[SOLVED] What is the difference between -n and -nn in tcpdump?

luofeiyu · 02-01-2017, 01:35 AM

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'

TenTenths · 02-01-2017, 03:28 AM

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

luofeiyu · 02-01-2017, 07:46 AM

My os is debian8.