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// This is an example configuration file for the DHCPv4 server in Kea.
// It contains one subnet in which there are two static address reservations
// for the clients identified by the MAC addresses.
{ "Dhcp4":
{
// Kea is told to listen on eth0 interface only.
"interfaces-config": {
"interfaces": [ "eth0" ]
},
// We need to specify the database used to store leases. As of April
// 2022, three database backends are supported: MySQL, PostgreSQL, and the
// in-memory database, Memfile. We'll use memfile because it doesn't
// require any prior set up.
"lease-database": {
"type": "memfile",
"lfc-interval": 3600
},
// Addresses will be assigned with a lifetime of 4000 seconds.
"valid-lifetime": 4000,
// Renew and rebind timers are commented out. This implies that options
// 58 and 59 will not be sent to the client. In this case it is up to
// the client to pick the timer values according to RFC2131. Uncomment the
// timers to send these options to the client.
// "renew-timer": 1000,
// "rebind-timer": 2000,
// Kea supports reservations by several different types of identifiers:
// hw-address (hardware/MAC address of the client), duid (DUID inserted by the
// client), client-id (client identifier inserted by the client), circuit-id
// (circuit identifier inserted by the relay agent) and flex-id (flexible
// identifier available when flex_id hook library is loaded). When told to do
// so, Kea can check for all of those identifier types, but it takes a costly
// database lookup to do so. It is therefore useful from a performance
// perspective to use only the reservation types that are actually used in a
// given network.
// The example below is not optimal from a performance perspective, but it
// nicely showcases the host reservation capabilities. Please use the minimum
// set of identifier types used in your network.
"host-reservation-identifiers": [ "circuit-id", "hw-address", "duid",
"client-id", "flex-id" ],
// Define a subnet with four reservations. Some of the reservations belong
// to the dynamic pool. Kea is able to handle this case, but it is not
// recommended from a performance perspective, as Kea would not only need to
// check if a given address is free, but also whether it is reserved.
// To avoid this check, one can change reservation-mode to out-of-pool, rather
// than 'all'. If a subnet does not have reservations at all, the reservation
// lookup can be skipped altogether (reservation-mode is set to 'disabled').
// The reservation-mode has been replaced by reservations-global,
// reservations-in-subnet and reservations-out-of-pool.
// Note that the second reservation is for an address which is within the
// range of the pool of the dynamically allocated address. The server will
// exclude this address from this pool and only assign it to the client which
// has a reservation for it.
"subnet4": [
{
"pools": [ { "pool": "192.0.2.1 - 192.0.2.200" } ],
"subnet": "192.0.2.0/24",
"interface": "eth0",
// This directive tells Kea that reservations may be made both in-pool
// and out-of-pool. For improved performance, you may move all reservations
// out of the dynamic pool and change reservation-mode to "out-of-pool".
// Kea will then be able to skip querying for host reservations when
// assigning leases from dynamic pool.
// "reservation-mode": "all",
// It is replaced by the "reservations-global", "reservations-in-subnet"
// and "reservations-out-of-pool" parameters.
// Specify if server should lookup global reservations.
"reservations-global": false,
// Specify if server should lookup in-subnet reservations.
"reservations-in-subnet": true,
// Specify if server can assume that all reserved addresses
// are out-of-pool.
// Ignored when reservations-in-subnet is false.
// If specified, it is inherited by "shared-networks" and
// "subnet4" levels.
"reservations-out-of-pool": false,
"reservations": [
// This is a reservation for a specific hardware/MAC address. It's a very
// simple reservation: just an address and nothing else.
{
"hw-address": "1a:1b:1c:1d:1e:1f",
"ip-address": "192.0.2.201"
},
// This is a reservation for a specific client-id. It also shows
// the this client will get a reserved hostname. A hostname can be defined
// for any identifier type, not just client-id.
{
"client-id": "01:11:22:33:44:55:66",
"ip-address": "192.0.2.202",
"hostname": "special-snowflake"
},
// The third reservation is based on DUID. This reservation also
// defines special option values for this particular client. If
// the domain-name-servers option would have been defined on a global,
// subnet or class level, the host specific values take preference.
{
"duid": "01:02:03:04:05",
"ip-address": "192.0.2.203",
"option-data": [ {
"name": "domain-name-servers",
"data": "10.1.1.202,10.1.1.203"
} ]
},
// The fourth reservation is based on circuit-id. This is an option inserted
// by the relay agent that forwards the packet from client to the server.
// In this example the host is also assigned vendor specific options.
{
"circuit-id": "01:11:22:33:44:55:66",
"ip-address": "192.0.2.204",
"option-data": [
{
"name": "vivso-suboptions",
"data": "4491"
},
{
"name": "tftp-servers",
"space": "vendor-4491",
"data": "10.1.1.202,10.1.1.203"
}
]
},
// This reservation is for a client that needs specific DHCPv4 fields to be
// set. Three supported fields are next-server, server-hostname and
// boot-file-name
{
"client-id": "01:0a:0b:0c:0d:0e:0f",
"ip-address": "192.0.2.205",
"next-server": "192.0.2.1",
"server-hostname": "hal9000",
"boot-file-name": "/dev/null"
},
// This reservation is using flexible identifier. Instead of relying
// on specific field, sysadmin can define an expression similar to what
// is used for client classification,
// e.g. substring(relay[0].option[17],0,6). Then, based on the value of
// that expression for incoming packet, the reservation is matched.
// Expression can be specified either as hex or plain text using single
// quotes.
// Note: flexible identifier requires flex_id hook library to be
// loaded to work.
{
"flex-id": "'s0mEVaLue'",
"ip-address": "192.0.2.206"
}
]
}
],
// The following configures logging. It assumes that messages with at
// least informational level (info, warn, error and fatal) should be
// logged to stdout.
"loggers": [
{
"name": "kea-dhcp4",
"output_options": [
{
"output": "stdout"
}
],
"severity": "INFO"
}
]
}
}
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