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I'm using my server as NAT/router, which works well. But now I'm trying to forward port 3478, which I can't get to work.

eth0 = public interface
eth1 = private network

$ cat /proc/sys/net/ipv4/conf/eth0/forwarding
1
$ cat /proc/sys/net/ipv4/conf/eth1/forwarding
1

Then to forward port 3478 to 10.0.0.7, I read somewhere that I should run

iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 3478 -j DNAT --to-destination 10.0.0.7:3478
iptables -A FORWARD -p tcp -d 10.0.0.7 --dport 3478 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

I also ran

ufw allow 3478

But testing port 3478 with http://www.canyouseeme.org/ doesn't work. Any idea what I have done wrong?

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Here's a few methods of port forwarding serverfault.com/questions/401842/… –  Sonassi Sep 22 '12 at 13:55
    
Does the machine 10.0.0.7 also have a proper Netfilter MASQUERADING or SNAT rule? –  Alexander Janssen Oct 8 '12 at 17:51
    
@AlexanderJanssen No idea, it's a Win 7 box –  Znarkus Oct 9 '12 at 8:35
    
@Znarkus in mean in your Ubuntu firewall. Check the OUTPUT chain of the NAT table. –  Alexander Janssen Oct 9 '12 at 8:40
    
@AlexanderJanssen iptables -L OUTPUT -t nat looks empty. –  Znarkus Oct 9 '12 at 12:40

1 Answer 1

I use port forwarding (and working) on Ubuntu server with:

#NAT:
-A PREROUTING -i eth0 -p tcp --dport 3478 -j DNAT --to 10.0.0.7

#FORWARD:
-A FORWARD -p tcp -i eth0 -d 10.0.0.7 --dport 3478 -j ACCEPT
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