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networkingftpportforwardingipsec

Forwarding FTP port on IP-SEC server to another FTP server

Please execuse my shallow networking knowledge.

I have the current setup (IP-sec server) tunnelled to (External FTP server), I need to connect to the (External FTP server) through the (IP-sec server) using FTP CLI from any client. My question is is there a way to forward the request from the (IP-sec server) to (External FTP server) directly without having to use FTP CLI on the (IP-sec server) itself.

I tried iptables -t nat -A PREROUTING -p tcp -m tcp --dport 21 -j DNAT --to-destination (External FTP server):21 on the (IP-sec server) but that did not work.

Solution

  • You need to do also nat postrouting to source nat the traffic so that it returns back to the same box you are doing the prerouting on.

    iptables -t nat -A POSTROUTING -p tcp -m tcp --dport 21 -d (externalFTPserverIP) -j SNAT ip-address-you-want-traffic-to-return-to