TCPdump

Basic capture

Typical usage to capture network traffic going to a specific host:

sudo tcpdump host xxx.xxx.xxx.xxx -w output.pcap

TLS capture

In case the traffic is encrypted using TLS or similar, you may be able to use the SSLKEYLOGFILE environment variable when running your client (or server) binary:

SSLKEYLOGFILE=sslkeylogfile.log ./testapplication.py

If this produces a sslkeylogfile.log file, you can use that to decrypt the TLS traffic. Open wireshark and go to Edit - Preferences - Protocol - TLS - (Pre)-Master-Secret log filename and specify your sslkeylogfile.log file. Then open your package dump and it will be decrypted.