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Using 'netstat -tulp' on my server box running under CentOS I have discovered strange listening ports 33363 (TCP) and 35661 (UDP). The thing is that 'PID/Program name' field for these ports contains nothing (dash actually). 'fuser -n tcp 33363' shows nothing. I have checked my box with chkrootkit and rkhunter utilities and it seems everything is O.K. Does anybody know what these sockets can be used for?

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Have you tried with lsof?

lsof -i TCP:33363
lsof -i UDP:35661
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Thanks for reply! Like 'fuser' 'lsof' gives an empty output. – user14241 Jul 24 '09 at 8:35
Pretty weird... You can also try to trace the pid and see if it shows something interesting: strace -p <PID> – Francisco Jul 24 '09 at 8:58
What PID, Fran? – innaM Jul 24 '09 at 9:24
Doh! True, we do not know the pid. Thanks for pointing it out Manni :) – Francisco Jul 24 '09 at 9:26

Did you run netstat -tulp as root?

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Sure. :) Thanks for suggestion! – user14241 Jul 24 '09 at 8:37
Could have been the reason for the missing pid. You never know ;-) – innaM Jul 24 '09 at 9:22

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