.\" -*- nroff -*- .\" macros .de EX \" Begin Example . IP . ft CW . nf . ne \\$1 .. .de EE \" End Example . ft P . fi . PP .. .TH INTERFACES 5 "5 April 2004" "ifupdown" "File formats" .SH NAME /etc/network/interfaces \- network interface configuration for ifup and ifdown .SH DESCRIPTION /etc/network/interfaces contains network interface configuration information for the .BR ifup (8) and .BR ifdown (8) commands. This is where you configure how your system is connected to the network. .P Lines starting with `#' are ignored. Note that end-of-line comments are NOT supported, comments must be on a line of their own. .P A line may be extended across multiple lines by making the last character a backslash. .P The file consists of zero or more "iface", "mapping", "auto", "allow-", "source" and "source-directory" stanzas. Here is an example. .EX auto eth0 allow-hotplug eth1 source interfaces.d/machine\-dependent source-directory interfaces.d mapping eth0 script /usr/local/sbin/map\-scheme map HOME eth0\-home map WORK eth0\-work iface eth0\-home inet static address 192.168.1.1 netmask 255.255.255.0 up flush\-mail iface eth0\-work inet dhcp iface eth1 inet dhcp .EE Lines beginning with the word "auto" are used to identify the physical interfaces to be brought up when .B ifup is run with the .B \-a option. (This option is used by the system boot scripts.) Physical interface names should follow the word "auto" on the same line. There can be multiple "auto" stanzas. .B ifup brings the named interfaces up in the order listed. .P Lines beginning with "allow-" are used to identify interfaces that should be brought up automatically by various subsytems. This may be done using a command such as "ifup \-\-allow=hotplug eth0 eth1", which will only bring up eth0 or eth1 if it is listed in an "allow-hotplug" line. Note that "allow-auto" and "auto" are synonyms. .P Lines beginning with "source" are used to include stanzas from other files, so configuration can be split into many files. The word "source" is followed by the path of file to be sourced. Shell wildcards can be used. (See .BR wordexp (3) for details.) .P Similarly, "source-directory" keyword is used to source multiple files at once, without specifying them individually or using shell globs. Additionally, when "source-directory" is used, names of the files are checked to match the following regular expression: \fI^[a\-zA\-Z0\-9_\-]+$\fR. In other words, the names must consist entirely of ASCII upper- and lower-case letters, ASCII digits, ASCII underscores, and ASCII minus-hyphens. In the directory path, shell wildcards may be used as well. .P When sourcing files or directories, if a path doesn't have a leading slash, it's considered relative to the directory containing the file in which the keyword is placed. In the example above, if the file is located at .IR /etc/network/interfaces\fR, paths to the included files are understood to be under .IR /etc/network\fR. .P Currently, "source-directory" isn't supported by .BR network-manager " and" .BR guessnet . .P By default, on a freshly installed Debian system, the interfaces file includes a line to source files in the .IR /etc/network/interfaces.d directory. .P Stanzas beginning with the word "mapping" are used to determine how a logical interface name is chosen for a physical interface that is to be brought up. The first line of a mapping stanza consists of the word "mapping" followed by a pattern in shell glob syntax. Each mapping stanza must contain a .BR script definition. The named script is run with the physical interface name as its argument and with the contents of all following "map" lines (\fBwithout\fR the leading "map") in the stanza provided to it on its standard input. The script must print a string on its standard output before exiting. See .IR /usr/share/doc/ifupdown/examples for examples of what the script must print. .P Mapping a name consists of searching the remaining mapping patterns and running the script corresponding to the first match; the script outputs the name to which the original is mapped. .P .B ifup is normally given a physical interface name as its first non\-option argument. .B ifup also uses this name as the initial logical name for the interface unless it is accompanied by a suffix of the form \fI=LOGICAL\fR, in which case ifup chooses \fILOGICAL\fR as the initial logical name for the interface. It then maps this name, possibly more than once according to successive mapping specifications, until no further mappings are possible. If the resulting name is the name of some defined logical interface then .B ifup attempts to bring up the physical interface as that logical interface. Otherwise .B ifup exits with an error. .P Stanzas defining logical interfaces start with a line consisting of the word "iface" followed by the name of the logical interface. In simple configurations without mapping stanzas this name should simply be the name of the physical interface to which it is to be applied. (The default mapping script is, in effect, the .B echo command.) The interface name is followed by the name of the address family that the interface uses. This will be "inet" for TCP/IP networking, but there is also some support for IPX networking ("ipx"), and IPv6 networking ("inet6"). Following that is the name of the method used to configure the interface. .P Additional options can be given on subsequent lines in the stanza. Which options are available depends on the family and method, as described below. Additional options can be made available by other Debian packages. For example, the wireless\-tools package makes available a number of options prefixed with "wireless\-" which can be used to configure the interface using .BR iwconfig (8) . (See .BR wireless (7) for details.) .P Options are usually indented for clarity (as in the example above) but are not required to be. .P .SH VLAN AND BRIDGE INTERFACES To ease the configuration of VLAN interfaces, interfaces having .B . (full stop character) in the name are configured as 802.1q tagged virtual LAN interface. For example, interface .B eth0.1 is a virtual interface having .B eth0 as physical link, with VLAN ID 1. .P For compatibility with .B bridge-utils package, if .B bridge_ports option is specified, VLAN interface configuration is .B not performed. .SH IFACE OPTIONS The following "command" options are available for every family and method. Each of these options can be given multiple times in a single stanza, in which case the commands are executed in the order in which they appear in the stanza. (You can ensure a command never fails by suffixing them with "|| true".) .TP .BI pre\-up " command" Run .I command before bringing the interface up. If this command fails then .B ifup aborts, refraining from marking the interface as configured, prints an error message, and exits with status 0. This behavior may change in the future. .TP .BI up " command" .TP .BI post\-up " command" Run .I command after bringing the interface up. If this command fails then .B ifup aborts, refraining from marking the interface as configured (even though it has really been configured), prints an error message, and exits with status 0. This behavior may change in the future. .TP .BI down " command" .TP .BI pre\-down " command" Run .I command before taking the interface down. If this command fails then .B ifdown aborts, marks the interface as deconfigured (even though it has not really been deconfigured), and exits with status 0. This behavior may change in the future. .TP .BI post\-down " command" Run .I command after taking the interface down. If this command fails then .B ifdown aborts, marks the interface as deconfigured, and exits with status 0. This behavior may change in the future. .P There exists for each of the above mentioned options a directory .IR /etc/network/if\-\fB