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I have a system running RedHat and would like to know if any rules can be set in IPChains, so that it can expicitly allow tcp 110.
The reason is that, I have enabled Pop3 services to run on the machine, but users are not able to receive email when they are popping the mail..They can however send the mail...
What version of Redhat are you using? Ipchains is fairly old and has been deprecated in favor of Iptables. The rule should be very similar, but the syntax is slighly differnet depending on whether you are using ipchains or iptables.
Redhat Linux Enerprise Edition ES 2.1 should be using the 2.4.x series kernel and should therefore have support for iptables. You might want to think about using the iptables facility which allows for statefull packet filtering. If you don't care to switch, this rule should work for ipchains:
Just enter them in from the command line just like you would with any other command, though you will have to be root. If the command has been entered properly, you should just get a new bash prompt, otherwise you should see an error message. Then to save the rules (otherwise they would be lost on reboot), do:
That should definitely work. Also keep in mind that if you enter the syntax improperly, then nothing is loaded to the ruleset (you can confirm that with ipchains -L) If you need to stop, start, or restart the ipchains facility. just do: