Simple configuration with mail server with 993 imap port.Local IP is static natted at main router to public IP.I need to restrict access to 993 port by local lan and allow connection to imapl port by special myknown ports.Understand that source IP connecting to special ports are public.So I wonder can it be performed by local iptables or do I need to route special ports by other local host? What did I miss?iptables -A INPUT -p tcp --dport 33333 -j ACCEPTiptables -A INPUT -p tcp --dport 33334 -j ACCEPTiptables -A INPUT -p tcp -s 192.168.0.0/24 --dport 993  -j ACCEPTiptables -A PREROUTING -t nat -p tcp --dport 33333 -j REDIRECT  --to-port 993iptables -A PREROUTING -t nat -p tcp --dport 33334 -j REDIRECT  --to-port 993Update:I need to open ports 33333 and 33334 for internet and local lan and keep opened 993 port for local lan only.33333 and 33334 ports are forwarded to 993.Forwarding doesn't work in case 993 restricted: -s 192.168.0.0/24.Server has one ethernet interface.
How to restrict main port by iptables and allow service at other port
iptables;port forwarding