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What does -tnn mean in tcpdump -i eth0 -tnn dst port 80 -c 1000. I didn't find -tnn on the man page, and I didn't find it on the Internet. Can anyone explain it to me?

Searene
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1 Answers1

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You can often combine options into one combined one to make typing easier.

In this case:

-nn Don't convert protocol and port numbers etc. to names either.

-t Don't print a timestamp on each dump line.

This also implies

-n Don't convert host addresses to names. This can be used to avoid DNS lookups.

Community
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Sven
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  • Thank you, but it's weird that `-nn` isn't shown in my linux tcpdump man page. – Searene Oct 02 '15 at 13:27
  • I see it on EL6, EL7, but not on Ubuntu 14.04 – Sven Oct 02 '15 at 13:34
  • tcpdump from tcpdump.org doesn't have `-nn` - either you specify `-n`, in which case none of the conversions to names happens, no matter how many `n`s you have, or you don't specify it, in which case tcpdump tries to do all of the conversions. Perhaps the Red Hat/Fedora people hacked tcpdump to care how many times you specified `n`. –  Oct 02 '15 at 18:50