хм
ifconfig eth1 192.168.1.1 netmask 255.255.255.0 up
проверяем
ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_req=1 ttl=64 time=0.127 ms
64 bytes from 192.168.1.1: icmp_req=2 ttl=64 time=0.091 ms
^C
--- 192.168.1.1 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.091/0.109/0.127/0.018 ms
работает, хотя даже кабель не воткнут