bash# arpwatch bash# pine
The first command starts arpwatch, then the second one takes you into a mail reader. Press i to view your Inbox. Scroll to the bottom and wait for a few moments. When you think something might have happened press the down arrow a few times to see if any new messages are in you Inbox. Email messages should appear if you are on an active network. See if you have an email message with your gateway IP address. A message would look something like this:
Date: Thu, 14 Mar 2002 14:52:16 -1000 From: Arpwatch <email@example.com> To: firstname.lastname@example.org Subject: new station (dave.bob.org) hostname: dave.bob.org ip address: 220.127.116.11 ethernet address: 0:10:20:30:2:f2 ethernet vendor: Dell timestamp: Thursday, March 14, 2002 14:52:16 -1000
You should get a email message with the gateway's ethernet address. If you later get a different ethernet address you know that there might be another computer using the same IP address. It is also possible that the gateway machine has more than one ethernet address on the local network.