10.8.1 Triggering network configuration at boot time

On boot the /etc/rcS.d/S40networking init script runs the command ifup -a. This brings up all physical interfaces listed in auto stanzas in /etc/network/interfaces.

These days it is often better to handle network configuration using dynamic methods. Once mechanisms for supporting dynamically changing hardware are in place it becomes simplest to treat static hardware as if it were dynamic too. Booting can then be treated as just another hotplug event. (See Triggering network configuration – hotplug, Section 10.8.2.)

However, in almost all cases one wants at least the loopback interface lo to be brought up on boot. Therefore, make sure that /etc/network/interfaces includes the following stanzas.

     auto lo
     
     iface lo inet loopback

You can list additional physical interface names in auto stanzas if you want them to be brought up on boot too. Never list PCMCIA interfaces in auto stanzas. The PCMCIA cardmgr is started later in the boot sequence than when /etc/rcS.d/S40networking runs.