this is obsolete doc -- see http://doc.nethence.com/ instead

Common notes for GNU/Linux systems 

Enable a user to use tcpdump, 

  groupadd pcap 

  usermod -a -G pcap user 

  ls -l /usr/bin/tcpdump 

  setcap cap_net_admin+ep /usr/bin/tcpdump 

Refs. 

http://peternixon.net/news/2012/01/28/configure-tcpdump-work-non-root-user-opensuse-using-file-system-capabilities/ 

http://askubuntu.com/questions/530920/tcpdump-permissions-problem