Application with Output similar to the GUI output of "WireShark"

Sure, tshark (text shark) is the same program, but with a noninteractive command line interface.

You can also run tshark on the server and transfer the captures over ssh to a wireshark gui running somewhere else.

For example:

  mbp@joy% sudo tshark -i wlan0 -p  -R 'http'
  Capturing on wlan0
  3.929359 192.168.178.22 -> 66.102.11.104 HTTP GET / HTTP/1.1 
  4.104763 66.102.11.104 -> 192.168.178.22 HTTP HTTP/1.1 301 Moved Permanently  (text/html)
  4.118925 192.168.178.22 -> 66.102.11.104 HTTP GET / HTTP/1.1 
  4.295749 66.102.11.104 -> 192.168.178.22 HTTP HTTP/1.1 302 Found  (text/html)
  4.355713 192.168.178.22 -> 66.102.11.104 HTTP GET / HTTP/1.1 
  4.560568 66.102.11.104 -> 192.168.178.22 HTTP HTTP/1.1 200 OK  (text/html)
  4.588767 192.168.178.22 -> 66.102.11.104 HTTP GET /images/nav_logo40.png HTTP/1.1 

You can also do tshark ... |tee packetlog so it goes both to the screen and to the file.

Or, alternatively, tshark -w stuff.pcap will write the raw packets into that file, which you can then copy to another machine and open within the wireshark gui, if you want to do more in-depth investigation.

tshark is a good option.

An alternative is tcpdump , which is a well-known predecessor. It's widely available on other platforms, so you might run into it even if you don't use it on your server.