Often the most effective way of troubleshooting a networking problem is through packet capturing, also known as packet sniffing. One way of capturing packets is to use the command-line tool tcpdump, which is part of the default pfSense installation. tcpdump is a command-line utility used to capture and analyze packets; details can either be displayed on the screen or saved to a file. It uses the libpcap library for packet capturing.
The results of packet capture will differ depending on which interface's traffic you capture. As a result, you should give some consideration as to which interface's traffic you choose to capture, and in some cases, you may want to capture traffic from several interfaces at the same time. In order to use ...
