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Old 02-01-2017, 01:35 AM   #1
luofeiyu
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What is the difference between -n and -nn in tcpdump?


Man tcpdump:
-n Don't convert addresses (i.e., host addresses, port numbers,
etc.) to names.

sudo tcpdump -i eth0 -nn 'host 192.168.1.176'
sudo tcpdump -i eth0 -n 'host 192.168.1.176'
 
Old 02-01-2017, 03:28 AM   #2
TenTenths
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Distribution: Centos 5 / 6 / 7
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As you give no useful information whatsoever, such as distro, version of tcpdump, etc. here's what I just read off my screen:

Code:
man tcpdump
       -n     Don’t convert host addresses to names.  This can be used to avoid DNS lookups.

       -nn    Don’t convert protocol and port numbers etc. to names either.
CentOS release 6.8 (Final)

# tcpdump -V
tcpdump version 4.1-PRE-CVS_2016_05_10
libpcap version 1.4.0

Last edited by TenTenths; 02-01-2017 at 03:29 AM.
 
2 members found this post helpful.
Old 02-01-2017, 07:46 AM   #3
luofeiyu
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My os is debian8.
 
  


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