freeciv in lsof output

I'm working an issue with [ZeroMQ](https://zeromq.org/) using [XSub-XPub](https://netmq.readthedocs.io/en/latest/xpub-xsub/) . I did lsof on bind in port and see:

lsof -i :5556
COMMAND    PID      USER   FD   TYPE  DEVICE SIZE/OFF NODE NAME
python  475590 codespace   45u  IPv4 1432077      0t0  TCP localhost:51620->localhost:freeciv (ESTABLISHED)
python  475684 codespace   12u  IPv4 1421144      0t0  TCP *:freeciv (LISTEN)
python  475684 codespace   15u  IPv4 1430650      0t0  TCP localhost:freeciv->localhost:51620 (ESTABLISHED)

What is freeciv? Search only yields [a video game](https://freeciv.org/) , but it's not that. Ubuntu 20.04.6.