> > > > > Also the arpwatch program might help if you are trying to track down > > > mysterious devices popping up on your network. > > > > > > > +1 for arpwatch > > > > You beat me to mentioning it. ;) > > Arpwatch is nice and in the syslog the unusual system would be called out as a bogon assuming a different network scope... If it didn't have regular attempted communication though you'll still need a way of 'enticing' it into doing so... And until it's understood what arpwatch is doing (or for targeted as opposed to automated alerts) still think that manual investigation with tcpdump and wireshark would be more beneficial... > > Perhaps a stupid idea: I didn't see where the OP indicated they did not > know which physical machine this is, but I understood it to be unknown > on the network. > > So, if I"m right, just go to the machine and do ifconfig or similar. > I think the safe assumption is this would not be possible or at the least was not the point of the OP given that he was looking for a tool on a CentOS server to do this...