/etc/network/interfaces:
iface usb0
inet static
address 192.168.42.42
netmask 255.255.255.0
network 192.168.42.0
broadcast 192.168.42.255
/etc/udev/rules.d/85-ifupdown.rules
# This file causes network devices to be brought up or down as a result
# of hardware being added or removed, including that which isn't ordinarily
# removable.
# See udev(7) for syntax.
SUBSYSTEM=="net", GOTO="net_start"
GOTO="net_end"
LABEL="net_start"
# Bring devices up and down only if they're marked auto.
# Use start-stop-daemon so we don't wait on dhcp
ACTION=="add", RUN+="/sbin/start-stop-daemon --start --background --pidfile /var/run/network/bogus --startas /sbin/ifup -- --allow hotplug $env{INTERFACE}"
ACTION=="remove", RUN+="/sbin/start-stop-daemon --start --background --pidfile /var/run/network/bogus --startas /sbin/ifdown -- --allow hotplug $env{INTERFACE}"
LABEL="net_end"