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-rw-r--r--man7/ip.783
1 files changed, 50 insertions, 33 deletions
diff --git a/man7/ip.7 b/man7/ip.7
index d96afc7..34e2ff8 100644
--- a/man7/ip.7
+++ b/man7/ip.7
@@ -35,7 +35,7 @@
.\" commit 76e21053b5bf33a07c76f99d27a74238310e3c71
.\" Author: Erich E. Hoover <ehoover@mines.edu>
.\"
-.TH ip 7 2023-07-15 "Linux man-pages 6.05.01"
+.TH ip 7 2024-03-17 "Linux man-pages 6.7"
.SH NAME
ip \- Linux IPv4 protocol implementation
.SH SYNOPSIS
@@ -45,7 +45,7 @@ ip \- Linux IPv4 protocol implementation
.\" .B #include <linux/errqueue.h> -- never include <linux/foo.h>
.B #include <netinet/in.h>
.B #include <netinet/ip.h> \fR/* superset of previous */
-.PP
+.P
.IB tcp_socket " = socket(AF_INET, SOCK_STREAM, 0);"
.IB udp_socket " = socket(AF_INET, SOCK_DGRAM, 0);"
.IB raw_socket " = socket(AF_INET, SOCK_RAW, " protocol ");"
@@ -56,20 +56,20 @@ described in RFC\ 791 and RFC\ 1122.
.B ip
contains a level 2 multicasting implementation conforming to RFC\ 1112.
It also contains an IP router including a packet filter.
-.PP
+.P
The programming interface is BSD-sockets compatible.
For more information on sockets, see
.BR socket (7).
-.PP
+.P
An IP socket is created using
.BR socket (2):
-.PP
+.P
.in +4n
.EX
socket(AF_INET, socket_type, protocol);
.EE
.in
-.PP
+.P
Valid socket types include
.B SOCK_STREAM
to open a stream socket,
@@ -79,7 +79,7 @@ to open a datagram socket, and
to open a
.BR raw (7)
socket to access the IP protocol directly.
-.PP
+.P
.I protocol
is the IP protocol in the IP header to be received or sent.
Valid values for
@@ -107,12 +107,12 @@ stream sockets; and
for
.BR udplite (7)
datagram sockets.
-.PP
+.P
For
.B SOCK_RAW
you may specify a valid IANA IP protocol defined in
RFC\ 1700 assigned numbers.
-.PP
+.P
When a process wants to receive new incoming packets or connections, it
should bind a socket to a local interface address using
.BR bind (2).
@@ -134,7 +134,7 @@ is called on an unbound socket, the socket is automatically bound
to a random free port or to a usable shared port with the local address
set to
.BR INADDR_ANY .
-.PP
+.P
A TCP local socket address that has been bound is unavailable for
some time after closing, unless the
.B SO_REUSEADDR
@@ -151,7 +151,7 @@ and
On raw sockets
.I sin_port
is set to the IP protocol.
-.PP
+.P
.in +4n
.EX
struct sockaddr_in {
@@ -166,7 +166,7 @@ struct in_addr {
};
.EE
.in
-.PP
+.P
.I sin_family
is always set to
.BR AF_INET .
@@ -190,7 +190,7 @@ port, they are implemented only by higher protocols like
.BR tcp (7)
and
.BR udp (7).
-.PP
+.P
.I sin_addr
is the IP host address.
The
@@ -212,7 +212,7 @@ or set using the
.BR inet_makeaddr (3)
library functions or directly with the name resolver (see
.BR gethostbyname (3)).
-.PP
+.P
IPv4 addresses are divided into unicast, broadcast,
and multicast addresses.
Unicast addresses specify a single interface of a host,
@@ -224,7 +224,7 @@ socket flag is set.
In the current implementation, connection-oriented sockets are allowed
to use only unicast addresses.
.\" Leave a loophole for XTP @)
-.PP
+.P
Note that the address and the port are always stored in
network byte order.
In particular, this means that you need to call
@@ -275,7 +275,7 @@ Since Linux 5.14,
.\" commit 58fee5fc83658aaacf60246aeab738946a9ba516
it is treated as an ordinary unicast address
and can be assigned to an interface.
-.PP
+.P
Internet standards have traditionally also reserved various addresses
for particular uses, though Linux no longer treats
some of these specially.
@@ -314,7 +314,7 @@ The socket option level for IP is
.BR IPPROTO_IP .
.\" or SOL_IP on Linux
A boolean integer flag is zero when it is false, otherwise true.
-.PP
+.P
When an invalid socket option is specified,
.BR getsockopt (2)
and
@@ -607,7 +607,7 @@ IP_PMTUDISC_DONT:Never do Path MTU Discovery.
IP_PMTUDISC_DO:Always do Path MTU Discovery.
IP_PMTUDISC_PROBE:Set DF but ignore Path MTU.
.TE
-.sp 1
+.IP
When PMTU discovery is enabled, the kernel automatically keeps track of
the path MTU per destination host.
When it is connected to a specific peer with
@@ -828,6 +828,10 @@ is not zero, the primary local address of the interface specified by the
index overwrites
.I ipi_spec_dst
for the routing table lookup.
+.IP
+Not supported for
+.B SOCK_STREAM
+sockets.
.TP
.BR IP_RECVERR " (since Linux 2.2)"
.\" Precisely: since Linux 2.1.15
@@ -989,6 +993,9 @@ in which the kernel returns the original destination address
of the datagram being received.
The ancillary message contains a
.IR "struct sockaddr_in" .
+Not supported for
+.B SOCK_STREAM
+sockets.
.TP
.BR IP_RECVTOS " (since Linux 2.2)"
.\" Precisely: since Linux 2.1.68
@@ -998,6 +1005,9 @@ ancillary message is passed with incoming packets.
It contains a byte which specifies the Type of Service/Precedence
field of the packet header.
Expects a boolean integer flag.
+Not supported for
+.B SOCK_STREAM
+sockets.
.TP
.BR IP_RECVTTL " (since Linux 2.2)"
.\" Precisely: since Linux 2.1.68
@@ -1015,6 +1025,9 @@ Identical to
.BR IP_RECVOPTS ,
but returns raw unprocessed options with timestamp and route record
options not filled in for this hop.
+Not supported for
+.B SOCK_STREAM
+sockets.
.TP
.BR IP_ROUTER_ALERT " (since Linux 2.2)"
.\" Precisely: since Linux 2.1.68
@@ -1287,7 +1300,9 @@ Time in seconds to keep an IPv6 fragment in memory.
Regeneration interval (in seconds) of the hash secret (or lifetime
for the hash secret) for IPv6 fragments.
.TP
-.IR ipfrag_high_thresh " (integer), " ipfrag_low_thresh " (integer)"
+.IR ipfrag_high_thresh " (integer)"
+.TQ
+.IR ipfrag_low_thresh " (integer)"
If the amount of queued IP fragments reaches
.IR ipfrag_high_thresh ,
the queue is pruned down to
@@ -1305,7 +1320,7 @@ All ioctls described in
.BR socket (7)
apply to
.BR ip .
-.PP
+.P
Ioctls to configure generic device parameters are described in
.BR netdevice (7).
.\" FIXME Add a discussion of multicasting
@@ -1365,7 +1380,9 @@ was called on an already connected socket.
.B EMSGSIZE
Datagram is bigger than an MTU on the path and it cannot be fragmented.
.TP
-.BR ENOBUFS ", " ENOMEM
+.B ENOBUFS
+.TQ
+.B ENOMEM
Not enough free memory.
This often means that the memory allocation is limited by the socket
buffer limits, not by the system memory, but this is not 100% consistent.
@@ -1393,7 +1410,7 @@ The connection was unexpectedly closed or shut down by the other end.
.TP
.B ESOCKTNOSUPPORT
The socket is not configured or an unknown socket type was requested.
-.PP
+.P
Other errors may be generated by the overlaying protocols; see
.BR tcp (7),
.BR raw (7),
@@ -1415,7 +1432,7 @@ and
are Linux-specific.
.\" IP_XFRM_POLICY is Linux-specific
.\" IP_IPSEC_POLICY is a nonstandard extension, also present on some BSDs
-.PP
+.P
Be very careful with the
.B SO_BROADCAST
option \- it is not privileged in Linux.
@@ -1428,7 +1445,7 @@ See RFC 6762 for an example of a protocol (mDNS)
using the more modern multicast approach
to communicating with an open-ended
group of hosts on the local network.
-.PP
+.P
Some other BSD sockets implementations provide
.B IP_RCVDSTADDR
and
@@ -1438,7 +1455,7 @@ received datagrams.
Linux has the more general
.B IP_PKTINFO
for the same task.
-.PP
+.P
Some BSD sockets implementations also provide an
.B IP_RECVTTL
option, but an ancillary message with type
@@ -1447,13 +1464,13 @@ is passed with the incoming packet.
This is different from the
.B IP_TTL
option used in Linux.
-.PP
+.P
Using the
.B SOL_IP
socket options level isn't portable; BSD-based stacks use the
.B IPPROTO_IP
level.
-.PP
+.P
.B INADDR_ANY
(0.0.0.0) and
.B INADDR_BROADCAST
@@ -1476,7 +1493,7 @@ address structure for generic link layer information instead of the old
.BR sockaddr_pkt .
.SH BUGS
There are too many inconsistent error values.
-.PP
+.P
The error used to diagnose exhaustion of the ephemeral port range differs
across the various system calls
.RB ( connect (2),
@@ -1484,14 +1501,14 @@ across the various system calls
.BR listen (2),
.BR sendto (2))
that can assign ephemeral ports.
-.PP
+.P
The ioctls to configure IP-specific interface options and ARP tables are
not described.
-.\" .PP
+.\" .P
.\" Some versions of glibc forget to declare
.\" .IR in_pktinfo .
.\" Workaround currently is to copy it into your program from this man page.
-.PP
+.P
Receiving the original destination address with
.B MSG_ERRQUEUE
in
@@ -1515,10 +1532,10 @@ does not work in some Linux 2.2 kernels.
.BR tcp (7),
.BR udp (7),
.BR ip (8)
-.PP
+.P
The kernel source file
.IR Documentation/networking/ip\-sysctl.txt .
-.PP
+.P
RFC\ 791 for the original IP specification.
RFC\ 1122 for the IPv4 host requirements.
RFC\ 1812 for the IPv4 router requirements.