Forward port to local ip + port

Question

On my Ubuntu 14.04 I have a service running on a local IP (192.168.33.99) and port 80. In my network, my Ubuntu computer has IP 192.168.2.3. Now I want to redirect all traffic on 192.168.2.3:8080 to 192.168.33.99:80 (note that this is a local IP on the Ubuntu machine). How can I do that?

Solution

What you're looking for is called NAT.

First we want to enable portforwarding:

sysctl net.ipv4.ip_forward=1

Now we should add a rule that forwards all incoming traffic on 8080:

iptables -t nat -A PREROUTING -p tcp --dport 8080 -j DNAT --to-destination 192.168.33.99:80

Then all that is left, is iptables to masquerade

iptables -t nat -A POSTROUTING -j MASQUERADE

What is masquerade?

Comments

[www.data-blogger.com]

Thank you! I now get the following message after trying to reach 192.168.2.3:8080 -> ERR_CONNECTION_REFUSED. How can I resolve this?

[rowan]

@Kevin - are you able to reach 192.168.33.99:80? Also please post output of iptables -nvL

[www.data-blogger.com]

Yes @FAT32, but I am not able to reach the 192.168.2.3:8080

[rowan]

@Kevin - Please post output of iptables -nvL

[www.data-blogger.com]

Ah, it is working (I can reach it through the network) @FAT32, but not on my local machine, thank you!

[rowan]

@Kevin - haha, that makes sense! Cheers =) (I was actually stressing out that I made a mistake, been a while since I did this haha)

[toing_toing]

this wonderful answer would only be more complete if you could add how to edit or change a route :)