INTERFACES(S) File formats INTERFACES(S) NAME /etc/network/interfaces - network interface configuration for ifup and ifdown DESCRIPTION /etc/network/interfaces contains network interface config- uration information for the ifup(p) and ifdown(n) com- mands. This is where you configure how your system is con- nected to the network, by setting IP addresses, and other related information. The file can contain comments; all lines starting with `#' are ignored. A line may be extended across multiple lines by making the last character a \ in the usual manner. The file consists of zero or more "iface", "mapping" and "auto" stanzas, each of which defines one network inter- face. Here are some sample stanzas: auto lo eth0 iface lo inet loopback 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 iface eth0-work inet dhcp Stanzas beginning with the word "auto" are used to iden- tify interfaces that should be brought up automatically on system boot. Interface names should follow the word "auto" on the same line. Multiple "auto" stanzas may be used, or they may be combined into a single line. Stanzas beginning with the word "mapping" are used to automatically translate a physical interface name into a logical interface specified by an "iface" stanza. The first line of a mapping stanza begins with the word "map- ping" followed by the names of each physical interface this mapping should apply to. Shell globs (* and ? wild- cards) may be used when specifying interfaces. Each map- ping must specify a script, which will be run when the mapping is applied. In addition, a mapping may specify any number of "map" parameters that will be passed to the script. Stanzas defining interfaces start with the word "iface". The next word is the name of the interface, as used by the ifconfig(g) or route(e) commands (ie, things like "lo", "eth0", or "ppp0", and "eth1:0"). The interface name is followed by address family the interface uses -- generally this will be "inet" for TCP/IP networking, but there is also some support for IPX net- working ("ipx"), and IPv6 networking ("inet6"). Following that is the method used to configure the inter- face. In the example above, this is "static", which means that eth0 is a staticly allocated IPv4 address. Further options may follow the "iface" header line on additional lines in the stanza. These are usually indented for clarity (as in the example) but are not required to be. IFACE OPTIONS There are currently three standard options available for all interfaces, regardless of address family or method. These are: up command Run command after bringing the interface up. This option can be given multiple times for a single interface. If so, the commands will be executed in order. If one of the commands fails, none of the others will be executed, but the interface will remain configured. (You can ensure a command never fails by suffixing "|| true".) pre-up command Run command before bringing the interface up. This option can be given multiple times for a single interface. If so, the commands will be executed in order. If one of the commands fails, none of the others will be executed, and the interface will not be configured. (You can ensure a command never fails by suffixing "|| true".) down command Run command before taking the interface down. This option can be given multiple times for a single interface. If so, the commands will be executed in order. If one of the commands fails, none of the others will be executed, and the interface will not be deconfigured. (You can ensure a command never fails by suffixing "|| true".) post-down command Run command after taking the interface down. This option can be given multiple times for a single interface. If so, the commands will be executed in order. If one of the commands fails, none of the others will be executed, but the interface will remain deconfigured. (You can ensure a command never fails by suffixing "|| true".) Most methods require additional information, such as address, and netmask; details about the available methods and the information they require follows. INET ADDRESS FAMILY This section documents the methods available in the inet address family. The loopback Method This method may be used to define the IPv4 loopback inter- face. Options (No options) The static Method This method may be used to define ethernet interfaces with statically allocated IPv4 addresses. Options address address Address (dotted quad) required netmask netmask Netmask (dotted quad) required broadcast broadcast_address Broadcast address (dotted quad) network network_address Network address (dotted quad) required for 2.0.x kernels gateway address Default gateway (dotted quad) pointopoint address Address of other end point (dotted quad). Note the spelling of "point-to". The dhcp Method This method may be used to obtain an address via DHCP with any of the tools: dhclient, pump (2.2.x kernels only), or dhcpcd. If you have a complicated DHCP setup you should note that some of these clients use their own configura- tion files, rather than obtaining their configuration via *ifup*. Options hostname hostname Hostname to be requested (pump, dhcpcd) leasehours leastime Preferred lease time in hours (pump) leasetime leasetime Preferred lease time in seconds (dhcpcd) vendor vendor Vendor class identifier (dhcpcd) client client_id Client identifier (dhcpcd) The bootp Method This method may be used to obtain an address via bootp. Options bootfile file Tell the server to use file as the bootfile. server address Use the IP address address to communicate with the server. hwaddr addr Use addr as the hardware address instead of whatever it really is. The ppp Method This method uses pon/poff to configure a PPP interface. See those commands for details. Options provider name Use name as the provider (from /etc/ppp/peers). The wvdial Method This method uses wvdial to configure a PPP interface. See that command for ore details. Options provider name Use name as the provider (from /etc/ppp/peers). IPX ADDRESS FAMILY This section documents the methods available in the ipx address family. The static Method This method may be used to setup an IPX interface. Options frame netnum The dynamic Method This method may be used to setup an IPX interface dynami- cally. Options frame INET6 ADDRESS FAMILY This section documents the methods available in the inet6 address family. The loopback Method This method may be used to define the IPv6 loopback inter- face. Options (No options) The static Method This method may be used to define interfaces with stati- cally assigned IPv6 addresses. Options address address Address (colon delimited) required netmask mask Netmask (number of bits, eg 64) required gateway address Default gateway (colon delimited) The v4tunnel Method This method may be used to setup an IPv6-over-IPv4 tunnel. It requires the ip command from the iproute package. Options address address Address (colon delimited) required netmask mask Netmask (number of bits, eg 64) required endpoint address Address of other tunnel endpoint (IPv4 dot- ted quad) required gateway address Default gateway (colon delimited) AUTHOR The ifupdown suite was written by Anthony Towns <aj@azure.humbug.org.au>. This manpage was contributed by Joey Hess <joey@kitenet.net> SEE ALSO ifup(p), ifdown(n) ifupdown August 10 2000 INTERFACES(S)