As @jtgrassie already mentioned,
ufw is one of the tools that allows you to manage your ports.
It is convenient to use
ufw in a script, in conjunction with a cronjob, that automates the opening and closing of the port. I find such script particularly useful when I may want to temporarily stop my
monerod for the sake of freeing my computer's resources (CPU/RAM/bandwith). And so the following script opens and closes port 18080 for you.
/usr/bin/pgrep -f /home/jerzy/monero-x86_64-linux-gnu-v0.17.2.0/monerod
#The following ifs deal with monerod when it is running.
if [[ "$?" == 0 ]]; then
/usr/sbin/ufw allow 18080 && /usr/sbin/ufw reload
/usr/sbin/ufw deny 18080 && /usr/sbin/ufw reload
Please remember to replace
/home/jerzy/monero-x86_64-linux-gnu-v0.17.2.0/ with the path to
monerod on your computer.
Once you've made your script executable with
sudo chmod 755 name_of_the_script.sh than proceed to schedule its execution by cron:
sudo crontab -e and appending the following line:
* * * * * /path_to_the_script.sh