280 lines
7.9 KiB
Groff
280 lines
7.9 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" From: @(#)inet.4 8.1 (Berkeley) 6/5/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd Feb 4, 2016
|
|
.Dt INET 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm inet
|
|
.Nd Internet protocol family
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In netinet/in.h
|
|
.Sh DESCRIPTION
|
|
The Internet protocol family is a collection of protocols
|
|
layered atop the
|
|
.Em Internet Protocol
|
|
.Pq Tn IP
|
|
transport layer, and utilizing the Internet address format.
|
|
The Internet family provides protocol support for the
|
|
.Dv SOCK_STREAM , SOCK_DGRAM ,
|
|
and
|
|
.Dv SOCK_RAW
|
|
socket types; the
|
|
.Dv SOCK_RAW
|
|
interface provides access to the
|
|
.Tn IP
|
|
protocol.
|
|
.Sh ADDRESSING
|
|
Internet addresses are four byte quantities, stored in
|
|
network standard format (on little endian machines, such as the
|
|
.Tn alpha ,
|
|
.Tn amd64
|
|
and
|
|
.Tn i386
|
|
these are word and byte reversed).
|
|
The include file
|
|
.In netinet/in.h
|
|
defines this address
|
|
as a discriminated union.
|
|
.Pp
|
|
Sockets bound to the Internet protocol family utilize
|
|
the following addressing structure,
|
|
.Bd -literal -offset indent
|
|
struct sockaddr_in {
|
|
uint8_t sin_len;
|
|
sa_family_t sin_family;
|
|
in_port_t sin_port;
|
|
struct in_addr sin_addr;
|
|
char sin_zero[8];
|
|
};
|
|
.Ed
|
|
.Pp
|
|
Sockets may be created with the local address
|
|
.Dv INADDR_ANY
|
|
to affect
|
|
.Dq wildcard
|
|
matching on incoming messages.
|
|
The address in a
|
|
.Xr connect 2
|
|
or
|
|
.Xr sendto 2
|
|
call may be given as
|
|
.Dv INADDR_ANY
|
|
to mean
|
|
.Dq this host .
|
|
The distinguished address
|
|
.Dv INADDR_BROADCAST
|
|
is allowed as a shorthand for the broadcast address on the primary
|
|
network if the first network configured supports broadcast.
|
|
.Sh PROTOCOLS
|
|
The Internet protocol family is comprised of
|
|
the
|
|
.Tn IP
|
|
network protocol, Internet Control
|
|
Message Protocol
|
|
.Pq Tn ICMP ,
|
|
Internet Group Management Protocol
|
|
.Pq Tn IGMP ,
|
|
Transmission Control
|
|
Protocol
|
|
.Pq Tn TCP ,
|
|
and User Datagram Protocol
|
|
.Pq Tn UDP .
|
|
.Tn TCP
|
|
is used to support the
|
|
.Dv SOCK_STREAM
|
|
abstraction while
|
|
.Tn UDP
|
|
is used to support the
|
|
.Dv SOCK_DGRAM
|
|
abstraction.
|
|
A raw interface to
|
|
.Tn IP
|
|
is available
|
|
by creating an Internet socket of type
|
|
.Dv SOCK_RAW .
|
|
The
|
|
.Tn ICMP
|
|
message protocol is accessible from a raw socket.
|
|
.Pp
|
|
The
|
|
.Nm
|
|
address on an interface consist of the address itself, the
|
|
netmask, either broadcast address in case of a broadcast
|
|
interface or peers address in case of point-to-point interface.
|
|
The following
|
|
.Xr ioctl 2
|
|
commands are provided for a datagram socket in the Internet domain:
|
|
.Pp
|
|
.Bl -tag -width ".Dv SIOCGIFBRDADDR" -offset indent -compact
|
|
.It Dv SIOCAIFADDR
|
|
Add address to an interface.
|
|
The command requires
|
|
.Ft struct in_aliasreq
|
|
as argument.
|
|
.It Dv SIOCDIFADDR
|
|
Delete address from an interface.
|
|
The command requires
|
|
.Ft struct ifreq
|
|
as argument.
|
|
.It Dv SIOCGIFADDR
|
|
.It Dv SIOCGIFBRDADDR
|
|
.It Dv SIOCGIFDSTADDR
|
|
.It Dv SIOCGIFNETMASK
|
|
Return address information from interface.
|
|
The returned value is in
|
|
.Ft struct ifreq .
|
|
This way of address information retrieval is obsoleted, a
|
|
preferred way is to use
|
|
.Xr getifaddrs 3
|
|
API.
|
|
.El
|
|
.Ss MIB Variables
|
|
A number of variables are implemented in the net.inet branch of the
|
|
.Xr sysctl 3
|
|
MIB.
|
|
In addition to the variables supported by the transport protocols
|
|
(for which the respective manual pages may be consulted),
|
|
the following general variables are defined:
|
|
.Bl -tag -width IPCTL_ACCEPTSOURCEROUTE
|
|
.It Dv IPCTL_FORWARDING
|
|
.Pq ip.forwarding
|
|
Boolean: enable/disable forwarding of IP packets.
|
|
Defaults to off.
|
|
.It Dv IPCTL_SENDREDIRECTS
|
|
.Pq ip.redirect
|
|
Boolean: enable/disable sending of ICMP redirects in response to
|
|
.Tn IP
|
|
packets for which a better, and for the sender directly reachable, route
|
|
and next hop is known.
|
|
Defaults to on.
|
|
.It Dv IPCTL_DEFTTL
|
|
.Pq ip.ttl
|
|
Integer: default time-to-live
|
|
.Pq Dq TTL
|
|
to use for outgoing
|
|
.Tn IP
|
|
packets.
|
|
.It Dv IPCTL_ACCEPTSOURCEROUTE
|
|
.Pq ip.accept_sourceroute
|
|
Boolean: enable/disable accepting of source-routed IP packets (default false).
|
|
.It Dv IPCTL_SOURCEROUTE
|
|
.Pq ip.sourceroute
|
|
Boolean: enable/disable forwarding of source-routed IP packets (default false).
|
|
.It Va ip.process_options
|
|
Integer: control IP options processing.
|
|
By setting this variable to 0, all IP options in the incoming packets
|
|
will be ignored, and the packets will be passed unmodified.
|
|
By setting to 1, IP options in the incoming packets will be processed
|
|
accordingly.
|
|
By setting to 2, an
|
|
.Tn ICMP
|
|
.Dq "prohibited by filter"
|
|
message will be sent back in response to incoming packets with IP options.
|
|
Default is 1.
|
|
This
|
|
.Xr sysctl 8
|
|
variable affects packets destined for a local host as well as packets
|
|
forwarded to some other host.
|
|
.It Va ip.rfc6864
|
|
Boolean: control IP IDs generation behaviour.
|
|
True value enables RFC6864 support, which specifies that IP ID field of
|
|
.Em atomic
|
|
datagrams can be set to any value.
|
|
The
|
|
.Fx implementation sets it to zero.
|
|
Enabled by default.
|
|
.It Va ip.random_id
|
|
Boolean: control IP IDs generation behaviour.
|
|
Setting this
|
|
.Xr sysctl 8
|
|
to 1 causes the ID field in
|
|
.Em non-atomic
|
|
IP datagrams (or all IP datagrams, if
|
|
.Va ip.rfc6864
|
|
is disabled) to be randomized instead of incremented by 1 with each packet
|
|
generated.
|
|
This closes a minor information leak which allows remote observers to
|
|
determine the rate of packet generation on the machine by watching the
|
|
counter.
|
|
At the same time, on high-speed links, it can decrease the ID reuse
|
|
cycle greatly.
|
|
Default is 0 (sequential IP IDs).
|
|
IPv6 flow IDs and fragment IDs are always random.
|
|
.It Va ip.maxfragpackets
|
|
Integer: maximum number of fragmented packets the host will accept and hold
|
|
in the reassembling queue simultaneously.
|
|
0 means that the host will not accept any fragmented packets.
|
|
\-1 means that the host will accept as many fragmented packets as it receives.
|
|
.It Va ip.maxfragsperpacket
|
|
Integer: maximum number of fragments the host will accept and hold
|
|
in the reassembling queue for a packet.
|
|
0 means that the host will not accept any fragmented packets.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr ioctl 2 ,
|
|
.Xr socket 2 ,
|
|
.Xr getifaddrs 3 ,
|
|
.Xr sysctl 3 ,
|
|
.Xr icmp 4 ,
|
|
.Xr intro 4 ,
|
|
.Xr ip 4 ,
|
|
.Xr ipfirewall 4 ,
|
|
.Xr route 4 ,
|
|
.Xr tcp 4 ,
|
|
.Xr udp 4 ,
|
|
.Xr pfil 9
|
|
.Rs
|
|
.%T "An Introductory 4.3 BSD Interprocess Communication Tutorial"
|
|
.%B PS1
|
|
.%N 7
|
|
.Re
|
|
.Rs
|
|
.%T "An Advanced 4.3 BSD Interprocess Communication Tutorial"
|
|
.%B PS1
|
|
.%N 8
|
|
.Re
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
protocol interface appeared in
|
|
.Bx 4.2 .
|
|
The
|
|
.Dq protocol cloning
|
|
code appeared in
|
|
.Fx 2.1 .
|
|
.Sh CAVEATS
|
|
The Internet protocol support is subject to change as
|
|
the Internet protocols develop.
|
|
Users should not depend
|
|
on details of the current implementation, but rather
|
|
the services exported.
|