.\"	$FabBSD$
.\"	$OpenBSD: hostname.if.5,v 1.52 2008/01/31 20:00:08 jmc Exp $
.\"	$NetBSD: hosts.5,v 1.4 1994/11/30 19:31:20 jtc Exp $
.\"
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.\"     @(#)hosts.5	8.2 (Berkeley) 12/11/93
.\"
.Dd $Mdocdate: January 31 2008 $
.Dt HOSTNAME.IF 5
.Os
.Sh NAME
.Nm hostname.if
.Nd interface-specific configuration files
.Sh DESCRIPTION
The
.Nm hostname.*\&
file contains information regarding the configuration of each network interface.
One file should exist for each interface that is to be configured, such as
.Pa hostname.fxp0 .
However, a configuration file is not needed for lo0.
.Pp
Arguments containing either whitespace or single quote
characters must be double quoted.
For example:
.Bd -literal -offset indent
inet 10.0.0.1 255.255.255.0 10.0.0.255 description "Bob's uplink"
.Ed
.Sh STATIC ADDRESS CONFIGURATION
The following three
.Nm hostname.*\&
formats are valid for configuring network interfaces with static
addresses:
.Pp
Regular IPv4 network setup:
.Bd -ragged -offset indent
.Li inet
.Op Li alias
.Va addr
.Va netmask
.Va broadcast_addr
.Va options
.br
.Li dest
.Va dest_addr
.Ed
.Pp
Regular IPv6 network setup:
.Bd -ragged -offset indent
.Li inet6
.Op Li alias
.Va addr
.Va prefixlen
.Va options
.br
.Li dest
.Va dest_addr
.Ed
.Pp
Other network setup:
.Bd -ragged -offset indent
.Va addr_family
.Va options
.Ed
.Pp
A typical file contains only one line, but more extensive files are possible,
for example:
.Bd -literal -offset 1n
inet 10.0.1.12 255.255.255.0 10.0.1.255 media 100baseTX description Uplink
inet alias 10.0.1.13 255.255.255.255 10.0.1.13
inet alias 10.0.1.14 255.255.255.255 NONE
inet alias 10.0.1.15 255.255.255.255
inet alias 10.0.1.16 0xffffffff
# This is an example comment line.
inet6 alias fec0::1 64
inet6 alias fec0::2 64 anycast
.Ed
.Pp
The above formats have the following field values:
.Bl -tag -width indent -offset indent
.It Va addr_family
The address family of the interface, generally
.Dq inet
or
.Dq inet6 .
.It Li alias
The literal string
.Dq alias
if this is an additional network address for the interface.
.It Va addr
The optional address that belongs to the interface, such as
190.191.192.1 or fe80:2::1.
It is also feasible to use a hostname as specified in
.Pa /etc/hosts .
It is recommended that an address be used instead of symbolic information,
since the latter might activate
.Xr resolver 3
library routines.
.Pp
If no address is specified, the
.Va netmask ,
.Va broadcast_addr ,
.Li dest ,
and
.Va dest_addr
options are invalid and will be ignored.
.It Va netmask
The optional network mask for the interface, e.g.,
255.255.255.0.
If
.Va addr
is specified but
.Va netmask
is not, the classful mask based on
.Va addr
is used.
.It Va broadcast_addr
The optional broadcast address for the interface, e.g.,
190.191.192.255.
The word
.Dq NONE
can also be specified in order to configure the broadcast address based
on the
.Va netmask .
The
.Va netmask
option must be present in order to use this option.
.It Va options
Miscellaneous options to set on the interface, e.g.,
.Dq media 100baseTX mediaopt full-duplex .
Valid options for a particular interface type can be found in
.Xr ifconfig 8 .
When used, the
.Va netmask
and
.Va broadcast_addr
options must also be present.
.It Li dest
If the interface needs a destination address set, this is the literal text
.Dq dest .
As shown in the example, this declaration should start on a separate line.
.It Va dest_addr
The destination address to be set on the interface, such as
190.191.192.2.
It is also feasible to use a hostname as specified in
.Pa /etc/hosts .
It is recommended that an address be used instead of symbolic information
which might activate
.Xr resolver 3
library routines.
.It Va prefixlen
The prefixlen number, or number of bits in the netmask, to be set on
the interface, such as 64.
.It Li #
Comments are allowed.
Anything following a comment character is treated as a comment.
.It Li \&! Ns Ar command-line
Arbitrary shell commands can be executed using this directive.
Useful for doing interface-specific configuration such as
setting up custom routes using
.Xr route 8
or establishing tunnels using
.Xr ifconfig 8 .
It is worth noting that
.Dq \e$if
in a command line will be replaced by the interface name.
.El
.Sh DYNAMIC ADDRESS CONFIGURATION
The following
.Nm hostname.*\&
formats are valid for configuring network interfaces with dynamic
addresses:
.Pp
A DHCP-configured network interface setup consists of
.Bd -ragged -offset indent
.Li dhcp
.Va options
.Ed
.Pp
For example:
.Bd -literal -offset indent
dhcp media 100baseTX mediaopt full-duplex
.Ed
.Pp
The above format has the following field values:
.Bl -tag -width indent -offset indent
.It Li dhcp
The literal string
.Dq dhcp
if the interface is to be configured using DHCP.
See
.Xr dhclient 8
and
.Xr dhclient.conf 5
for more details.
.It Va options
Miscellaneous options to set on the interface, e.g.,
.Dq media 100baseTX mediaopt full-duplex .
Valid options for a particular interface type can be found in
.Xr ifconfig 8 .
The FabBSD installation script will create
.Nm hostname.if
with options of
.Dq NONE NONE NONE
when DHCP configuration is chosen.
This is the same as specifying just
.Dq dhcp .
.El
.Pp
IPv6 stateless address autoconfiguration:
.Bd -ragged -offset indent
.Li rtsol
.Va options
.Ed
.Pp
The above format has the following field values:
.Bl -tag -width indent -offset indent
.It Li rtsol
The literal string
.Dq rtsol
if the interface is to be configured using
IPv6 stateless address autoconfiguration.
This should be used on single interface hosts only,
since the IPv6 specifications are silent about the
behavior on multi-interface hosts.
Also note that the kernel must be configured to accept IPv6
router advertisement, and configured as a host (i.e. non-router).
Add the following lines into
.Xr sysctl.conf 5 :
.Bd -literal -offset indent
net.inet6.ip6.forwarding=0
net.inet6.ip6.accept_rtadv=1
.Ed
.It Va options
Miscellaneous options to set on the interface, e.g.,
.Dq media 100baseTX mediaopt full-duplex .
Valid options for a particular interface type can be found in
.Xr ifconfig 8 .
.El
.Sh ADDRESS-LESS CONFIGURATION
A network interface that does not require an IP address consists of
.Bd -ragged -offset indent
.Va state
.Va options
.Ed
.Pp
The above format has the following field values:
.Bl -tag -width indent -offset indent
.It Va state
The administrative state in which to put the interface, either
.Dq up
or
.Dq down .
.It Va options
Miscellaneous options to set on the interface, e.g.,
.Dq media 100baseTX mediaopt full-duplex .
Valid options for a particular interface type can be found in
.Xr ifconfig 8 .
.El
.Sh SEE ALSO
.Xr hosts 5 ,
.Xr dhcp 8 ,
.Xr ifconfig 8 ,
.Xr lmccontrol 8 ,
.Xr netstart 8 ,
.Xr rc 8