A big thing the other comments are missing is that just running the iptables rule only works for the current boot. You need something to rerun it every restart
ufw is a front end to make it easier to use them
If you want/need more control, you should look into /etc/iptables/rules.d config files
Edit: or depending on what your distro already has, the firewalld comment makes a lot of sense. E.g. that’s Fedora’s default front end