[CentOS] how to find unknown ip address?

Running 'arp -n' on a machine that you think might receive packets from the
unknown host might also do the job.

K

Kahlil (Kal) Hodgson                       GPG: C9A02289
Head of Technology                         (m) +61 (0) 4 2573 0382
DealMax Pty Ltd                            (w) +61 (0) 3 9008 5281

Suite 1415
401 Docklands Drive
Docklands VIC 3008 Australia

"All parts should go together without forcing.  You must remember that
the parts you are reassembling were disassembled by you.  Therefore,
if you can't get them together again, there must be a reason.  By all
means, do not use a hammer."  -- IBM maintenance manual, 19