# tcpdump -i eth1
tcpdump: bind: Network is down
# ifconfig eth1 up promisc
# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:DE:AD:BE:EF:00  
          UP BROADCAST PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
          Interrupt:11 Base address:0x1c80 

# /usr/sbin/tcpdump -i eth1
tcpdump: WARNING: eth1: no IPv4 address assigned
tcpdump: listening on eth1
