Debugging HTTP On Server With tcpdump¶
So you have a connectivity problem and for whatever reason (firewalls, urgency) you need to debug this on a remote server.
This is a command line tool very much like Wireshark, with it you can see activity.
Here is a great blog post that gives a load of examples:
Debugging Connections with A Particular Host¶
If you need to figure out what is going on when the server tries to communicate with a particular host, try this:
tcpdump -i any host 220.127.116.11 -vvv