + IPForward= + + Configures IP packet forwarding for the system. If enabled, incoming packets on any + network interface will be forwarded to any other interfaces according to the routing table. + Takes a boolean, or the values ipv4 or ipv6, which only + enable IP packet forwarding for the specified address family. This controls the + net.ipv4.ip_forward and net.ipv6.conf.all.forwarding + sysctl options of the network interface (see + IP Sysctl + for details about sysctl options). Defaults to no. + + Note: this setting controls a global kernel option, and does so one way only: if a + network that has this setting enabled is set up the global setting is turned on. However, + it is never turned off again, even after all networks with this setting enabled are shut + down again. + + To allow IP packet forwarding only between specific network interfaces use a firewall. + + + + + + IPMasquerade= + + Configures IP masquerading for the network interface. If enabled, packets forwarded + from the network interface will be appear as coming from the local host. Takes one of + ipv4, ipv6, both, or + no. Defaults to no. If enabled, this automatically sets + IPForward= to one of ipv4, ipv6 or + yes. + Note. Any positive boolean values such as yes or + true are now deprecated. Please use one of the values in the above. + + + + + IPv6PrivacyExtensions= + + Configures use of stateless temporary addresses that change over time (see + RFC 4941, + Privacy Extensions for Stateless Address Autoconfiguration in IPv6). Takes a boolean or the + special values prefer-public and kernel. When true, + enables the privacy extensions and prefers temporary addresses over public addresses. When + prefer-public, enables the privacy extensions, but prefers public + addresses over temporary addresses. When false, the privacy extensions remain disabled. When + kernel, the kernel's default setting will be left in place. Defaults to + no. + + + + + IPv6AcceptRA= + + Takes a boolean. Controls IPv6 Router Advertisement (RA) reception support for the + interface. If true, RAs are accepted; if false, RAs are ignored. When RAs are accepted, they + may trigger the start of the DHCPv6 client if the relevant flags are set in the RA data, or + if no routers are found on the link. The default is to disable RA reception for bridge + devices or when IP forwarding is enabled, and to enable it otherwise. Cannot be enabled on + bond devices and when link-local addressing is disabled. + + Further settings for the IPv6 RA support may be configured in the [IPv6AcceptRA] + section, see below. + + Also see + IP Sysctl + in the kernel documentation regarding accept_ra, but note that systemd's + setting of 1 (i.e. true) corresponds to kernel's setting of + 2. + + Note that kernel's implementation of the IPv6 RA protocol is always disabled, + regardless of this setting. If this option is enabled, a userspace implementation of the IPv6 + RA protocol is used, and the kernel's own implementation remains disabled, since + systemd-networkd needs to know all details supplied in the advertisements, + and these are not available from the kernel if the kernel's own implementation is used. + + + + + + IPv6DuplicateAddressDetection= + + Configures the amount of IPv6 Duplicate Address Detection (DAD) probes to send. When + unset, the kernel's default will be used. + + + + + IPv6HopLimit= + + Configures IPv6 Hop Limit. For each router that forwards the packet, the hop limit is + decremented by 1. When the hop limit field reaches zero, the packet is discarded. When unset, + the kernel's default will be used. + + + + + IPv4AcceptLocal= + + Takes a boolean. Accept packets with local source addresses. In combination with + suitable routing, this can be used to direct packets between two local interfaces over the + wire and have them accepted properly. When unset, the kernel's default will be used. + + + + + IPv4RouteLocalnet= + + Takes a boolean. When true, the kernel does not consider loopback addresses as martian + source or destination while routing. This enables the use of 127.0.0.0/8 for local routing + purposes. When unset, the kernel's default will be used. + + + + + IPv4ProxyARP= + + Takes a boolean. Configures proxy ARP for IPv4. Proxy ARP is the technique in which one + host, usually a router, answers ARP requests intended for another machine. By "faking" its + identity, the router accepts responsibility for routing packets to the "real" destination. + See RFC 1027. When unset, the + kernel's default will be used. + + + + + IPv6ProxyNDP= + + Takes a boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor Discovery Protocol) + is a technique for IPv6 to allow routing of addresses to a different destination when peers + expect them to be present on a certain physical link. In this case a router answers Neighbour + Advertisement messages intended for another machine by offering its own MAC address as + destination. Unlike proxy ARP for IPv4, it is not enabled globally, but will only send + Neighbour Advertisement messages for addresses in the IPv6 neighbor proxy table, which can + also be shown by ip -6 neighbour show proxy. systemd-networkd will control + the per-interface `proxy_ndp` switch for each configured interface depending on this option. + When unset, the kernel's default will be used. + + + + + IPv6ProxyNDPAddress= + + An IPv6 address, for which Neighbour Advertisement messages will be proxied. This + option may be specified more than once. systemd-networkd will add the + IPv6ProxyNDPAddress= entries to the kernel's IPv6 neighbor proxy table. + This setting implies IPv6ProxyNDP=yes but has no effect if + IPv6ProxyNDP= has been set to false. When unset, the kernel's default will + be used. + + + + + IPv6SendRA= + + Whether to enable or disable Router Advertisement sending on a link. Takes a boolean + value. When enabled, prefixes configured in [IPv6Prefix] sections and routes configured in + the [IPv6RoutePrefix] sections are distributed as defined in the [IPv6SendRA] section. If + DHCPPrefixDelegation= is enabled, then the delegated prefixes are also + distributed. See DHCPPrefixDelegation= setting and the [IPv6SendRA], + [IPv6Prefix], [IPv6RoutePrefix], and [DHCPPrefixDelegation] sections for more configuration + options. + + + + + DHCPPrefixDelegation= + + Takes a boolean value. When enabled, requests subnet prefixes on another link via the DHCPv6 + protocol or via the 6RD option in the DHCPv4 protocol. An address within each delegated prefix will + be assigned, and the prefixes will be announced through IPv6 Router Advertisement if + IPv6SendRA= is enabled. This behaviour can be configured in the + [DHCPPrefixDelegation] section. Defaults to disabled. + + + + + IPv6MTUBytes= + + Configures IPv6 maximum transmission unit (MTU). An integer greater than or equal to + 1280 bytes. When unset, the kernel's default will be used. + + + + + KeepMaster= + + Takes a boolean value. When enabled, the current master interface index will not be + changed, and BatmanAdvanced=, Bond=, + Bridge=, and VRF= settings are ignored. This may be + useful when a netdev with a master interface is created by another program, e.g. + systemd-nspawn1. + Defaults to false. + + + + + BatmanAdvanced= + Bond= + Bridge= + VRF= + + The name of the B.A.T.M.A.N. Advanced, bond, bridge, or VRF interface to add the link + to. See + systemd.netdev5. + + + + + + IPoIB= + IPVLAN= + IPVTAP= + MACsec= + MACVLAN= + MACVTAP= + Tunnel= + VLAN= + VXLAN= + Xfrm= + + The name of an IPoIB, IPVLAN, IPVTAP, MACsec, MACVLAN, MACVTAP, tunnel, VLAN, + VXLAN, or Xfrm to be created on the link. See + systemd.netdev5. + This option may be specified more than once. + + + + + ActiveSlave= + + Takes a boolean. Specifies the new active slave. The ActiveSlave= + option is only valid for following modes: active-backup, + balance-alb, and balance-tlb. Defaults to false. + + + + + PrimarySlave= + + Takes a boolean. Specifies which slave is the primary device. The specified device will + always be the active slave while it is available. Only when the primary is off-line will + alternate devices be used. This is useful when one slave is preferred over another, e.g. + when one slave has higher throughput than another. The PrimarySlave= + option is only valid for following modes: active-backup, + balance-alb, and balance-tlb. Defaults to false. + + + + + ConfigureWithoutCarrier= + + Takes a boolean. Allows networkd to configure a specific link even if it has no + carrier. Defaults to false. If enabled, and the IgnoreCarrierLoss= setting + is not explicitly set, then it is enabled as well. + + + + + IgnoreCarrierLoss= + + Takes a boolean or a timespan. When true, systemd-networkd retains + both the static and dynamic configuration of the interface even if its carrier is lost. When + false, systemd-networkd drops both the static and dynamic configuration of + the interface. When a timespan is specified, systemd-networkd waits for + the specified timespan, and ignores the carrier loss if the link regain its carrier within + the timespan. Setting 0 seconds is equivalent to no, and + infinite is equivalent to yes. + + Setting a finite timespan may be useful when e.g. in the following cases: + + + A wireless interface connecting to a network which has multiple access points with + the same SSID. + + + Enslaving a wireless interface to a bond interface, which may disconnect from the + connected access point and causes its carrier to be lost. + + + The driver of the interface resets when the MTU is changed. + + + + + When Bond= is specified to a wireless interface, defaults to 3 + seconds. When the DHCPv4 client is enabled and UseMTU= in the [DHCPv4] + section enabled, defaults to 5 seconds. Otherwise, defaults to the value specified with + ConfigureWithoutCarrier=. When ActivationPolicy= is set + to always-up, this is forced to yes, and ignored any + user specified values. + + + + + KeepConfiguration= + + Takes a boolean or one of static, dhcp-on-stop, + dhcp. When static, systemd-networkd + will not drop static addresses and routes on starting up process. When set to + dhcp-on-stop, systemd-networkd will not drop addresses + and routes on stopping the daemon. When dhcp, + the addresses and routes provided by a DHCP server will never be dropped even if the DHCP + lease expires. This is contrary to the DHCP specification, but may be the best choice if, + e.g., the root filesystem relies on this connection. The setting dhcp + implies dhcp-on-stop, and yes implies + dhcp and static. Defaults to + dhcp-on-stop when systemd-networkd is running in + initrd, yes when the root filesystem is a network filesystem, and + no otherwise. + + + + + + + [Address] Section Options + + An [Address] section accepts the following keys. Specify several [Address] sections to + configure several addresses. + + + + Address= + + As in the [Network] section. This setting is mandatory. Each [Address] section can + contain one Address= setting. + + + + + Peer= + + The peer address in a point-to-point connection. Accepts the same format as the + Address= setting. + + + + + Broadcast= + + Takes an IPv4 address or boolean value. The address must be in the format described in + inet_pton3. + If set to true, then the IPv4 broadcast address will be derived from the + Address= setting. If set to false, then the broadcast address will not be + set. Defaults to true, except for wireguard interfaces, where it default to false. + + + + + Label= + + Specifies the label for the IPv4 address. The label must be a 7-bit ASCII string with + a length of 1…15 characters. Defaults to unset. + + + + + PreferredLifetime= + + Allows the default "preferred lifetime" of the address to be overridden. Only three + settings are accepted: forever, infinity, which is the + default and means that the address never expires, and 0, which means that + the address is considered immediately "expired" and will not be used, unless explicitly + requested. A setting of is useful for addresses which + are added to be used only by a specific application, which is then configured to use them + explicitly. + + + + + Scope= + + The scope of the address, which can be global (valid everywhere on + the network, even through a gateway), link (only valid on this device, + will not traverse a gateway) or host (only valid within the device itself, + e.g. 127.0.0.1) or an integer in the range 0…255. Defaults to global. + + + + + + RouteMetric= + + The metric of the prefix route, which is pointing to the subnet of the configured IP + address, taking the configured prefix length into account. Takes an unsigned integer in the + range 0…4294967295. When unset or set to 0, the kernel's default value is used. This + setting will be ignored when AddPrefixRoute= is false. + + + + + HomeAddress= + + Takes a boolean. Designates this address the "home address" as defined in + RFC 6275. Supported only on IPv6. + Defaults to false. + + + + + DuplicateAddressDetection= + + Takes one of ipv4, ipv6, both, + or none. When ipv4, performs IPv4 Address Conflict + Detection. See RFC 5227. + When ipv6, performs IPv6 Duplicate Address Detection. See + RFC 4862. Defaults to + ipv4 for IPv4 link-local addresses, ipv6 for IPv6 + addresses, and none otherwise. + + + + + ManageTemporaryAddress= + + Takes a boolean. If true the kernel manage temporary addresses created from this one as + template on behalf of Privacy Extensions + RFC 3041. For this to become active, + the use_tempaddr sysctl setting has to be set to a value greater than zero. The given address + needs to have a prefix length of 64. This flag allows using privacy extensions in a manually + configured network, just like if stateless auto-configuration was active. Defaults to false. + + + + + + AddPrefixRoute= + + Takes a boolean. When true, the prefix route for the address is automatically added. + Defaults to true. + + + + + AutoJoin= + + Takes a boolean. Joining multicast group on ethernet level via + ip maddr command would not work if we have an Ethernet switch that does + IGMP snooping since the switch would not replicate multicast packets on ports that did not + have IGMP reports for the multicast addresses. Linux vxlan interfaces created via + ip link add vxlan or networkd's netdev kind vxlan have the group option + that enables them to do the required join. By extending ip address command + with option autojoin we can get similar functionality for openvswitch (OVS) + vxlan interfaces as well as other tunneling mechanisms that need to receive multicast traffic. + Defaults to no. + + + + + NetLabel=label + + + This setting provides a method for integrating static and dynamic network configuration into + Linux NetLabel subsystem rules, + used by Linux Security Modules + (LSMs) for network access control. The label, with suitable LSM rules, can be used to + control connectivity of (for example) a service with peers in the local network. At least with + SELinux, only the ingress can be controlled but not egress. The benefit of using this setting is + that it may be possible to apply interface independent part of NetLabel configuration at very early + stage of system boot sequence, at the time when the network interfaces are not available yet, with + netlabelctl8, + and the per-interface configuration with systemd-networkd once the interfaces + appear later. Currently this feature is only implemented for SELinux. + + The option expects a single NetLabel label. The label must conform to lexical restrictions of + LSM labels. When an interface is configured with IP addresses, the addresses and subnetwork masks + will be appended to the NetLabel + Fallback Peer Labeling rules. They will be removed when the interface is + deconfigured. Failures to manage the labels will be ignored. + + Warning: Once labeling is enabled for network traffic, a lot of LSM access control points in + Linux networking stack go from dormant to active. Care should be taken to avoid getting into a + situation where for example remote connectivity is broken, when the security policy hasn't been + updated to consider LSM per-packet access controls and no rules would allow any network + traffic. Also note that additional configuration with netlabelctl8 + is needed. + + Example: + [Address] +NetLabel=system_u:object_r:localnet_peer_t:s0 + + With the example rules applying for interface eth0, when the interface is + configured with an IPv4 address of 10.0.0.123/8, systemd-networkd performs the + equivalent of netlabelctl operation + + netlabelctl unlbl add interface eth0 address:10.0.0.0/8 label:system_u:object_r:localnet_peer_t:s0 + + and the reverse operation when the IPv4 address is deconfigured. The configuration can be used with + LSM rules; in case of SELinux to allow a SELinux domain to receive data from objects of SELinux + peer class. For example: + + type localnet_peer_t; +allow my_server_t localnet_peer_t:peer recv; + + The effect of the above configuration and rules (in absence of other rules as may be the case) is + to only allow my_server_t (and nothing else) to receive data from local subnet + 10.0.0.0/8 of interface eth0. + + + + + + + + [Neighbor] Section Options + + A [Neighbor] section accepts the following keys. The neighbor section adds a permanent, + static entry to the neighbor table (IPv6) or ARP table (IPv4) for the given hardware address on the + links matched for the network. Specify several [Neighbor] sections to configure several static + neighbors. + + + + Address= + + The IP address of the neighbor. + + + + + LinkLayerAddress= + + The link layer address (MAC address or IP address) of the neighbor. + + + + + + + [IPv6AddressLabel] Section Options + + An [IPv6AddressLabel] section accepts the following keys. Specify several [IPv6AddressLabel] + sections to configure several address labels. IPv6 address labels are used for address selection. + See RFC 3484. Precedence is managed by + userspace, and only the label itself is stored in the kernel. + + + + Label= + + The label for the prefix, an unsigned integer in the range 0…4294967294. 0xffffffff is + reserved. This setting is mandatory. + + + + + Prefix= + + IPv6 prefix is an address with a prefix length, separated by a slash + / character. This setting is mandatory. + + + + + + + [RoutingPolicyRule] Section Options + + An [RoutingPolicyRule] section accepts the following settings. Specify several + [RoutingPolicyRule] sections to configure several rules. + + + + TypeOfService= + + Takes a number between 0 and 255 that specifies the type of service to match. + + + + + From= + + Specifies the source address prefix to match. Possibly followed by a slash and the + prefix length. + + + + + To= + + Specifies the destination address prefix to match. Possibly followed by a slash and the + prefix length. + + + + + FirewallMark= + + Specifies the iptables firewall mark value to match (a number in the range + 1…4294967295). Optionally, the firewall mask (also a number between 1…4294967295) can be + suffixed with a slash (/), e.g., 7/255. + + + + + Table= + + Specifies the routing table identifier to lookup if the rule selector matches. Takes + one of predefined names default, main, and + local, and names defined in RouteTable= in + networkd.conf5, + or a number between 1 and 4294967295. Defaults to main. + + + + + Priority= + + Specifies the priority of this rule. Priority= is an integer in the + range 0…4294967295. Higher number means lower priority, and rules get processed in order of + increasing number. Defaults to unset, and the kernel will pick a value dynamically. + + + + + IncomingInterface= + + Specifies incoming device to match. If the interface is loopback, the rule only matches + packets originating from this host. + + + + + OutgoingInterface= + + Specifies the outgoing device to match. The outgoing interface is only available for + packets originating from local sockets that are bound to a device. + + + + + SourcePort= + + Specifies the source IP port or IP port range match in forwarding information base + (FIB) rules. A port range is specified by the lower and upper port separated by a dash. + Defaults to unset. + + + + + DestinationPort= + + Specifies the destination IP port or IP port range match in forwarding information base + (FIB) rules. A port range is specified by the lower and upper port separated by a dash. + Defaults to unset. + + + + + IPProtocol= + + Specifies the IP protocol to match in forwarding information base (FIB) rules. Takes IP + protocol name such as tcp, udp or + sctp, or IP protocol number such as 6 for + tcp or 17 for udp. Defaults to unset. + + + + + + InvertRule= + + A boolean. Specifies whether the rule is to be inverted. Defaults to false. + + + + + Family= + + Takes a special value ipv4, ipv6, or + both. By default, the address family is determined by the address + specified in To= or From=. If neither + To= nor From= are specified, then defaults to + ipv4. + + + + + User= + + Takes a username, a user ID, or a range of user IDs separated by a dash. Defaults to + unset. + + + + + SuppressPrefixLength= + + Takes a number N in the range 0…128 and rejects routing + decisions that have a prefix length of N or less. Defaults to + unset. + + + + + SuppressInterfaceGroup= + + Takes an integer in the range 0…2147483647 and rejects routing decisions that have + an interface with the same group id. It has the same meaning as + in ip rule. Defaults to unset. + + + + + Type= + + Specifies Routing Policy Database (RPDB) rule type. Takes one of + blackhole, unreachable or prohibit. + + + + + + + + [NextHop] Section Options + + The [NextHop] section is used to manipulate entries in the kernel's "nexthop" tables. The + [NextHop] section accepts the following settings. Specify several [NextHop] sections to configure + several hops. + + + + Id= + + The id of the next hop. Takes an integer in the range 1…4294967295. If unspecified, + then automatically chosen by kernel. + + + + + Gateway= + + As in the [Network] section. + + + + + Family= + + Takes one of the special values ipv4 or ipv6. + By default, the family is determined by the address specified in + Gateway=. If Gateway= is not specified, then defaults + to ipv4. + + + + + OnLink= + + Takes a boolean. If set to true, the kernel does not have to check if the gateway is + reachable directly by the current machine (i.e., attached to the local network), so that we + can insert the nexthop in the kernel table without it being complained about. Defaults to + no. + + + + + Blackhole= + + Takes a boolean. If enabled, packets to the corresponding routes are discarded + silently, and Gateway= cannot be specified. Defaults to + no. + + + + + Group= + + Takes a whitespace separated list of nexthop IDs. Each ID must be in the range + 1…4294967295. Optionally, each nexthop ID can take a weight after a colon + (id:weight). + The weight must be in the range 1…255. If the weight is not specified, then it is assumed + that the weight is 1. This setting cannot be specified with Gateway=, + Family=, Blackhole=. This setting can be specified + multiple times. If an empty string is assigned, then the all previous assignments are + cleared. Defaults to unset. + + + + + + + [Route] Section Options + + The [Route] section accepts the following settings. Specify several [Route] sections to + configure several routes. + + + + Gateway= + + Takes the gateway address or the special values _dhcp4 and + _ipv6ra. If _dhcp4 or _ipv6ra is + set, then the gateway address provided by DHCPv4 or IPv6 RA is used. + + + + + GatewayOnLink= + + Takes a boolean. If set to true, the kernel does not have to check if the gateway is + reachable directly by the current machine (i.e., attached to the local network), so that we + can insert the route in the kernel table without it being complained about. Defaults to + no. + + + + + Destination= + + The destination prefix of the route. Possibly followed by a slash and the prefix + length. If omitted, a full-length host route is assumed. + + + + + Source= + + The source prefix of the route. Possibly followed by a slash and the prefix length. If + omitted, a full-length host route is assumed. + + + + + Metric= + + The metric of the route. Takes an unsigned integer in the range 0…4294967295. Defaults + to unset, and the kernel's default will be used. + + + + + IPv6Preference= + + Specifies the route preference as defined in + RFC 4191 for Router Discovery + messages. Which can be one of low the route has a lowest priority, + medium the route has a default priority or high the + route has a highest priority. + + + + + Scope= + + The scope of the IPv4 route, which can be global, + site, link, host, or + nowhere: + + + global means the route can reach hosts more than one hop away. + + + + + site means an interior route in the local autonomous system. + + + + + link means the route can only reach hosts on the local network + (one hop away). + + + + host means the route will not leave the local machine (used for + internal addresses like 127.0.0.1). + + + + nowhere means the destination doesn't exist. + + + + For IPv4 route, defaults to host if Type= is + local or nat, and link if + Type= is broadcast, multicast, + anycast, or unicast. In other cases, + defaults to global. The value is not used for IPv6. + + + + + PreferredSource= + + The preferred source address of the route. The address must be in the format described + in + inet_pton3. + + + + + + Table= + + The table identifier for the route. Takes one of predefined names + default, main, and local, and names + defined in RouteTable= in + networkd.conf5, + or a number between 1 and 4294967295. The table can be retrieved using + ip route show table num. If unset and + Type= is local, broadcast, + anycast, or nat, then local is used. + In other cases, defaults to main. + + + + + Protocol= + + The protocol identifier for the route. Takes a number between 0 and 255 or the special + values kernel, boot, static, + ra and dhcp. Defaults to static. + + + + + + Type= + + Specifies the type for the route. Takes one of unicast, + local, broadcast, anycast, + multicast, blackhole, unreachable, + prohibit, throw, nat, and + xresolve. If unicast, a regular route is defined, i.e. + a route indicating the path to take to a destination network address. If + blackhole, packets to the defined route are discarded silently. If + unreachable, packets to the defined route are discarded and the ICMP + message "Host Unreachable" is generated. If prohibit, packets to the + defined route are discarded and the ICMP message "Communication Administratively Prohibited" + is generated. If throw, route lookup in the current routing table will + fail and the route selection process will return to Routing Policy Database (RPDB). Defaults + to unicast. + + + + + InitialCongestionWindow= + + The TCP initial congestion window is used during the start of a TCP connection. + During the start of a TCP session, when a client requests a resource, the server's initial + congestion window determines how many packets will be sent during the initial burst of data + without waiting for acknowledgement. Takes a number between 1 and 1023. Note that 100 is + considered an extremely large value for this option. When unset, the kernel's default + (typically 10) will be used. + + + + + InitialAdvertisedReceiveWindow= + + The TCP initial advertised receive window is the amount of receive data (in bytes) + that can initially be buffered at one time on a connection. The sending host can send only + that amount of data before waiting for an acknowledgment and window update from the + receiving host. Takes a number between 1 and 1023. Note that 100 is considered an extremely + large value for this option. When unset, the kernel's default will be used. + + + + + QuickAck= + + Takes a boolean. When true enables TCP quick ack mode for the route. When unset, the + kernel's default will be used. + + + + + FastOpenNoCookie= + + Takes a boolean. When true enables TCP fastopen without a cookie on a per-route basis. + When unset, the kernel's default will be used. + + + + + TTLPropagate= + + Takes a boolean. When true enables TTL propagation at Label Switched Path (LSP) egress. + When unset, the kernel's default will be used. + + + + + MTUBytes= + + The maximum transmission unit in bytes to set for the route. The usual suffixes K, M, + G, are supported and are understood to the base of 1024. + + + + + TCPAdvertisedMaximumSegmentSize= + + Specifies the Path MSS (in bytes) hints given on TCP layer. The usual suffixes K, M, G, + are supported and are understood to the base of 1024. An unsigned integer in the range + 1…4294967294. When unset, the kernel's default will be used. + + + + + TCPCongestionControlAlgorithm= + + Specifies the TCP congestion control algorithm for the route. Takes a name of the algorithm, + e.g. bbr, dctcp, or vegas. When unset, + the kernel's default will be used. + + + + + MultiPathRoute=address[@name] [weight] + + Configures multipath route. Multipath routing is the technique of using multiple + alternative paths through a network. Takes gateway address. Optionally, takes a network + interface name or index separated with @, and a weight in 1..256 for this + multipath route separated with whitespace. This setting can be specified multiple times. If + an empty string is assigned, then the all previous assignments are cleared. + + + + + NextHop= + + Specifies the nexthop id. Takes an unsigned integer in the range 1…4294967295. If set, + the corresponding [NextHop] section must be configured. Defaults to unset. + + + + + + + [DHCPv4] Section Options + + The [DHCPv4] section configures the DHCPv4 client, if it is enabled with the + DHCP= setting described above: + + + + + + + SendHostname= + + When true (the default), the machine's hostname (or the value specified with + Hostname=, described below) will be sent to the DHCP server. Note that the + hostname must consist only of 7-bit ASCII lower-case characters and no spaces or dots, and be + formatted as a valid DNS domain name. Otherwise, the hostname is not sent even if this option + is true. + + + + + Hostname= + + Use this value for the hostname which is sent to the DHCP server, instead of machine's + hostname. Note that the specified hostname must consist only of 7-bit ASCII lower-case + characters and no spaces or dots, and be formatted as a valid DNS domain name. + + + + + MUDURL= + + When configured, the specified Manufacturer Usage Description (MUD) URL will be sent + to the DHCPv4 server. Takes a URL of length up to 255 characters. A superficial verification + that the string is a valid URL will be performed. DHCPv4 clients are intended to have at most + one MUD URL associated with them. See + RFC 8520. + + MUD is an embedded software standard defined by the IETF that allows IoT device makers + to advertise device specifications, including the intended communication patterns for their + device when it connects to the network. The network can then use this to author a + context-specific access policy, so the device functions only within those parameters. + + + + + ClientIdentifier= + + The DHCPv4 client identifier to use. Takes one of , + or . If set to , the + MAC address of the link is used. If set to , an RFC4361-compliant Client + ID, which is the combination of IAID and DUID (see below), is used. If set to + , only DUID is used, this may not be RFC compliant, but some setups + may require to use this. Defaults to . + + + + + VendorClassIdentifier= + + The vendor class identifier used to identify vendor type and configuration. + + + + + UserClass= + + A DHCPv4 client can use UserClass option to identify the type or category of user or + applications it represents. The information contained in this option is a string that + represents the user class of which the client is a member. Each class sets an identifying + string of information to be used by the DHCP service to classify clients. Takes a + whitespace-separated list of strings. + + + + + DUIDType= + + Override the global DUIDType= setting for this network. See + networkd.conf5 + for a description of possible values. + + + + + DUIDRawData= + + Override the global DUIDRawData= setting for this network. See + networkd.conf5 + for a description of possible values. + + + + + IAID= + + The DHCP Identity Association Identifier (IAID) for the interface, a 32-bit unsigned + integer. + + + + + Anonymize= + + Takes a boolean. When true, the options sent to the DHCP server will follow the + RFC 7844 (Anonymity Profiles for + DHCP Clients) to minimize disclosure of identifying information. Defaults to false. + + This option should only be set to true when MACAddressPolicy= is set + to (see + systemd.link5). + + + When true, + ClientIdentifier=mac, + SendHostname=no, + Use6RD=no, + UseCaptivePortal=no, + UseMTU=no, + UseNTP=no, + UseSIP=no, and + UseTimezone=no + are implied and these settings in the .network file are silently ignored. Also, + Hostname=, + MUDURL=, + RequestOptions=, + SendOption=, + SendVendorOption=, + UserClass=, and + VendorClassIdentifier= + are silently ignored. + + With this option enabled DHCP requests will mimic those generated by Microsoft + Windows, in order to reduce the ability to fingerprint and recognize installations. This + means DHCP request sizes will grow and lease data will be more comprehensive than normally, + though most of the requested data is not actually used. + + + + + RequestOptions= + + Sets request options to be sent to the server in the DHCPv4 request options list. A + whitespace-separated list of integers in the range 1…254. Defaults to unset. + + + + + SendOption= + + Send an arbitrary raw option in the DHCPv4 request. Takes a DHCP option number, data + type and data separated with a colon + (option:type:value). + The option number must be an integer in the range 1…254. The type takes one of + uint8, uint16, uint32, + ipv4address, or string. Special characters in the data + string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is + specified, then all options specified earlier are cleared. Defaults to unset. + + + + + SendVendorOption= + + Send an arbitrary vendor option in the DHCPv4 request. Takes a DHCP option number, data + type and data separated with a colon + (option:type:value). + The option number must be an integer in the range 1…254. The type takes one of + uint8, uint16, uint32, + ipv4address, or string. Special characters in the data + string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is specified, + then all options specified earlier are cleared. Defaults to unset. + + + + + IPServiceType= + + Takes one of the special values none, CS6, or + CS4. When none no IP service type is set to the packet + sent from the DHCPv4 client. When CS6 (network control) or + CS4 (realtime), the corresponding service type will be set. Defaults to + CS6. + + + + + + + Label= + + Specifies the label for the IPv4 address received from the DHCP server. The label must + be a 7-bit ASCII string with a length of 1…15 characters. Defaults to unset. + + + + + UseDNS= + + When true (the default), the DNS servers received from the DHCP server will be used. + + + This corresponds to the option in + resolv.conf5. + + + + + + RoutesToDNS= + + When true, the routes to the DNS servers received from the DHCP server will be + configured. When UseDNS= is disabled, this setting is ignored. Defaults to + true. + + + + + UseNTP= + + When true (the default), the NTP servers received from the DHCP server will be used by + systemd-timesyncd.service. + + + + + RoutesToNTP= + + When true, the routes to the NTP servers received from the DHCP server will be + configured. When UseNTP= is disabled, this setting is ignored. Defaults to + true. + + + + + UseSIP= + + When true (the default), the SIP servers received from the DHCP server will be collected + and made available to client programs. + + + + + UseMTU= + + When true, the interface maximum transmission unit from the DHCP server will be used on + the current link. If MTUBytes= is set, then this setting is ignored. + Defaults to false. + + Note, some drivers will reset the interfaces if the MTU is changed. For such + interfaces, please try to use IgnoreCarrierLoss= with a short timespan, + e.g. 3 seconds. + + + + + UseHostname= + + When true (the default), the hostname received from the DHCP server will be set as the + transient hostname of the system. + + + + + UseDomains= + + Takes a boolean, or the special value . When true, the domain name + received from the DHCP server will be used as DNS search domain over this link, similarly to the + effect of the setting. If set to , the domain name + received from the DHCP server will be used for routing DNS queries only, but not for searching, + similarly to the effect of the setting when the argument is prefixed with + ~. Defaults to false. + + It is recommended to enable this option only on trusted networks, as setting this + affects resolution of all hostnames, in particular of single-label names. It is generally + safer to use the supplied domain only as routing domain, rather than as search domain, in + order to not have it affect local resolution of single-label names. + + When set to true, this setting corresponds to the option in + resolv.conf5. + + + + + + UseRoutes= + + When true (the default), the static routes will be requested from the DHCP server and + added to the routing table with a metric of 1024, and a scope of , + or , depending on the route's destination and + gateway. If the destination is on the local host, e.g., 127.x.x.x, or the same as the link's + own address, the scope will be set to . Otherwise if the gateway is null + (a direct route), a scope will be used. For anything else, scope + defaults to . + + + + + RouteMetric= + + Set the routing metric for routes specified by the DHCP server (including the prefix + route added for the specified prefix). Takes an unsigned integer in the range 0…4294967295. + Defaults to 1024. + + + + + RouteTable=num + + The table identifier for DHCP routes. Takes one of predefined names + default, main, and local, and names + defined in RouteTable= in + networkd.conf5, + or a number between 1…4294967295. + + When used in combination with VRF=, the VRF's routing table is + used when this parameter is not specified. + + + + + RouteMTUBytes= + + Specifies the MTU for the DHCP routes. Please see the [Route] section for further + details. + + + + + UseGateway= + + When true, the gateway will be requested from the DHCP server and added to the routing + table with a metric of 1024, and a scope of . When unset, the value + specified with UseRoutes= is used. + + + + + UseTimezone= + When true, the timezone received from the DHCP server will be set as timezone + of the local system. Defaults to false. + + + + Use6RD= + + When true, subnets of the received IPv6 prefix are assigned to downstream interfaces + which enables DHCPPrefixDelegation=. See also + DHCPPrefixDelegation= in the [Network] section, the [DHCPPrefixDelegation] + section, and RFC 5969. Defaults to + false. + + + + + FallbackLeaseLifetimeSec= + + Allows one to set DHCPv4 lease lifetime when DHCPv4 server does not send the lease + lifetime. Takes one of forever or infinity. If + specified, the acquired address never expires. Defaults to unset. + + + + + + + RequestBroadcast= + + Request the server to use broadcast messages before the IP address has been configured. + This is necessary for devices that cannot receive RAW packets, or that cannot receive packets + at all before an IP address has been configured. On the other hand, this must not be enabled + on networks where broadcasts are filtered out. + + + + + MaxAttempts= + + Specifies how many times the DHCPv4 client configuration should be attempted. Takes a + number or infinity. Defaults to infinity. Note that the + time between retries is increased exponentially, up to approximately one per minute, so the + network will not be overloaded even if this number is high. The default is suitable in most + circumstances. + + + + + ListenPort= + + Set the port from which the DHCP client packets originate. + + + + + DenyList= + + A whitespace-separated list of IPv4 addresses. Each address can optionally take a + prefix length after /. DHCP offers from servers in the list are rejected. + Note that if AllowList= is configured then DenyList= is + ignored. + + + + + AllowList= + + A whitespace-separated list of IPv4 addresses. Each address can optionally take a + prefix length after /. DHCP offers from servers in the list are accepted. + + + + + + SendRelease= + + When true, the DHCPv4 client sends a DHCP release packet when it stops. Defaults to + true. + + + + + SendDecline= + + A boolean. When true, systemd-networkd performs IPv4 Duplicate + Address Detection to the acquired address by the DHCPv4 client. If duplicate is detected, + the DHCPv4 client rejects the address by sending a DHCPDECLINE packet to + the DHCP server, and tries to obtain an IP address again. See + RFC 5227. Defaults to false. + + + + + NetLabel= + + This applies the NetLabel for the addresses received with DHCP, like + NetLabel= in [Address] section applies it to statically configured + addresses. See NetLabel= in [Address] section for more details. + + + + + + + [DHCPv6] Section Options + + The [DHCPv6] section configures the DHCPv6 client, if it is enabled with the + DHCP= setting described above, or invoked by the IPv6 Router Advertisement: + + + + + + + + MUDURL= + IAID= + DUIDType= + DUIDRawData= + RequestOptions= + + As in the [DHCPv4] section. + + + + + SendOption= + + As in the [DHCPv4] section, however because DHCPv6 uses 16-bit fields to store option + numbers, the option number is an integer in the range 1…65536. + + + + + SendVendorOption= + + Send an arbitrary vendor option in the DHCPv6 request. Takes an enterprise identifier, + DHCP option number, data type, and data separated with a colon + (enterprise identifier:option:type:value). + Enterprise identifier is an unsigned integer in the range 1…4294967294. The option number + must be an integer in the range 1…254. Data type takes one of uint8, + uint16, uint32, ipv4address, + ipv6address, or string. Special characters in the data + string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is + specified, then all options specified earlier are cleared. Defaults to unset. + + + + + UserClass= + + A DHCPv6 client can use User Class option to identify the type or category of user or + applications it represents. The information contained in this option is a string that + represents the user class of which the client is a member. Each class sets an identifying + string of information to be used by the DHCP service to classify clients. Special characters + in the data string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is + specified, then all options specified earlier are cleared. Takes a whitespace-separated list + of strings. Note that currently NUL bytes are not allowed. + + + + + VendorClass= + + A DHCPv6 client can use VendorClass option to identify the vendor that manufactured the + hardware on which the client is running. The information contained in the data area of this + option is contained in one or more opaque fields that identify details of the hardware + configuration. Takes a whitespace-separated list of strings. + + + + + PrefixDelegationHint= + + Takes an IPv6 address with prefix length in the same format as the + Address= in the [Network] section. The DHCPv6 client will include a prefix + hint in the DHCPv6 solicitation sent to the server. The prefix length must be in the range + 1…128. Defaults to unset. + + + + + RapidCommit= + + Takes a boolean. The DHCPv6 client can obtain configuration parameters from a DHCPv6 server + through a rapid two-message exchange (solicit and reply). When the rapid commit option is set by + both the DHCPv6 client and the DHCPv6 server, the two-message exchange is used. Otherwise, the + four-message exchange (solicit, advertise, request, and reply) is used. The two-message exchange + provides faster client configuration. See + RFC 3315 for details. + Defaults to true, and the two-message exchange will be used if the server support it. + + + + + + + UseAddress= + + When true (the default), the IP addresses provided by the DHCPv6 server will be + assigned. + + + + + UseDelegatedPrefix= + + When true (the default), the client will request the DHCPv6 server to delegate + prefixes. If the server provides prefixes to be delegated, then subnets of the prefixes are + assigned to the interfaces that have DHCPPrefixDelegation=yes. + See also the DHCPPrefixDelegation= setting in the [Network] section, + settings in the [DHCPPrefixDelegation] section, and + RFC 8415. + + + + + + UseDNS= + UseNTP= + UseHostname= + UseDomains= + NetLabel= + + As in the [DHCPv4] section. + + + + + + + WithoutRA= + + Allows DHCPv6 client to start without router advertisements's + managed or other configuration flag. Takes one of + no, solicit, or + information-request. If this is not specified, + solicit is used when DHCPPrefixDelegation= is enabled + and UplinkInterface=:self is specified in the [DHCPPrefixDelegation] + section. Otherwise, defaults to no, and the DHCPv6 client will be started + when an RA is received. See also the DHCPv6Client= setting in the + [IPv6AcceptRA] section. + + + + + + + [DHCPPrefixDelegation] Section Options + The [DHCPPrefixDelegation] section configures subnet prefixes of the delegated prefixes + acquired by a DHCPv6 client, or by a DHCPv4 client through the 6RD option on another interface. + The settings in this section are used only when the DHCPPrefixDelegation= + setting in the [Network] section is enabled. + + + + UplinkInterface= + + Specifies the name or the index of the uplink interface, or one of the special values + :self and :auto. When :self, the + interface itself is considered the uplink interface, and + WithoutRA=solicit is implied if the setting is not explicitly specified. + When :auto, the first link which acquired prefixes to be delegated from + the DHCPv6 or DHCPv4 server is selected. Defaults to :auto. + + + + + SubnetId= + + Configure a specific subnet ID on the interface from a (previously) received prefix + delegation. You can either set "auto" (the default) or a specific subnet ID (as defined in + RFC 4291, section + 2.5.4), in which case the allowed value is hexadecimal, from 0 to 0x7fffffffffffffff + inclusive. + + + + + Announce= + + Takes a boolean. When enabled, and IPv6SendRA= in [Network] section + is enabled, the delegated prefixes are distributed through the IPv6 Router Advertisement. + This setting will be ignored when the DHCPPrefixDelegation= setting is + enabled on the upstream interface. Defaults to yes. + + + + + Assign= + + Takes a boolean. Specifies whether to add an address from the delegated prefixes which + are received from the WAN interface by the DHCPv6 Prefix Delegation. When true (on LAN + interfce), the EUI-64 algorithm will be used by default to form an interface identifier from + the delegated prefixes. See also Token= setting below. Defaults to yes. + + + + + + Token= + + Specifies an optional address generation mode for assigning an address in each + delegated prefix. This accepts the same syntax as Token= in the + [IPv6AcceptRA] section. If Assign= is set to false, then this setting will + be ignored. Defaults to unset, which means the EUI-64 algorithm will be used. + + + + + ManageTemporaryAddress= + + As in the [Address] section, but defaults to true. + + + + + RouteMetric= + + The metric of the route to the delegated prefix subnet. Takes an unsigned integer in + the range 0…4294967295. When set to 0, the kernel's default value is used. Defaults to 256. + + + + + + NetLabel= + + This applies the NetLabel for the addresses received with DHCP, like + NetLabel= in [Address] section applies it to statically configured + addresses. See NetLabel= in [Address] section for more details. + + + + + + + [IPv6AcceptRA] Section Options + The [IPv6AcceptRA] section configures the IPv6 Router Advertisement (RA) client, if it is enabled + with the IPv6AcceptRA= setting described above: + + + + Token= + + Specifies an optional address generation mode for the Stateless Address + Autoconfiguration (SLAAC). The following values are supported: + + + + + + + The EUI-64 algorithm will be used to generate an address for that prefix. Only + supported by Ethernet or InfiniBand interfaces. + + + + + + + + An IPv6 address must be specified after a colon (:), and the + lower bits of the supplied address are combined with the upper bits of a prefix + received in a Router Advertisement (RA) message to form a complete address. Note + that if multiple prefixes are received in an RA message, or in multiple RA messages, + addresses will be formed from each of them using the supplied address. This mode + implements SLAAC but uses a static interface identifier instead of an identifier + generated by using the EUI-64 algorithm. Because the interface identifier is static, + if Duplicate Address Detection detects that the computed address is a duplicate + (in use by another node on the link), then this mode will fail to provide an address + for that prefix. If an IPv6 address without mode is specified, then + static mode is assumed. + + + + + + + + The algorithm specified in + RFC 7217 will be used to + generate interface identifiers. This mode can optionally take an IPv6 address + separated with a colon (:). If an IPv6 address is specified, + then an interface identifier is generated only when a prefix received in an RA + message matches the supplied address. + + + This mode can also optionally take a non-null UUID in the format which + sd_id128_from_string() accepts, e.g. + 86b123b969ba4b7eb8b3d8605123525a or + 86b123b9-69ba-4b7e-b8b3-d8605123525a. If a UUID is specified, the + value is used as the secret key to generate interface identifiers. If not specified, + then an application specific ID generated with the system's machine-ID will be used + as the secret key. See + sd-id1283, + sd_id128_from_string3, + and + sd_id128_get_machine3. + + + Note that the prefixstable algorithm uses both the interface + name and MAC address as input to the hash to compute the interface identifier, so + if either of those are changed the resulting interface identifier (and address) + will be changed, even if the prefix received in the RA message has not been + changed. + + + + + + If no address generation mode is specified (which is the default), or a received + prefix does not match any of the addresses provided in prefixstable + mode, then the EUI-64 algorithm will be used for Ethernet or InfiniBand interfaces, + otherwise prefixstable will be used to form an interface identifier for + that prefix. + + This setting can be specified multiple times. If an empty string is assigned, then + the all previous assignments are cleared. + + Examples: + Token=eui64 +Token=::1a:2b:3c:4d +Token=static:::1a:2b:3c:4d +Token=prefixstable +Token=prefixstable:2002:da8:1:: + + + + + UseDNS= + + When true (the default), the DNS servers received in the Router Advertisement will be used. + + This corresponds to the option in resolv.conf5. + + + + + UseDomains= + + Takes a boolean, or the special value route. When true, the domain name + received via IPv6 Router Advertisement (RA) will be used as DNS search domain over this link, + similarly to the effect of the setting. If set to + route, the domain name received via IPv6 RA will be used for routing DNS queries + only, but not for searching, similarly to the effect of the setting when + the argument is prefixed with ~. Defaults to false. + + It is recommended to enable this option only on trusted networks, as setting this affects resolution + of all hostnames, in particular of single-label names. It is generally safer to use the supplied domain + only as routing domain, rather than as search domain, in order to not have it affect local resolution of + single-label names. + + When set to true, this setting corresponds to the option in resolv.conf5. + + + + + RouteTable=num + + The table identifier for the routes received in the Router Advertisement. Takes one of + predefined names default, main, and local, + and names defined in RouteTable= in + networkd.conf5, + or a number between 1…4294967295. + + When used in combination with VRF=, the VRF's routing table is + used when this parameter is not specified. + + + + + RouteMetric= + + Set the routing metric for the routes received in the Router Advertisement. Takes an + unsigned integer in the range 0…4294967295. Defaults to 1024. + + + + + UseMTU= + + Takes a boolean. When true, the MTU received in the Router Advertisement will be + used. Defaults to true. + + + + + UseGateway= + + When true (the default), the router address will be configured as the default gateway. + + + + + + UseRoutePrefix= + + When true (the default), the routes corresponding to the route prefixes received in + the Router Advertisement will be configured. + + + + + UseAutonomousPrefix= + + When true (the default), the autonomous prefix received in the Router Advertisement will be used and take + precedence over any statically configured ones. + + + + + UseOnLinkPrefix= + + When true (the default), the onlink prefix received in the Router Advertisement will be + used and takes precedence over any statically configured ones. + + + + + RouterDenyList= + + A whitespace-separated list of IPv6 router addresses. Each address can optionally + take a prefix length after /. Any information advertised by the listed + router is ignored. + + + + + RouterAllowList= + + A whitespace-separated list of IPv6 router addresses. Each address can optionally + take a prefix length after /. Only information advertised by the listed + router is accepted. Note that if RouterAllowList= is configured then + RouterDenyList= is ignored. + + + + + PrefixDenyList= + + A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its + prefix length after /. IPv6 prefixes supplied via router advertisements + in the list are ignored. + + + + + PrefixAllowList= + + A whitespace-separated list of IPv6 prefixes. Each prefix can optionally take its + prefix length after /. IPv6 prefixes supplied via router advertisements + in the list are allowed. Note that if PrefixAllowList= is configured + then PrefixDenyList= is ignored. + + + + + RouteDenyList= + + A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take + its prefix length after /. IPv6 route prefixes supplied via router + advertisements in the list are ignored. + + + + + RouteAllowList= + + A whitespace-separated list of IPv6 route prefixes. Each prefix can optionally take + its prefix length after /. IPv6 route prefixes supplied via router + advertisements in the list are allowed. Note that if RouteAllowList= is + configured then RouteDenyList= is ignored. + + + + + DHCPv6Client= + + Takes a boolean, or the special value always. When true, the + DHCPv6 client will be started in solicit mode if the RA has the + managed flag or information-request mode if the RA + lacks the managed flag but has the + other configuration flag. If set to always, the + DHCPv6 client will be started in solicit mode when an RA is received, + even if neither the managed nor the + other configuration flag is set in the RA. This will be ignored when + WithoutRA= in the [DHCPv6] section is enabled, or + UplinkInterface=:self in the [DHCPPrefixDelegation] section is + specified. Defaults to true. + + + + + NetLabel= + + This applies the NetLabel for the addresses received with RA, like + NetLabel= in [Address] section applies it to statically configured + addresses. See NetLabel= in [Address] section for more details. + + + + + + + [DHCPServer] Section Options + The [DHCPServer] section contains settings for the DHCP server, if enabled via the + DHCPServer= option described above: + + + + + ServerAddress= + Specifies server address for the DHCP server. Takes an IPv4 address with prefix + length, for example 192.168.0.1/24. This setting may be useful when the link on + which the DHCP server is running has multiple static addresses. When unset, one of static addresses + in the link will be automatically selected. Defaults to unset. + + + + PoolOffset= + PoolSize= + + Configures the pool of addresses to hand out. The pool + is a contiguous sequence of IP addresses in the subnet configured for + the server address, which does not include the subnet nor the broadcast + address. PoolOffset= takes the offset of the pool + from the start of subnet, or zero to use the default value. + PoolSize= takes the number of IP addresses in the + pool or zero to use the default value. By default, the pool starts at + the first address after the subnet address and takes up the rest of + the subnet, excluding the broadcast address. If the pool includes + the server address (the default), this is reserved and not handed + out to clients. + + + + DefaultLeaseTimeSec= + MaxLeaseTimeSec= + + Control the default and maximum DHCP lease + time to pass to clients. These settings take time values in seconds or + another common time unit, depending on the suffix. The default + lease time is used for clients that did not ask for a specific + lease time. If a client asks for a lease time longer than the + maximum lease time, it is automatically shortened to the + specified time. The default lease time defaults to 1h, the + maximum lease time to 12h. Shorter lease times are beneficial + if the configuration data in DHCP leases changes frequently + and clients shall learn the new settings with shorter + latencies. Longer lease times reduce the generated DHCP + network traffic. + + + + UplinkInterface= + Specifies the name or the index of the uplink interface, or one of the special + values :none and :auto. When emitting DNS, NTP, or SIP + servers is enabled but no servers are specified, the servers configured in the uplink interface + will be emitted. When :auto, the link which has a default gateway with the + highest priority will be automatically selected. When :none, no uplink + interface will be selected. Defaults to :auto. + + + + EmitDNS= + DNS= + + EmitDNS= takes a boolean. Configures whether the DHCP leases + handed out to clients shall contain DNS server information. Defaults to yes. + The DNS servers to pass to clients may be configured with the DNS= option, + which takes a list of IPv4 addresses, or special value _server_address which + will be converted to the address used by the DHCP server. + + If the EmitDNS= option is enabled but no servers configured, the + servers are automatically propagated from an "uplink" interface that has appropriate servers + set. The "uplink" interface is determined by the default route of the system with the highest + priority. Note that this information is acquired at the time the lease is handed out, and does + not take uplink interfaces into account that acquire DNS server information at a later point. + If no suitable uplink interface is found the DNS server data from + /etc/resolv.conf is used. Also, note that the leases are not refreshed if + the uplink network configuration changes. To ensure clients regularly acquire the most current + uplink DNS server information, it is thus advisable to shorten the DHCP lease time via + MaxLeaseTimeSec= described above. + + This setting can be specified multiple times. If an empty string is specified, then all + DNS servers specified earlier are cleared. + + + + EmitNTP= + NTP= + EmitSIP= + SIP= + EmitPOP3= + POP3= + EmitSMTP= + SMTP= + EmitLPR= + LPR= + + Similar to the EmitDNS= and DNS= settings + described above, these settings configure whether and what server information for the indicate + protocol shall be emitted as part of the DHCP lease. The same syntax, propagation semantics and + defaults apply as for EmitDNS= and DNS=. + + + + EmitRouter= + Router= + + The EmitRouter= setting takes a boolean value, and configures + whether the DHCP lease should contain the router option. The Router= setting + takes an IPv4 address, and configures the router address to be emitted. When the + Router= setting is not specified, then the server address will be used for + the router option. When the EmitRouter= setting is disabled, the + Router= setting will be ignored. The EmitRouter= setting + defaults to true, and the Router= setting defaults to unset. + + + + + EmitTimezone= + Timezone= + + Takes a boolean. Configures whether the DHCP leases handed out + to clients shall contain timezone information. Defaults to yes. The + Timezone= setting takes a timezone string + (such as Europe/Berlin or + UTC) to pass to clients. If no explicit + timezone is set, the system timezone of the local host is + propagated, as determined by the + /etc/localtime symlink. + + + + BootServerAddress= + + + Takes an IPv4 address of the boot server used by e.g. PXE boot systems. When specified, this + address is sent in the field of the DHCP message header. See RFC 2131 for more details. Defaults to + unset. + + + + + BootServerName= + + + Takes a name of the boot server used by e.g. PXE boot systems. When specified, this name is + sent in the DHCP option 66 ("TFTP server name"). See RFC 2132 for more details. Defaults to + unset. + + Note that typically setting one of BootServerName= or + BootServerAddress= is sufficient, but both can be set too, if desired. + + + + + BootFilename= + + + Takes a path or URL to a file loaded by e.g. a PXE boot loader. When specified, this path is + sent in the DHCP option 67 ("Bootfile name"). See RFC 2132 for more details. Defaults to + unset. + + + + + SendOption= + + Send a raw option with value via DHCPv4 server. Takes a DHCP option number, data type + and data (option:type:value). + The option number is an integer in the range 1…254. The type takes one of uint8, + uint16, uint32, ipv4address, ipv6address, or + string. Special characters in the data string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is specified, + then all options specified earlier are cleared. Defaults to unset. + + + + + SendVendorOption= + + Send a vendor option with value via DHCPv4 server. Takes a DHCP option number, data type + and data (option:type:value). + The option number is an integer in the range 1…254. The type takes one of uint8, + uint16, uint32, ipv4address, or + string. Special characters in the data string may be escaped using + C-style + escapes. This setting can be specified multiple times. If an empty string is specified, + then all options specified earlier are cleared. Defaults to unset. + + + + BindToInterface= + + Takes a boolean value. When yes, DHCP server socket will be bound + to its network interface and all socket communication will be restricted to this interface. + Defaults to yes, except if RelayTarget= is used (see below), + in which case it defaults to no. + + + + RelayTarget= + + Takes an IPv4 address, which must be in the format described in + inet_pton3. + Turns this DHCP server into a DHCP relay agent. See RFC 1542. + The address is the address of DHCP server or another relay agent to forward DHCP messages to and from. + + + + RelayAgentCircuitId= + + Specifies value for Agent Circuit ID suboption of Relay Agent Information option. + Takes a string, which must be in the format string:value, + where value should be replaced with the value of the suboption. + Defaults to unset (means no Agent Circuit ID suboption is generated). + Ignored if RelayTarget= is not specified. + + + + RelayAgentRemoteId= + + Specifies value for Agent Remote ID suboption of Relay Agent Information option. + Takes a string, which must be in the format string:value, + where value should be replaced with the value of the suboption. + Defaults to unset (means no Agent Remote ID suboption is generated). + Ignored if RelayTarget= is not specified. + + + + + + + + [DHCPServerStaticLease] Section Options + The [DHCPServerStaticLease] section configures a static DHCP lease to assign a + fixed IPv4 address to a specific device based on its MAC address. This section can be specified multiple + times. + + + + MACAddress= + + The hardware address of a device to match. This key is mandatory. + + + + Address= + + The IPv4 address that should be assigned to the device that was matched with + MACAddress=. This key is mandatory. + + + + + + [IPv6SendRA] Section Options + The [IPv6SendRA] section contains settings for sending IPv6 Router Advertisements and whether + to act as a router, if enabled via the IPv6SendRA= option described above. IPv6 + network prefixes or routes are defined with one or more [IPv6Prefix] or [IPv6RoutePrefix] sections. + + + + + + Managed= + OtherInformation= + + Takes a boolean. Controls whether a DHCPv6 server is used to acquire IPv6 + addresses on the network link when Managed= + is set to true or if only additional network + information can be obtained via DHCPv6 for the network link when + OtherInformation= is set to + true. Both settings default to + false, which means that a DHCPv6 server is not being + used. + + + + RouterLifetimeSec= + + Takes a timespan. Configures the IPv6 router lifetime in seconds. The value must be 0 + seconds, or between 4 seconds and 9000 seconds. When set to 0, the host is not acting as a router. + Defaults to 1800 seconds (30 minutes). + + + + + RouterPreference= + + Configures IPv6 router preference if + RouterLifetimeSec= is non-zero. Valid values are + high, medium and + low, with normal and + default added as synonyms for + medium just to make configuration easier. See + RFC 4191 + for details. Defaults to medium. + + + + UplinkInterface= + Specifies the name or the index of the uplink interface, or one of the special + values :none and :auto. When emitting DNS servers or + search domains is enabled but no servers are specified, the servers configured in the uplink + interface will be emitted. When :auto, the value specified to the same + setting in the [DHCPPrefixDelegation] section will be used if + DHCPPrefixDelegation= is enabled, otherwise the link which has a default + gateway with the highest priority will be automatically selected. When :none, + no uplink interface will be selected. Defaults to :auto. + + + + EmitDNS= + DNS= + + DNS= specifies a list of recursive DNS server IPv6 addresses + that are distributed via Router Advertisement messages when EmitDNS= is true. + DNS= also takes special value _link_local; in that case + the IPv6 link-local address is distributed. If DNS= is empty, DNS servers are + read from the [Network] section. If the [Network] section does not contain any DNS servers + either, DNS servers from the uplink interface specified in UplinkInterface= + will be used. When EmitDNS= is false, no DNS server information is sent in + Router Advertisement messages. EmitDNS= defaults to true. + + + + EmitDomains= + Domains= + + A list of DNS search domains distributed via Router Advertisement messages when + EmitDomains= is true. If Domains= is empty, DNS search + domains are read from the [Network] section. If the [Network] section does not contain any DNS + search domains either, DNS search domains from the uplink interface specified in + UplinkInterface= will be used. When EmitDomains= is false, + no DNS search domain information is sent in Router Advertisement messages. + EmitDomains= defaults to true. + + + + DNSLifetimeSec= + + Lifetime in seconds for the DNS server addresses listed in + DNS= and search domains listed in Domains=. Defaults to + 3600 seconds (one hour). + + + + + + + [IPv6Prefix] Section Options + One or more [IPv6Prefix] sections contain the IPv6 prefixes that are announced via Router + Advertisements. See RFC 4861 for further + details. + + + + + AddressAutoconfiguration= + OnLink= + + Takes a boolean to specify whether IPv6 addresses can be + autoconfigured with this prefix and whether the prefix can be used for + onlink determination. Both settings default to true + in order to ease configuration. + + + + + Prefix= + + The IPv6 prefix that is to be distributed to hosts. Similarly to configuring static + IPv6 addresses, the setting is configured as an IPv6 prefix and its prefix length, separated by a + / character. Use multiple [IPv6Prefix] sections to configure multiple IPv6 + prefixes since prefix lifetimes, address autoconfiguration and onlink status may differ from one + prefix to another. + + + + PreferredLifetimeSec= + ValidLifetimeSec= + + Preferred and valid lifetimes for the prefix measured in seconds. + PreferredLifetimeSec= defaults to 1800 seconds (30 minutes) and + ValidLifetimeSec= defaults to 3600 seconds (one hour). + + + + Assign= + Takes a boolean. When true, adds an address from the prefix. Default to false. + + + + + Token= + + Specifies an optional address generation mode for assigning an address in each + prefix. This accepts the same syntax as Token= in the [IPv6AcceptRA] + section. If Assign= is set to false, then this setting will be ignored. + Defaults to unset, which means the EUI-64 algorithm will be used. + + + + + RouteMetric= + + The metric of the prefix route. Takes an unsigned integer in the range 0…4294967295. + When unset or set to 0, the kernel's default value is used. This setting is ignored when + Assign= is false. + + + + + + + [IPv6RoutePrefix] Section Options + One or more [IPv6RoutePrefix] sections contain the IPv6 + prefix routes that are announced via Router Advertisements. See + RFC 4191 + for further details. + + + + + Route= + + The IPv6 route that is to be distributed to hosts. Similarly to configuring static + IPv6 routes, the setting is configured as an IPv6 prefix routes and its prefix route length, + separated by a / character. Use multiple [IPv6RoutePrefix] sections to configure + multiple IPv6 prefix routes. + + + + LifetimeSec= + + Lifetime for the route prefix measured in seconds. + LifetimeSec= defaults to 3600 seconds (one hour). + + + + + + + [Bridge] Section Options + The [Bridge] section accepts the following keys: + + + UnicastFlood= + + Takes a boolean. Controls whether the bridge should flood + traffic for which an FDB entry is missing and the destination + is unknown through this port. When unset, the kernel's default will be used. + + + + + MulticastFlood= + + Takes a boolean. Controls whether the bridge should flood + traffic for which an MDB entry is missing and the destination + is unknown through this port. When unset, the kernel's default will be used. + + + + + MulticastToUnicast= + + Takes a boolean. Multicast to unicast works on top of the multicast snooping feature of + the bridge. Which means unicast copies are only delivered to hosts which are interested in it. + When unset, the kernel's default will be used. + + + + + NeighborSuppression= + + Takes a boolean. Configures whether ARP and ND neighbor suppression is enabled for + this port. When unset, the kernel's default will be used. + + + + + Learning= + + Takes a boolean. Configures whether MAC address learning is enabled for + this port. When unset, the kernel's default will be used. + + + + + HairPin= + + Takes a boolean. Configures whether traffic may be sent back out of the port on which it + was received. When this flag is false, then the bridge will not forward traffic back out of the + receiving port. When unset, the kernel's default will be used. + + + + Isolated= + + Takes a boolean. Configures whether this port is isolated or not. Within a bridge, + isolated ports can only communicate with non-isolated ports. When set to true, this port can only + communicate with other ports whose Isolated setting is false. When set to false, this port + can communicate with any other ports. When unset, the kernel's default will be used. + + + + UseBPDU= + + Takes a boolean. Configures whether STP Bridge Protocol Data Units will be + processed by the bridge port. When unset, the kernel's default will be used. + + + + FastLeave= + + Takes a boolean. This flag allows the bridge to immediately stop multicast + traffic on a port that receives an IGMP Leave message. It is only used with + IGMP snooping if enabled on the bridge. When unset, the kernel's default will be used. + + + + AllowPortToBeRoot= + + Takes a boolean. Configures whether a given port is allowed to + become a root port. Only used when STP is enabled on the bridge. + When unset, the kernel's default will be used. + + + + ProxyARP= + + Takes a boolean. Configures whether proxy ARP to be enabled on this port. + When unset, the kernel's default will be used. + + + + ProxyARPWiFi= + + Takes a boolean. Configures whether proxy ARP to be enabled on this port + which meets extended requirements by IEEE 802.11 and Hotspot 2.0 specifications. + When unset, the kernel's default will be used. + + + + MulticastRouter= + + Configures this port for having multicast routers attached. A port with a multicast + router will receive all multicast traffic. Takes one of no + to disable multicast routers on this port, query to let the system detect + the presence of routers, permanent to permanently enable multicast traffic + forwarding on this port, or temporary to enable multicast routers temporarily + on this port, not depending on incoming queries. When unset, the kernel's default will be used. + + + + Cost= + + Sets the "cost" of sending packets of this interface. + Each port in a bridge may have a different speed and the cost + is used to decide which link to use. Faster interfaces + should have lower costs. It is an integer value between 1 and + 65535. + + + + Priority= + + Sets the "priority" of sending packets on this interface. + Each port in a bridge may have a different priority which is used + to decide which link to use. Lower value means higher priority. + It is an integer value between 0 to 63. Networkd does not set any + default, meaning the kernel default value of 32 is used. + + + + + + [BridgeFDB] Section Options + The [BridgeFDB] section manages the forwarding database table of a port and accepts the following + keys. Specify several [BridgeFDB] sections to configure several static MAC table entries. + + + + MACAddress= + + As in the [Network] section. This key is mandatory. + + + + Destination= + + Takes an IP address of the destination VXLAN tunnel endpoint. + + + + VLANId= + + The VLAN ID for the new static MAC table entry. If + omitted, no VLAN ID information is appended to the new static MAC + table entry. + + + + VNI= + + The VXLAN Network Identifier (or VXLAN Segment ID) to use to connect to + the remote VXLAN tunnel endpoint. Takes a number in the range 1…16777215. + Defaults to unset. + + + + AssociatedWith= + + Specifies where the address is associated with. Takes one of use, + self, master or router. + use means the address is in use. User space can use this option to + indicate to the kernel that the fdb entry is in use. self means + the address is associated with the port drivers fdb. Usually hardware. master + means the address is associated with master devices fdb. router means + the destination address is associated with a router. Note that it's valid if the referenced + device is a VXLAN type device and has route shortcircuit enabled. Defaults to self. + + + + OutgoingInterface= + + Specifies the name or index of the outgoing interface for the VXLAN device driver to + reach the remote VXLAN tunnel endpoint. Defaults to unset. + + + + + + [BridgeMDB] Section Options + The [BridgeMDB] section manages the multicast membership entries forwarding database table of a port and accepts the following + keys. Specify several [BridgeMDB] sections to configure several permanent multicast membership entries. + + + + MulticastGroupAddress= + + Specifies the IPv4 or IPv6 multicast group address to add. This setting is mandatory. + + + + VLANId= + + The VLAN ID for the new entry. Valid ranges are 0 (no VLAN) to 4094. Optional, defaults to 0. + + + + + + + [LLDP] Section Options + The [LLDP] section manages the Link Layer Discovery Protocol (LLDP) and accepts the following + keys: + + + MUDURL= + + When configured, the specified Manufacturer Usage Descriptions (MUD) URL will be sent in + LLDP packets. The syntax and semantics are the same as for MUDURL= in the + [DHCPv4] section described above. + + The MUD URLs received via LLDP packets are saved and can be read using the + sd_lldp_neighbor_get_mud_url() function. + + + + + + + [CAN] Section Options + The [CAN] section manages the Controller Area Network (CAN bus) and accepts the + following keys: + + + BitRate= + + The bitrate of CAN device in bits per second. The usual SI prefixes (K, M) with the base of 1000 can + be used here. Takes a number in the range 1…4294967295. + + + + SamplePoint= + + Optional sample point in percent with one decimal (e.g. 75%, + 87.5%) or permille (e.g. 875‰). This will be ignored when + BitRate= is unspecified. + + + + TimeQuantaNSec= + PropagationSegment= + PhaseBufferSegment1= + PhaseBufferSegment2= + SyncJumpWidth= + + Specifies the time quanta, propagation segment, phase buffer segment 1 and 2, and the + synchronization jump width, which allow one to define the CAN bit-timing in a hardware + independent format as proposed by the Bosch CAN 2.0 Specification. + TimeQuantaNSec= takes a timespan in nanoseconds. + PropagationSegment=, PhaseBufferSegment1=, + PhaseBufferSegment2=, and SyncJumpWidth= take number + of time quantum specified in TimeQuantaNSec= and must be an unsigned + integer in the range 0…4294967295. These settings except for + SyncJumpWidth= will be ignored when BitRate= is + specified. + + + + DataBitRate= + DataSamplePoint= + + The bitrate and sample point for the data phase, if CAN-FD is used. These settings are + analogous to the BitRate= and SamplePoint= keys. + + + + DataTimeQuantaNSec= + DataPropagationSegment= + DataPhaseBufferSegment1= + DataPhaseBufferSegment2= + DataSyncJumpWidth= + + Specifies the time quanta, propagation segment, phase buffer segment 1 and 2, and the + synchronization jump width for the data phase, if CAN-FD is used. These settings are + analogous to the TimeQuantaNSec= or related settings. + + + + FDMode= + + Takes a boolean. When yes, CAN-FD mode is enabled for the interface. + Note, that a bitrate and optional sample point should also be set for the CAN-FD data phase using + the DataBitRate= and DataSamplePoint= keys, or + DataTimeQuanta= and related settings. + + + + FDNonISO= + + Takes a boolean. When yes, non-ISO CAN-FD mode is enabled for the + interface. When unset, the kernel's default will be used. + + + + RestartSec= + + Automatic restart delay time. If set to a non-zero value, a restart of the CAN controller will be + triggered automatically in case of a bus-off condition after the specified delay time. Subsecond delays can + be specified using decimals (e.g. 0.1s) or a ms or + us postfix. Using infinity or 0 will turn the + automatic restart off. By default automatic restart is disabled. + + + + Termination= + + Takes a boolean or a termination resistor value in ohm in the range 0…65535. When + yes, the termination resistor is set to 120 ohm. When + no or 0 is set, the termination resistor is disabled. + When unset, the kernel's default will be used. + + + + TripleSampling= + + Takes a boolean. When yes, three samples (instead of one) are used to determine + the value of a received bit by majority rule. When unset, the kernel's default will be used. + + + + BusErrorReporting= + + Takes a boolean. When yes, reporting of CAN bus errors is activated + (those include single bit, frame format, and bit stuffing errors, unable to send dominant bit, + unable to send recessive bit, bus overload, active error announcement, error occurred on + transmission). When unset, the kernel's default will be used. Note: in case of a CAN bus with a + single CAN device, sending a CAN frame may result in a huge number of CAN bus errors. + + + + ListenOnly= + + Takes a boolean. When yes, listen-only mode is enabled. When the + interface is in listen-only mode, the interface neither transmit CAN frames nor send ACK + bit. Listen-only mode is important to debug CAN networks without interfering with the + communication or acknowledge the CAN frame. When unset, the kernel's default will be used. + + + + + Loopback= + + Takes a boolean. When yes, loopback mode is enabled. When the + loopback mode is enabled, the interface treats messages transmitted by itself as received + messages. The loopback mode is important to debug CAN networks. When unset, the kernel's + default will be used. + + + + OneShot= + + Takes a boolean. When yes, one-shot mode is enabled. When unset, + the kernel's default will be used. + + + + PresumeAck= + + Takes a boolean. When yes, the interface will ignore missing CAN + ACKs. When unset, the kernel's default will be used. + + + + ClassicDataLengthCode= + + Takes a boolean. When yes, the interface will handle the 4bit data + length code (DLC). When unset, the kernel's default will be used. + + + + + + + [IPoIB] Section Options + The [IPoIB] section manages the IP over Infiniband and accepts the following keys: + + + + + + + + [QDisc] Section Options + The [QDisc] section manages the traffic control queueing discipline (qdisc). + + + + Parent= + + Specifies the parent Queueing Discipline (qdisc). Takes one of clsact + or ingress. This is mandatory. + + + + + + + + + [NetworkEmulator] Section Options + The [NetworkEmulator] section manages the queueing discipline (qdisc) of the network emulator. It + can be used to configure the kernel packet scheduler and simulate packet delay and loss for UDP or TCP + applications, or limit the bandwidth usage of a particular service to simulate internet connections. + + + + + + + + DelaySec= + + Specifies the fixed amount of delay to be added to all packets going out of the + interface. Defaults to unset. + + + + + DelayJitterSec= + + Specifies the chosen delay to be added to the packets outgoing to the network + interface. Defaults to unset. + + + + + PacketLimit= + + Specifies the maximum number of packets the qdisc may hold queued at a time. + An unsigned integer in the range 0…4294967294. Defaults to 1000. + + + + + LossRate= + + Specifies an independent loss probability to be added to the packets outgoing from the + network interface. Takes a percentage value, suffixed with "%". Defaults to unset. + + + + + DuplicateRate= + + Specifies that the chosen percent of packets is duplicated before queuing them. + Takes a percentage value, suffixed with "%". Defaults to unset. + + + + + + + [TokenBucketFilter] Section Options + The [TokenBucketFilter] section manages the queueing discipline (qdisc) of token bucket filter + (tbf). + + + + + + + LatencySec= + + Specifies the latency parameter, which specifies the maximum amount of time a + packet can sit in the Token Bucket Filter (TBF). Defaults to unset. + + + + + LimitBytes= + + Takes the number of bytes that can be queued waiting for tokens to become available. + When the size is suffixed with K, M, or G, it is parsed as Kilobytes, Megabytes, or Gigabytes, + respectively, to the base of 1024. Defaults to unset. + + + + + BurstBytes= + + Specifies the size of the bucket. This is the maximum amount of bytes that tokens + can be available for instantaneous transfer. When the size is suffixed with K, M, or G, it is + parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to + unset. + + + + + Rate= + + Specifies the device specific bandwidth. When suffixed with K, M, or G, the specified + bandwidth is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000. + Defaults to unset. + + + + + MPUBytes= + + The Minimum Packet Unit (MPU) determines the minimal token usage (specified in bytes) + for a packet. When suffixed with K, M, or G, the specified size is parsed as Kilobytes, + Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to zero. + + + + + PeakRate= + + Takes the maximum depletion rate of the bucket. When suffixed with K, M, or G, the + specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of + 1000. Defaults to unset. + + + + + MTUBytes= + + Specifies the size of the peakrate bucket. When suffixed with K, M, or G, the specified + size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. + Defaults to unset. + + + + + + + [PIE] Section Options + The [PIE] section manages the queueing discipline (qdisc) of Proportional Integral + controller-Enhanced (PIE). + + + + + + + PacketLimit= + + Specifies the hard limit on the queue size in number of packets. When this limit is reached, + incoming packets are dropped. An unsigned integer in the range 1…4294967294. Defaults to unset and + kernel's default is used. + + + + + + + [FlowQueuePIE] Section Options + The [FlowQueuePIE] section manages the queueing discipline + (qdisc) of Flow Queue Proportional Integral controller-Enhanced (fq_pie). + + + + + + + PacketLimit= + + Specifies the hard limit on the queue size in number of packets. When this limit is reached, + incoming packets are dropped. An unsigned integer ranges 1 to 4294967294. Defaults to unset and + kernel's default is used. + + + + + + + [StochasticFairBlue] Section Options + The [StochasticFairBlue] section manages the queueing discipline (qdisc) of stochastic fair blue + (sfb). + + + + + + + PacketLimit= + + Specifies the hard limit on the queue size in number of packets. When this limit is reached, + incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and + kernel's default is used. + + + + + + + [StochasticFairnessQueueing] Section Options + The [StochasticFairnessQueueing] section manages the queueing discipline (qdisc) of stochastic + fairness queueing (sfq). + + + + + + + PerturbPeriodSec= + + Specifies the interval in seconds for queue algorithm perturbation. Defaults to unset. + + + + + + + [BFIFO] Section Options + The [BFIFO] section manages the queueing discipline (qdisc) of Byte limited Packet First In First + Out (bfifo). + + + + + + + LimitBytes= + + Specifies the hard limit in bytes on the FIFO buffer size. The size limit prevents overflow + in case the kernel is unable to dequeue packets as quickly as it receives them. When this limit is + reached, incoming packets are dropped. When suffixed with K, M, or G, the specified size is parsed + as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and + kernel default is used. + + + + + + + [PFIFO] Section Options + The [PFIFO] section manages the queueing discipline (qdisc) of Packet First In First Out + (pfifo). + + + + + + + PacketLimit= + + Specifies the hard limit on the number of packets in the FIFO queue. The size limit prevents + overflow in case the kernel is unable to dequeue packets as quickly as it receives them. When this + limit is reached, incoming packets are dropped. An unsigned integer in the range + 0…4294967294. Defaults to unset and kernel's default is used. + + + + + + + [PFIFOHeadDrop] Section Options + The [PFIFOHeadDrop] section manages the queueing discipline (qdisc) of Packet First In First Out + Head Drop (pfifo_head_drop). + + + + + + + PacketLimit= + + As in [PFIFO] section. + + + + + + [PFIFOFast] Section Options + The [PFIFOFast] section manages the queueing discipline (qdisc) of Packet First In First Out Fast + (pfifo_fast). + + + + + + + + + [CAKE] Section Options + The [CAKE] section manages the queueing discipline (qdisc) of Common Applications Kept Enhanced + (CAKE). + + + + + + + Bandwidth= + + Specifies the shaper bandwidth. When suffixed with K, M, or G, the specified size is + parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of 1000. Defaults to + unset and kernel's default is used. + + + + + AutoRateIngress= + + Takes a boolean value. Enables automatic capacity estimation based on traffic arriving + at this qdisc. This is most likely to be useful with cellular links, which tend to change + quality randomly. If this setting is enabled, the Bandwidth= setting is + used as an initial estimate. Defaults to unset, and the kernel's default is used. + + + + + OverheadBytes= + + Specifies that bytes to be addeded to the size of each packet. Bytes may be negative. + Takes an integer in the range -64…256. Defaults to unset and kernel's default is used. + + + + + + MPUBytes= + + Rounds each packet (including overhead) up to the specified bytes. Takes an integer in + the range 1…256. Defaults to unset and kernel's default is used. + + + + + CompensationMode= + + Takes one of none, atm, or ptm. + Specifies the compensation mode for overhead calculation. When none, no + compensation is taken into account. When atm, enables the compensation for + ATM cell framing, which is normally found on ADSL links. When ptm, enables + the compensation for PTM encoding, which is normally found on VDSL2 links and uses a 64b/65b + encoding scheme. Defaults to unset and the kernel's default is used. + + + + + UseRawPacketSize= + + Takes a boolean value. When true, the packet size reported by the Linux kernel will be + used, instead of the underlying IP packet size. Defaults to unset, and the kernel's default + is used. + + + + + FlowIsolationMode= + + CAKE places packets from different flows into different queues, then packets from each + queue are delivered fairly. This specifies whether the fairness is based on source address, + destination address, individual flows, or any combination of those. The available values are: + + + + + + + The flow isolation is disabled, and all traffic passes through a single queue. + + + + + + Flows are defined only by source address. Equivalent to the srchost + option for tc qdisc command. See also + tc-cake8. + + + + + + Flows are defined only by destination address. Equivalent to the + dsthost option for tc qdisc command. See also + tc-cake8. + + + + + + Flows are defined by source-destination host pairs. Equivalent to the same option for + tc qdisc command. See also + tc-cake8. + + + + + + Flows are defined by the entire 5-tuple of source address, destination address, + transport protocol, source port and destination port. Equivalent to the same option for + tc qdisc command. See also + tc-cake8. + + + + + + Flows are defined by the 5-tuple (see flows in the above), and + fairness is applied first over source addresses, then over individual flows. Equivalent + to the dual-srchost option for tc qdisc command. + See also + tc-cake8. + + + + + + Flows are defined by the 5-tuple (see flows in the above), and + fairness is applied first over destination addresses, then over individual flows. + Equivalent to the dual-dsthost option for + tc qdisc command. See also + tc-cake8. + + + + + + Flows are defined by the 5-tuple (see flows), and fairness is + applied over source and destination addresses, and also over individual flows. + Equivalent to the triple-isolate option for + tc qdisc command. See also + tc-cake8. + + + + + Defaults to unset and the kernel's default is used. + + + + + NAT= + + Takes a boolean value. When true, CAKE performs a NAT lookup before applying + flow-isolation rules, to determine the true addresses and port numbers of the packet, to + improve fairness between hosts inside the NAT. This has no practical effect when + FlowIsolationMode= is none or flows, + or if NAT is performed on a different host. Defaults to unset, and the kernel's default is + used. + + + + + PriorityQueueingPreset= + + CAKE divides traffic into tins, and each tin has its own independent + set of flow-isolation queues, bandwidth threshold, and priority. This specifies the preset of + tin profiles. The available values are: + + + + + + Disables priority queueing by placing all traffic in one tin. + + + + + + Enables priority queueing based on the legacy interpretation of TOS + Precedence field. Use of this preset on the modern Internet is + firmly discouraged. + + + + + + Enables priority queueing based on the Differentiated Service + (DiffServ) field with eight tins: Background Traffic, High + Throughput, Best Effort, Video Streaming, Low Latency Transactions, Interactive Shell, + Minimum Latency, and Network Control. + + + + + + Enables priority queueing based on the Differentiated Service + (DiffServ) field with four tins: Background Traffic, Best Effort, + Streaming Media, and Latency Sensitive. + + + + + + Enables priority queueing based on the Differentiated Service + (DiffServ) field with three tins: Background Traffic, Best Effort, + and Latency Sensitive. + + + + + Defaults to unset, and the kernel's default is used. + + + + + FirewallMark= + + Takes an integer in the range 1…4294967295. When specified, firewall-mark-based + overriding of CAKE's tin selection is enabled. Defaults to unset, and the kernel's default is + used. + + + + + Wash= + + Takes a boolean value. When true, CAKE clears the DSCP fields, except for ECN bits, of + any packet passing through CAKE. Defaults to unset, and the kernel's default is used. + + + + + SplitGSO= + + Takes a boolean value. When true, CAKE will split General Segmentation Offload (GSO) + super-packets into their on-the-wire components and dequeue them individually. Defaults to + unset, and the kernel's default is used. + + + + + + + + [ControlledDelay] Section Options + The [ControlledDelay] section manages the queueing discipline (qdisc) of + controlled delay (CoDel). + + + + + + + PacketLimit= + + Specifies the hard limit on the queue size in number of packets. When this limit is reached, + incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and + kernel's default is used. + + + + + TargetSec= + + Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay. + Defaults to unset and kernel's default is used. + + + + + IntervalSec= + + Takes a timespan. This is used to ensure that the measured minimum delay does not + become too stale. Defaults to unset and kernel's default is used. + + + + + ECN= + + Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to + unset and kernel's default is used. + + + + + CEThresholdSec= + + Takes a timespan. This sets a threshold above which all packets are marked with ECN + Congestion Experienced (CE). Defaults to unset and kernel's default is used. + + + + + + + [DeficitRoundRobinScheduler] Section Options + The [DeficitRoundRobinScheduler] section manages the queueing discipline (qdisc) of Deficit Round + Robin Scheduler (DRR). + + + + + + + + + [DeficitRoundRobinSchedulerClass] Section Options + The [DeficitRoundRobinSchedulerClass] section manages the traffic control class of Deficit Round + Robin Scheduler (DRR). + + + + + + + QuantumBytes= + + Specifies the amount of bytes a flow is allowed to dequeue before the scheduler moves + to the next class. When suffixed with K, M, or G, the specified size is parsed as Kilobytes, + Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to the MTU of the + interface. + + + + + + + + [EnhancedTransmissionSelection] Section Options + The [EnhancedTransmissionSelection] section manages the queueing discipline (qdisc) of Enhanced + Transmission Selection (ETS). + + + + + + + Bands= + + Specifies the number of bands. An unsigned integer in the range 1…16. This value has to be at + least large enough to cover the strict bands specified through the StrictBands= + and bandwidth-sharing bands specified in QuantumBytes=. + + + + + StrictBands= + + Specifies the number of bands that should be created in strict mode. An unsigned integer in + the range 1…16. + + + + + QuantumBytes= + + Specifies the white-space separated list of quantum used in band-sharing bands. When + suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, + respectively, to the base of 1024. This setting can be specified multiple times. If an empty + string is assigned, then the all previous assignments are cleared. + + + + + PriorityMap= + + The priority map maps the priority of a packet to a band. The argument is a whitespace + separated list of numbers. The first number indicates which band the packets with priority 0 should + be put to, the second is for priority 1, and so on. There can be up to 16 numbers in the list. If + there are fewer, the default band that traffic with one of the unmentioned priorities goes to is + the last one. Each band number must be in the range 0…255. This setting can be specified multiple + times. If an empty string is assigned, then the all previous assignments are cleared. + + + + + + + [GenericRandomEarlyDetection] Section Options + The [GenericRandomEarlyDetection] section manages the queueing discipline (qdisc) of Generic Random + Early Detection (GRED). + + + + + + + VirtualQueues= + + Specifies the number of virtual queues. Takes an integer in the range 1…16. Defaults to unset + and kernel's default is used. + + + + + DefaultVirtualQueue= + + Specifies the number of default virtual queue. This must be less than VirtualQueue=. + Defaults to unset and kernel's default is used. + + + + + GenericRIO= + + Takes a boolean. It turns on the RIO-like buffering scheme. Defaults to + unset and kernel's default is used. + + + + + + + [FairQueueingControlledDelay] Section Options + The [FairQueueingControlledDelay] section manages the queueing discipline (qdisc) of fair queuing + controlled delay (FQ-CoDel). + + + + + + + PacketLimit= + + Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are + dropped. Defaults to unset and kernel's default is used. + + + + + MemoryLimitBytes= + + Specifies the limit on the total number of bytes that can be queued in this FQ-CoDel instance. + When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, + respectively, to the base of 1024. Defaults to unset and kernel's default is used. + + + + + Flows= + + Specifies the number of flows into which the incoming packets are classified. + Defaults to unset and kernel's default is used. + + + + + TargetSec= + + Takes a timespan. Specifies the acceptable minimum standing/persistent queue delay. + Defaults to unset and kernel's default is used. + + + + + IntervalSec= + + Takes a timespan. This is used to ensure that the measured minimum delay does not + become too stale. Defaults to unset and kernel's default is used. + + + + + QuantumBytes= + + Specifies the number of bytes used as the "deficit" in the fair queuing algorithm timespan. + When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, + respectively, to the base of 1024. Defaults to unset and kernel's default is used. + + + + + ECN= + + Takes a boolean. This can be used to mark packets instead of dropping them. Defaults to + unset and kernel's default is used. + + + + + CEThresholdSec= + + Takes a timespan. This sets a threshold above which all packets are marked with ECN + Congestion Experienced (CE). Defaults to unset and kernel's default is used. + + + + + + + [FairQueueing] Section Options + The [FairQueueing] section manages the queueing discipline (qdisc) of fair queue traffic policing + (FQ). + + + + + + + PacketLimit= + + Specifies the hard limit on the real queue size. When this limit is reached, incoming packets are + dropped. Defaults to unset and kernel's default is used. + + + + + FlowLimit= + + Specifies the hard limit on the maximum number of packets queued per flow. Defaults to + unset and kernel's default is used. + + + + + QuantumBytes= + + Specifies the credit per dequeue RR round, i.e. the amount of bytes a flow is allowed + to dequeue at once. When suffixed with K, M, or G, the specified size is parsed as Kilobytes, + Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and kernel's + default is used. + + + + + InitialQuantumBytes= + + Specifies the initial sending rate credit, i.e. the amount of bytes a new flow is + allowed to dequeue initially. When suffixed with K, M, or G, the specified size is parsed as + Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. Defaults to unset and + kernel's default is used. + + + + + MaximumRate= + + Specifies the maximum sending rate of a flow. When suffixed with K, M, or G, the + specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, to the base of + 1000. Defaults to unset and kernel's default is used. + + + + + Buckets= + + Specifies the size of the hash table used for flow lookups. Defaults to unset and + kernel's default is used. + + + + + OrphanMask= + + Takes an unsigned integer. For packets not owned by a socket, fq is able to mask a part + of hash and reduce number of buckets associated with the traffic. Defaults to unset and + kernel's default is used. + + + + + Pacing= + + Takes a boolean, and enables or disables flow pacing. Defaults to unset and kernel's + default is used. + + + + + CEThresholdSec= + + Takes a timespan. This sets a threshold above which all packets are marked with ECN + Congestion Experienced (CE). Defaults to unset and kernel's default is used. + + + + + + + [TrivialLinkEqualizer] Section Options + The [TrivialLinkEqualizer] section manages the queueing discipline (qdisc) of trivial link + equalizer (teql). + + + + + + + Id= + + Specifies the interface ID N of teql. Defaults to 0. + Note that when teql is used, currently, the module sch_teql with + max_equalizers=N+1 option must be loaded before + systemd-networkd is started. + + + + + + + [HierarchyTokenBucket] Section Options + The [HierarchyTokenBucket] section manages the queueing discipline (qdisc) of hierarchy token + bucket (htb). + + + + + + + DefaultClass= + + Takes the minor id in hexadecimal of the default class. Unclassified traffic gets sent + to the class. Defaults to unset. + + + + + RateToQuantum= + + Takes an unsigned integer. The DRR quantums are calculated by dividing the value + configured in Rate= by RateToQuantum=. + + + + + + + [HierarchyTokenBucketClass] Section Options + The [HierarchyTokenBucketClass] section manages the traffic control class of hierarchy token bucket + (htb). + + + + + + + Priority= + + Specifies the priority of the class. In the round-robin process, classes with the lowest + priority field are tried for packets first. + + + + + QuantumBytes= + + Specifies how many bytes to serve from leaf at once. When suffixed with K, M, or G, the + specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of + 1024. + + + + + MTUBytes= + + Specifies the maximum packet size we create. When suffixed with K, M, or G, the specified + size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of 1024. + + + + + OverheadBytes= + + Takes an unsigned integer which specifies per-packet size overhead used in rate + computations. When suffixed with K, M, or G, the specified size is parsed as Kilobytes, + Megabytes, or Gigabytes, respectively, to the base of 1024. + + + + + Rate= + + Specifies the maximum rate this class and all its children are guaranteed. When suffixed + with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, respectively, + to the base of 1000. This setting is mandatory. + + + + + CeilRate= + + Specifies the maximum rate at which a class can send, if its parent has bandwidth to spare. + When suffixed with K, M, or G, the specified size is parsed as Kilobits, Megabits, or Gigabits, + respectively, to the base of 1000. When unset, the value specified with Rate= + is used. + + + + + BufferBytes= + + Specifies the maximum bytes burst which can be accumulated during idle period. When suffixed + with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, + to the base of 1024. + + + + + CeilBufferBytes= + + Specifies the maximum bytes burst for ceil which can be accumulated during idle period. + When suffixed with K, M, or G, the specified size is parsed as Kilobytes, Megabytes, or Gigabytes, + respectively, to the base of 1024. + + + + + + + [HeavyHitterFilter] Section Options + The [HeavyHitterFilter] section manages the queueing discipline (qdisc) of Heavy Hitter Filter + (hhf). + + + + + + + PacketLimit= + + Specifies the hard limit on the queue size in number of packets. When this limit is reached, + incoming packets are dropped. An unsigned integer in the range 0…4294967294. Defaults to unset and + kernel's default is used. + + + + + + + [QuickFairQueueing] Section Options + The [QuickFairQueueing] section manages the queueing discipline (qdisc) of Quick Fair Queueing + (QFQ). + + + + + + + + + [QuickFairQueueingClass] Section Options + The [QuickFairQueueingClass] section manages the traffic control class of Quick Fair Queueing + (qfq). + + + + + + + Weight= + + Specifies the weight of the class. Takes an integer in the range 1…1023. Defaults to + unset in which case the kernel default is used. + + + + + MaxPacketBytes= + + Specifies the maximum packet size in bytes for the class. When suffixed with K, M, or G, the + specified size is parsed as Kilobytes, Megabytes, or Gigabytes, respectively, to the base of + 1024. When unset, the kernel default is used. + + + + + + + [BridgeVLAN] Section Options + The [BridgeVLAN] section manages the VLAN ID configuration of a bridge port and accepts the + following keys. Specify several [BridgeVLAN] sections to configure several VLAN entries. The + VLANFiltering= option has to be enabled, see the [Bridge] section in + systemd.netdev5. + + + + VLAN= + + The VLAN ID allowed on the port. This can be either a single ID or a range M-N. Takes + an integer in the range 1…4094. + + + + EgressUntagged= + + The VLAN ID specified here will be used to untag frames on egress. Configuring + EgressUntagged= implicates the use of VLAN= above and will enable the + VLAN ID for ingress as well. This can be either a single ID or a range M-N. + + + + PVID= + + The Port VLAN ID specified here is assigned to all untagged frames at ingress. + PVID= can be used only once. Configuring PVID= implicates the use of + VLAN= above and will enable the VLAN ID for ingress as well. + + + + + + + Examples + + Static network configuration + + # /etc/systemd/network/50-static.network +[Match] +Name=enp2s0 + +[Network] +Address=192.168.0.15/24 +Gateway=192.168.0.1 + + This brings interface enp2s0 up with a static address. The + specified gateway will be used for a default route. + + + + DHCP on ethernet links + + # /etc/systemd/network/80-dhcp.network +[Match] +Name=en* + +[Network] +DHCP=yes + + This will enable DHCPv4 and DHCPv6 on all interfaces with names starting with + en (i.e. ethernet interfaces). + + + + IPv6 Prefix Delegation (DHCPv6 PD) + + # /etc/systemd/network/55-dhcpv6-pd-upstream.network +[Match] +Name=enp1s0 + +[Network] +DHCP=ipv6 + +# The below setting is optional, to also assign an address in the delegated prefix +# to the upstream interface. If not necessary, then comment out the line below and +# the [DHCPPrefixDelegation] section. +DHCPPrefixDelegation=yes + +# If the upstream network provides Router Advertisement with Managed bit set, +# then comment out the line below and WithoutRA= setting in the [DHCPv6] section. +IPv6AcceptRA=no + +[DHCPv6] +WithoutRA=solicit + +[DHCPPrefixDelegation] +UplinkInterface=:self +SubnetId=0 +Announce=no + + # /etc/systemd/network/55-dhcpv6-pd-downstream.network +[Match] +Name=enp2s0 + +[Network] +DHCPPrefixDelegation=yes +IPv6SendRA=yes + +# It is expected that the host is acting as a router. So, usually it is not +# necessary to receive Router Advertisement from other hosts in the downstream network. +IPv6AcceptRA=no + +[DHCPPrefixDelegation] +UplinkInterface=enp1s0 +SubnetId=1 +Announce=yes + + This will enable DHCPv6-PD on the interface enp1s0 as an upstream interface where the + DHCPv6 client is running and enp2s0 as a downstream interface where the prefix is delegated to. + The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network. + + + + + IPv6 Prefix Delegation (DHCPv4 6RD) + + # /etc/systemd/network/55-dhcpv4-6rd-upstream.network +[Match] +Name=enp1s0 + +[Network] +DHCP=ipv4 + +# When DHCPv4-6RD is used, the upstream network does not support IPv6. +# Hence, it is not necessary to wait for Router Advertisement, which is enabled by default. +IPv6AcceptRA=no + +[DHCPv4] +Use6RD=yes + + # /etc/systemd/network/55-dhcpv4-6rd-downstream.network +[Match] +Name=enp2s0 + +[Network] +DHCPPrefixDelegation=yes +IPv6SendRA=yes + +# It is expected that the host is acting as a router. So, usually it is not +# necessary to receive Router Advertisement from other hosts in the downstream network. +IPv6AcceptRA=no + +[DHCPPrefixDelegation] +UplinkInterface=enp1s0 +SubnetId=1 +Announce=yes + + This will enable DHCPv4-6RD on the interface enp1s0 as an upstream interface where the + DHCPv4 client is running and enp2s0 as a downstream interface where the prefix is delegated to. + The delegated prefixes are distributed by IPv6 Router Advertisement on the downstream network. + + + + + A bridge with two enslaved links + + # /etc/systemd/network/25-bridge-static.netdev +[NetDev] +Name=bridge0 +Kind=bridge + + # /etc/systemd/network/25-bridge-static.network +[Match] +Name=bridge0 + +[Network] +Address=192.168.0.15/24 +Gateway=192.168.0.1 +DNS=192.168.0.1 + + # /etc/systemd/network/25-bridge-slave-interface-1.network +[Match] +Name=enp2s0 + +[Network] +Bridge=bridge0 + + # /etc/systemd/network/25-bridge-slave-interface-2.network +[Match] +Name=wlp3s0 + +[Network] +Bridge=bridge0 + + This creates a bridge and attaches devices enp2s0 and + wlp3s0 to it. The bridge will have the specified static address + and network assigned, and a default route via the specified gateway will be + added. The specified DNS server will be added to the global list of DNS resolvers. + + + + + Bridge port with VLAN forwarding + + +# /etc/systemd/network/25-bridge-slave-interface-1.network +[Match] +Name=enp2s0 + +[Network] +Bridge=bridge0 + +[BridgeVLAN] +VLAN=1-32 +PVID=42 +EgressUntagged=42 + +[BridgeVLAN] +VLAN=100-200 + +[BridgeVLAN] +EgressUntagged=300-400 + + This overrides the configuration specified in the previous example for the + interface enp2s0, and enables VLAN on that bridge port. VLAN IDs + 1-32, 42, 100-400 will be allowed. Packets tagged with VLAN IDs 42, 300-400 will be + untagged when they leave on this interface. Untagged packets which arrive on this + interface will be assigned VLAN ID 42. + + + + Various tunnels + + /etc/systemd/network/25-tunnels.network +[Match] +Name=ens1 + +[Network] +Tunnel=ipip-tun +Tunnel=sit-tun +Tunnel=gre-tun +Tunnel=vti-tun + + + /etc/systemd/network/25-tunnel-ipip.netdev +[NetDev] +Name=ipip-tun +Kind=ipip + + + /etc/systemd/network/25-tunnel-sit.netdev +[NetDev] +Name=sit-tun +Kind=sit + + + /etc/systemd/network/25-tunnel-gre.netdev +[NetDev] +Name=gre-tun +Kind=gre + + + /etc/systemd/network/25-tunnel-vti.netdev +[NetDev] +Name=vti-tun +Kind=vti + + + This will bring interface ens1 up and create an IPIP tunnel, + a SIT tunnel, a GRE tunnel, and a VTI tunnel using it. + + + + A bond device + + # /etc/systemd/network/30-bond1.network +[Match] +Name=bond1 + +[Network] +DHCP=ipv6 + + + # /etc/systemd/network/30-bond1.netdev +[NetDev] +Name=bond1 +Kind=bond + + + # /etc/systemd/network/30-bond1-dev1.network +[Match] +MACAddress=52:54:00:e9:64:41 + +[Network] +Bond=bond1 + + + # /etc/systemd/network/30-bond1-dev2.network +[Match] +MACAddress=52:54:00:e9:64:42 + +[Network] +Bond=bond1 + + + This will create a bond device bond1 and enslave the two + devices with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it. IPv6 DHCP + will be used to acquire an address. + + + + Virtual Routing and Forwarding (VRF) + Add the bond1 interface to the VRF master interface + vrf1. This will redirect routes generated on this interface to be + within the routing table defined during VRF creation. For kernels before 4.8 traffic + won't be redirected towards the VRFs routing table unless specific ip-rules are added. + + # /etc/systemd/network/25-vrf.network +[Match] +Name=bond1 + +[Network] +VRF=vrf1 + + + + + MacVTap + This brings up a network interface macvtap-test + and attaches it to enp0s25. + # /usr/lib/systemd/network/25-macvtap.network +[Match] +Name=enp0s25 + +[Network] +MACVTAP=macvtap-test + + + + + A Xfrm interface with physical underlying device. + + # /etc/systemd/network/27-xfrm.netdev +[NetDev] +Name=xfrm0 +Kind=xfrm + +[Xfrm] +InterfaceId=7 + + # /etc/systemd/network/27-eth0.network +[Match] +Name=eth0 + +[Network] +Xfrm=xfrm0 + + This creates a xfrm0 interface and binds it to the eth0 device. + This allows hardware based ipsec offloading to the eth0 nic. + If offloading is not needed, xfrm interfaces can be assigned to the lo device. + + + + + + See Also + + systemd1, + systemd-networkd.service8, + systemd.link5, + systemd.netdev5, + systemd-network-generator.service8, + systemd-resolved.service8 + + + + -- cgit v1.2.3