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I have an RHEL 6 system which has 20 users. I have 20 ports on which separate versions of a service is running. I want user a to access port a, but not other ports. Is there a way to do this? (possibly by modifying iptables)?

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up vote 6 down vote accepted

You can use the "owner" iptables module to do this. As an example to restrict port 999 to the user 'fred' only you can use:

iptables -I OUTPUT -p tcp --dport 999 -j REJECT
iptables -I OUTPUT -p tcp --dport 999 -m owner --uid-owner fred -j ACCEPT

The above rules are inserted to the top of the OUTPUT chain so the order reject then accept.

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