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.\"     @(#)hosts.5	8.2 (Berkeley) 12/11/93
.\"
.Dd $Mdocdate: March 10 2017 $
.Dt HOSTNAME.IF 5
.Os
.Sh NAME
.Nm hostname.if
.Nd interface-specific configuration files
.Sh DESCRIPTION
The
.Nm hostname.*\&
files contain 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
or
.Pa hostname.bridge0 .
A configuration file is not needed for lo0.
.Pp
The configuration information is expressed in a line-by-line packed format
which makes the most common cases simpler; those dense formats are described
below.
Any lines not matching these packed formats are passed directly to
.Xr ifconfig 8 .
The packed formats are converted using a somewhat inflexible parser and
the administrator should not expect magic \(em if in doubt study
.Xr ifconfig 8
and the
per-driver manual pages to see what arguments are permitted.
.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
.Pp
Each line is processed separately and in order.
For example:
.Bd -literal -offset indent
nwid mynwid
wpakey mywpakey
dhcp
.Ed
.Pp
would run ifconfig to set the nwid of the interface, run it again to set the wpakey of the interface, and then start
.Xr dhclient 8 .
.Sh STATIC ADDRESS CONFIGURATION
The following packed 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
!route add 65.65.65.65 10.0.1.13
up
.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
Arbitrary shell commands can be executed using this directive, as
long as they are available in the single-user environment (for
instance,
.Pa /bin
or
.Pa /sbin ) .
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 packed 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
The above format has the following field values:
.Bl -tag -width "optionsXXX" -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 .
.El
.Pp
IPv6 stateless address autoconfiguration:
.Bd -ragged -offset indent
.Li inet6 autoconf
.Va options
.Ed
.Pp
The above format has the following field values:
.Bl -tag -width "optionsXXX" -offset indent
.It Li inet6
The address family.
.It Li autoconf
The literal string
.Dq autoconf ,
to configure the interface
using IPv6 stateless address autoconfiguration (SLAAC).
.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 BRIDGE INTERFACE CONFIGURATION
If the network interface is a bridge, the options described in
the bridge section of the
.Xr ifconfig 8
manual page apply.
.Pp
For example:
.Bd -literal -offset indent
add fxp0
add ep1
-learn fxp0
#
!ipsecctl -F
#
static fxp0 8:0:20:1e:2f:2b
up    # and finally enable it
.Ed
.Sh FILES
.Bl -tag -width "/etc/hostname.XXXXXX"
.It Pa /etc/hostname.XXX
Interface-specific configuration files.
.El
.Sh SEE ALSO
.Xr hosts 5 ,
.Xr dhclient 8 ,
.Xr ifconfig 8 ,
.Xr netstart 8 ,
.Xr rc 8