FTP Port Forwarding

nepalproxy · 10-17-2012, 03:18 AM

I have the following requirement, I am a general user and do not have much idea about it.

My FTP Server is installed on 192.168.1.200
My Public IP is 202.70.56.12

I have Centos 6.3 Installed on two machines

Centos 1 has 202.70.56.12 IP
Centos 2 has 192.168.1.200 IP

I want to forward all ftp request on Centos 1 IP 202.70.56.12 to 192.168.1.200

I tried using iptables but do not succeed..

Please help me with all detailed steps.

KatrinAlec · 10-17-2012, 04:57 AM

You'll have to use the table for nat and there are two ports envolved.

First step is a destination nat
if you try to reach your public ip on port 21 (the control-channel) forward it to your FTP Server.

You also need the state ESTABLISHED to let things back out.

Then you need the state RELATED for the data channel (port 20) so that your firewall knows to let that port through as well.

Since I don't know the syntax by heart:
http://stackoverflow.com/questions/1...nd-passive-ftp

piquezino · 10-19-2012, 11:02 AM

Hello,

Try this :

Quote:

# echo 1 > /proc/sys/net/ipv4/ip_forward

Quote:

iptables -t nat -A PREROUTING -d 192.168.1.200 -p tcp –dport 21 -j DNAT –to-dest 202.70.56.12
iptables -t nat -A POSTROUTING -d 202.70.56.12 -p tcp –dport 21 -j SNAT –to 192.168.1.200