Pcap recipes
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tcpdump
Ring-buffer capture
This example captures continuously from interface 'eth0', writing up to '-C 1'x1MB into '-w somehost.capN', keeping a maximum of '-W 10' files, overwriting the oldest when the limit is hit.
$ sudo tcpdump -nn -i eth0 -C 1 -W 10 -w somehost.cap host 10.5.10.20 & ... $ ls -alF total 2104K drwxrwxr-x 3 jontow jontow 4096 Apr 6 11:33 ./ drwxrwxr-x 5 jontow jontow 4096 Apr 6 10:16 ../ -rw-r--r-- 1 root root 1000065 Apr 6 11:20 somehost.cap0 -rw-r--r-- 1 root root 1000079 Apr 6 11:33 somehost.cap1 -rw-r--r-- 1 root root 131072 Apr 6 11:36 somehost.cap2 ...