iptables

Created 2022-06-12

Redirect port 300 to port 3000.:

sudo iptables -t nat -I PREROUTING --src 0/0 --dst 127.0.0.1 -p tcp --dport 300 -j REDIRECT --to-ports 3000
sudo iptables -t nat -I OUTPUT --src 0/0 --dst 127.0.0.1 -p tcp --dport 300 -j REDIRECT --to-ports 3000

It might have some snags, though.

The above won't survive reboot.