$ ifconfig
…
eth1 Link encap:Ethernet HWaddr 08:00:27:c5:d3:68
inet addr:172.20.20.174 Bcast:172.20.20.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fec5:d368/64 Scope:Link
…
eth2 Link encap:Ethernet HWaddr 08:00:27:5d:86:7b
inet addr:172.20.20.83 Bcast:172.20.20.255 Mask:255.255.255.0
inet6 addr: fe80::a00:27ff:fe5d:867b/64 Scope:Link
…
$ sudo ifconfig eth1 down
$ sudo ifconfig eth2 down