Can't forward port to internal linux box

NetAX · 03-26-2006, 04:38 PM

I have a test environment where I have one linux box acting as the NAT box. From the NAT box I am able to access port 222 (The "internal" linux box) with no problem.

If I try to access port 222 via the "WAN" IP address of the NAT box I cannot get through.

NAT box:
eth0 10.0.0.3 (connected to internal machine network)
eth1 172.17.64.202 ("WAN" IP address)

Internal box:
eth1 10.0.0.1

I have tried using the following commands which do not work for me:

Code:

iptables -t nat -A PREROUTING -p TCP -i eth1 -d 172.17.64.202 --dport 222 -j DNAT --to-destination 10.0.0.1:222

Code:

iptables -A POSTROUTING -t nat -o eth1 -j MASQUERADE

This command reports 1

Code:

cat /proc/sys/net/ipv4/ip_forward

I am using SuSE 10 and have the firewall shut off for now. Can anybody tell me what I'm doing wrong?

RobertP · 03-26-2006, 06:50 PM

iptables -L

might show something unexpected. Also, check logs and give any warnings or error messages from iptables.

NetAX · 03-26-2006, 07:20 PM

I figure it out. I used the wrong interface for POSTROUTING.

Code:

iptables -A POSTROUTING -t nat -o eth0 -j MASQUERADE