Bem, vamos adicionar uma placa de rede eth0 no arquivo interfaces.
Vou usar o editor de texto VIM.

Vamos abrir o arquivo interfaces:
# vim /etc/network/interfaces

Agora, com o arquivo aberto, vamos adicionar no final do arquivo a placa de rede eth0:

auto eth0
iface eth0 inet static
address 192.168.0.155
netmask 255.255.255.0
broadcast 192.168.0.255
network 192.168.0.1


Agora, salve e feche o arquivo, clicando no botão ESC, depois, digite :x e tecle ENTER.

Vamos reiniciar o serviçoe ver se funcionou:
/etc/init.d/networking restart


Vai aparecer algo assim:

damasceno:/# /etc/init.d/networking restart
Reconfiguring network interfaces...There is already a pid file /var/run/dhclient.eth0.pid with pid 1644
killed old client process, removed PID file
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

Listening on LPF/eth0/00:15:58:b2:09:d1
Sending on LPF/eth0/00:15:58:b2:09:d1
Sending on Socket/fallback
DHCPRELEASE on eth0 to 192.168.0.1 port 67
Internet Systems Consortium DHCP Client V3.1.1
Copyright 2004-2008 Internet Systems Consortium.
All rights reserved.
For info, please visit http://www.isc.org/sw/dhcp/

Listening on LPF/eth0/00:15:58:b2:09:d1
Sending on LPF/eth0/00:15:58:b2:09:d1
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.0 port 67 interval 8
DHCPOFFER from 192.168.0.1
DHCPREQUEST on eth0 to 255.255.255.0 port 67
DHCPACK from 192.168.0.1
bound to 192.168.0.155 -- renewal in 124576 seconds.
done.


Então, ocorreu tudo bem, e está funcionando :)