i am having a problem with getting my iptables to work reliably. i have redhat 8 running as a gateway to the internet. the rest of my network is windows based. i am on dialup so i don't want to set up my own mailserver. The problem i am running into, is when i setup my iptables, then my workstations can get out to get their email. but after a few hours, it is like the iptables is closed up again. (and yes i did "service iptables save" after i set them up and they were working like i wanted.) What could this be?

thanks from a linux newbie

You may have a cron job that is running a firewall setup script every so often.