Trace Connection (TRCCNN) is used to find out information through a network address (IP or domain).
Here is an example of using Trace Connection on the AS400:

TRCCNN SET(ON) TRCTYPE(IP) TRCTBL(TRCCNN) SIZE(500 MB) TCPDTA(TCP () () *N ‘n.n.n.n’)
…change n.n.n.n with the TCP / IP address (if what we want to trace is the IP) of the remote system that we want. In the TCP / IP data section, enter the specific IP and port you want (local or remote).

The above command is only to turn on Trace Connection, to turn it off you can use the command:

TRCCNN SET(OFF) TRCTBL(TRCCNN) OUTPUT(STMF) TOSTMF(‘/tmp/AnyFileName.pcap’ *YES)
… Replace /tmp/AnyFileName.pcap with the desired IFS path and with a .pcap file format.

To read the results of the trace connection, we can use 3rd party applications such as Wireshark and others.

For more details, see the following IBM web: