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.
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I suspect the mixing of firewalld and iptables might not be helping there.
Other than that,
-j REDIRECTmight be a bit easier than DNAT, because with DNAT you also need to deal with SNAT too otherwise stuff won’t come back to the client properly.Best way to troubleshoot this would be to tcpdump on both ends, and see if packets are coming in, and if they’re also coming out.
Edit: Looks like I just needed to reboot the public server.
I was able to get it to work using
redirbut I do need masquerading.
It’s been a long time since I did forwarding through wireguard so this might be outdated, missing info or actually doing unneeded stuff but I had this notes saved in some old iptables personal documentation from like 4 years ago that might shed you some light:
Allow first packet to start the connection
iptables -A FORWARD -i eth0 -o wg0 -p tcp --syn --dport 80 -m conntrack --ctstate NEW -j ACCEPT iptables -A FORWARD -i eth0 -o wg0 -p tcp --syn --dport 443 -m conntrack --ctstate NEW -j ACCEPTAllow already established connections
iptables -A FORWARD -i eth0 -o wg0 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT iptables -A FORWARD -i wg0 -o eth0 -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPTSend whatever arrives via port 80 or 443 to the other side of the wg tunnel
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination 192.168.3.1 iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j DNAT --to-destination 192.168.3.1Modify source address so it can return
iptables -t nat -A POSTROUTING -o wg0 -p tcp --dport 80 -d 192.168.3.1 -j SNAT --to-source 192.168.3.2 iptables -t nat -A POSTROUTING -o wg0 -p tcp --dport 443 -d 192.168.3.1 -j SNAT --to-source 192.168.3.2@eskuero @SexualPolytope do you have the nftables version?
If I run
iptablesdirectly, it tells me that I have thenf_tablesversion.@SexualPolytope yeah. It’s rare that nftables isn’t the default anymore.
Thanks. I’ll try these out.
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.
Don’t
PreUp = iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 8096 -j DNAT --to-destination 10.8.0.1:8096andPreUp = iptables -t nat -A POSTROUTING -o wg0 -j MASQUERADEdo that?I’m new to this stuff, so I’m probably wrong. What do you think I need to do to achieve this?
Ah, I did the bad thing and didn’t read properly.
It looks correct, yes. Can you run
iptables -L -t naton 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.
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 destinationAnd yes, it’s working locally. I even got it to work through the tunnel using
redirbut 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 openon connection. But I didn’t see it through this setup. I simply don’t get any reply at all.
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.
