Selfhosted

37814 readers

492 users here now

A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.

Rules:

Be civil: we're here to support and learn from one another. Insults won't be tolerated. Flame wars are frowned upon.
No spam posting.
Posts have to be centered around self-hosting. There are other communities for discussing hardware or home computing. If it's not obvious why your post topic revolves around selfhosting, please include details to make it clear.
Don't duplicate the full text of your blog or github here. Just post the link for folks to click.
Submission headline should match the article title (don’t cherry-pick information from the title to fit your agenda).
No trolling.

Resources:

Any issues on the community? Report it using the report flag.

Questions? DM the mods!

founded 1 year ago

MODERATORS

Unable to forward ports using wireguard (lemmy.sdf.org)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/selfhosted

18 comments fedilink hide all child comments

Update: Sorry guys, looks like I just needed to reboot the public server.

My goal is to forward port 8096 from my private server to my public server. That, is any traffic at public server's port 8096 should be tunneled to port 8096 of my private server and back.

I've set up a wireguard tunnel and ping is working from one device to the other. In this, 10.8.0.1 is the private server and 10.8.0.2 is the public server.

Here are my config files (/etc/wireguard/wg0).

***
On the public server
***
[Interface]
Address = 10.8.0.2/24
ListenPort = 51820
PrivateKey = *****************************************

# packet forwarding
PreUp = sysctl -w net.ipv4.ip_forward=1

# port forwarding
PreUp = firewall-cmd --zone=public --add-port 8096/tcp
PreUp = iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 8096 -j DNAT --to-destination 10.8.0.1:8096
PostDown = iptables -t nat -D PREROUTING -i eth0 -p tcp --dport 8096 -j DNAT --to-destination 10.8.0.1:8096
PostDown = firewall-cmd --zone=public --remove-port 8096/tcp

# packet masquerading
PreUp = iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADE
PostDown = iptables -t nat -D POSTROUTING -o wg0 -j MASQUERADE

[Peer]
PublicKey = *****************************************
AllowedIPs = 10.8.0.1

***
On the private server
***
[Interface]
Address = 10.8.0.1/24
PrivateKey = *****************************************

[Peer]
PublicKey = *****************************************
AllowedIPs = 10.8.0.2
Endpoint = <public-server-addr>:51820
PersistentKeepalive = 25

Now, I'm trying to test the connection using netcat. I'm listening from my private server using nc -l 8096 (I've made sure that the port is unblocked) and trying to connect from a third device using nc <public-server-addr> 8096 but it's not working.

I have no idea what's going on here. Some help from experienced people is very appreciated.

you are viewing a single comment's thread
view the rest of the comments

[–] [email protected] 2 points 1 year ago (1 children)

You have to have a firewall rule on your public server to tell it to send any traffic on port 8096 to the IP of your private server. Currently, your public server isn't listening on that port, so the packets would just be dropped.

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (2 children)

Don't PreUp = iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 8096 -j DNAT --to-destination 10.8.0.1:8096 and PreUp = iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADE do that?

I'm new to this stuff, so I'm probably wrong. What do you think I need to do to achieve this?

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago)

It should yeah, that's the whole point of doing that through firewall. I'm not entirely sure how MASQUERADE will interact with a prior DNAT though.

[–] [email protected] 2 points 1 year ago (1 children)

Ah, I did the bad thing and didn't read properly.

It looks correct, yes. Can you run iptables -L -t nat on the public host after bringing up the wireguard connection to see if it works?

Also, if you can do a netcat to that same port from a local computer to that public endpoint without the wireguard connection running, you can test that the port isn't being blocked anywhere else along the way.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago)

Edit: Looks like I just needed to reboot the public server.

This is what I get when I do it.

Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination
DOCKER     all  --  anywhere             anywhere             ADDRTYPE match dst-type LOCAL
DNAT       tcp  --  anywhere             anywhere             tcp dpt:8096 to:10.8.0.1:8096
DNAT       tcp  --  anywhere             anywhere             tcp dpt:8096 to:10.8.0.1:8096

Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
DOCKER     all  --  anywhere            !localhost/8          ADDRTYPE match dst-type LOCAL

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination

And yes, it's working locally. I even got it to work through the tunnel using redir but I need the masquerading to hide my private server's IP.

I saw a difference when it worked. I got server [192.168.0.5] 8096 open on connection. But I didn't see it through this setup. I simply don't get any reply at all.