tcpdump to watch *other* machines

From: wlcna (wlcna_at_nospam.com)
Date: 08/30/03 

Date: Sat, 30 Aug 2003 18:18:56 GMT

I'm trying to watch http traffic initiated from machine A on a LAN from
machine B on same LAN, a linux box. This is mostly for convenience so I
don't need to install extra stuff on machine A. This is a simple home
LAN, not a business. I tried,

tcpdump 'dst port 80'

and

tcpdump 'tcp port 80'

and in either case only saw traffic where the linux machine was involved.

So I thought, duh, maybe it's because I have a switch and not a hub, since
the purpose of a switch is to *not* send packets not involving a machine
down *all* the wires like a hub does, right? Is that the only problem?
This is something tcpdump is supposed to be able to do, right? (I.e.
assuming a simple, cheap hub or old-fashioned coax ethernet "backbone"
type connections.)

Relevant Pages

  • Re: tcpdump to watch *other* machines
    ... ]machine B on same LAN, ... ]tcpdump 'dst port 80' ... ]and in either case only saw traffic where the linux machine was involved. ... ]So I thought, duh, maybe it's because I have a switch and not a hub, since ...
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