How to forward port 80 to another port on the samemachine?

Question

How can I forward requests coming in on port 80 to another port on the same linux machine?

I used to do this by changing nat.conf, but this machine that I'm using doesn't have NAT. What's the alternative?

No NAT whatsoever or just no nat.conf? Have you tried any iptables rules using NAT? — Ben Swinburne, Oct 11 '11 at 22:38

score 58 · Answer 1 · edited Apr 13 '19 at 12:00

58

You can accomplish the redirection with iptables:

iptables -A INPUT -i eth0 -p tcp --dport 80 -j ACCEPT

iptables -A INPUT -i eth0 -p tcp --dport 8080 -j ACCEPT

iptables -A PREROUTING -t nat -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 8080

edited Apr 13 '19 at 12:00

Eddie C.

547

answered Oct 11 '11 at 23:34

Thomas Vincent

1,110

+1. Being doing this for years – Alexander Pogrebnyak Oct 12 '11 at 00:33
1

How about on Windows Server? – Luc Aug 26 '12 at 21:26
Oh man this is exactly what I was looking for, kudos! – neurosnap May 07 '15 at 18:13
Didn't work for me at first, but was fine when I used sudo – mdiscenza Sep 06 '16 at 17:58
1

what to do if no eth0 interface? why not use loopback interface? – harschware Jul 04 '18 at 14:04
Third one did the trick for me as always. – David J Eddy Apr 23 '19 at 00:40

score 25 · Answer 2 · edited Jul 06 '20 at 05:53

25

Just found myself in this question and couldn't find an easy way. Don't want to install Nginx in my machine to do this simple port forwarding.

Rinetd didn't work for me, no working package for my distro. I went for socat instead. Super simple:

socat TCP-LISTEN:80,fork TCP:127.0.0.1:5000

Must be ran as root to be able to listen on port 80.

edited Jul 06 '20 at 05:53

Tansc

3

answered Feb 03 '16 at 20:36

alfetopito

351

Rinetd setup is easier I think. – johnshen64 Oct 12 '11 at 04:11
1

socat works perfectly! – viv Jun 06 '19 at 12:43
I don't know how to make socat close the socket when interrupted with ctrl+C, so this solution used verbatim will fail for some time after socat is ctrl+C interrupted, but as a quick hack it's possible to add reuseaddr to it to avoid this error. Also use port 443 instead of 80 to forward HTTPS – user202729 Dec 22 '22 at 08:55

score 11 · Answer 3 · edited Apr 13 '19 at 12:00

11

You should look at using a reverse proxy, such as Nginx. For example, you might put something like this in your nginx.conf file:

server {
    listen         80;

    server_name    your_ip_address your_server_name

    access_log   /var/log/nginx/your_domain/access.log ;
    error_log    /var/log/nginx/your_domain/error.log info ;

    location / {
        proxy_pass  http://127.0.0.1:3000;   # pass requests to the destination
    }
}

edited Apr 13 '19 at 12:00

Eddie C.

547

answered Oct 11 '11 at 22:42

Tilo

391
1
5

4

Why? I don't neccessarily disagree but is there a good reason you wouldn't want this to just happen™ in the networking stack? – Oli Aug 19 '16 at 13:13
1

@Oli This reverse proxy method will not affect numerous other virtual hosts on the server, which would occur if iptables would do it since iptables knows nothing of virtual hosts. – Ash Oct 14 '17 at 22:48

How to forward port 80 to another port on the samemachine?

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