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How can I bypass CGNAT by using a VPS with a public IPv4 address? (lemmy.zip)

submitted 6 months ago by [email protected] to c/selfhosted

53 comments fedilink hide all child comments

I want to move away from Cloudflare tunnels, so I rented a cheap VPS from Hetzner and tried to follow this guide. Unfortunately, the WireGuard setup didn't work. I'm trying to forward all traffic from the VPS to my homeserver and vice versa. Are there any other ways to solve this issue?

VPS Info:

OS: Debian 12

Architecture: ARM64 / aarch64

RAM: 4 GB

Traffic: 20 TB

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[–] [email protected] 21 points 6 months ago* (last edited 6 months ago) (20 children)

You don't want to forward all traffic. You can do SNAT port forwards across the VPN, but that requires the clients in your LAN to use the VPS as their gateway (I do this for a few services that I can't run through a proxy; its clunky but works well).

Typically, you'll want to proxy requests to your services rather than forwarding traffic.

Setup Wireguard or OpenVPN on the VPS as a server VPN. Allow whatever listener port in the firewall (I use ufw on Debian, but you can use iptables if you want)
Install HAProxy or Nginx (or Nginx Proxy Manager) on the VPS to act as your frotnend. Those will listen on ports 80/443 and proxy requests to your backend servers. They'll also be responsible for SSL termination, and your public-facing certs will be set there.
Point your DNS records for your services to the VPS's public IPv4
On your LAN, configure your router to connect to the VPS as a VPN client and route into your LAN from the VPN subnet -or- install the VPN client (WG/OVPN) on each host
In your VPS's reverse proxy (HAProxy, etc), set the backend server address and port to the VPN address of your host

I've done this since ~2013 (before CF tunnels were even a product) and has worked great.

My original use case was to setup direct connectivity between a Raspberry PI with a 3G dongle with a server a home on satellite internet. Both ends of that were behind CG-NAT, so this was the solution I came up with.

[–] [email protected] 3 points 6 months ago (1 children)

Out of curiosity, why not a simple reverse proxy on the VPS (that only adds client real IP to headers), tunneled to a full reverse proxy on the home server (that does host routing and everything else) through a SSH tunnel?

[–] [email protected] 1 points 6 months ago (1 children)

How would that kind of a setup look like?

[–] [email protected] 4 points 6 months ago* (last edited 6 months ago) (1 children)

Variant 1:

SSH tunnel established outgoing from home server to VPS_PUBLIC_IP:22, which makes an encrypted tunnel that "forwards" traffic from VPS_PUBLIC_IP:443 to HOME_LOCALHOST:443.
Full reverse proxy listening on HOME_LOCALHOST:443 and does everything (TLS termination, host routing, 3rd-party auth etc.)
Instead of running home proxy on the host you can ofc run it inside a container, just need to also run the ssh tunnel from inside that container.

Pro: very secure, VPS doesn't store any sensitive data (no TLS certificates, only a SSH public key) and the client connections pass through the VPS double-encrypted (TLS between client browser and home proxy, wrapped inside SSH).

Con: you don't get the client's IP. When the home apps receive the connections they appear to originate at the home end of the SSH tunnel, which is a private interface on the home server.

Variant 2 (in case you need client IPs):

SSH tunnel established same way as variant 1 but listens on VPS_LOCALHOST:PORT.
Simple reverse proxy on VPS_PUBLIC_IP:443. It terminates the TLS connections (decrypts them) using each domain's certificate. Adds the client IP to the HTTP headers. Forwards the connection into VPS_LOCALHOST:PORT which sends it to the home proxy.
Full reverse proxy at home set up same way as variant 1 except you can listen to 80 and not do any TLS termination because it's redundant at this point – the connection has already been decrypted and will arrive wrapped inside SSH.

Pro: by decrypting the TLS connection the simple proxy can add the client's IP to the HTTP headers, making it available to logs and apps at home.

Con: the VPS needs to store the TLS certificates for all the domains you're serving, you need to copy fresh certificates to the VPS whenever they expire, and the unencrypted connections are available on the VPS between the exit from TLS and the entry into the SSH tunnel.

Edit: Variant 3? proxy protocol

I've never tried this but apparently there's a so called proxy_protocol that can be used to attach information such as client IP to TLS connections without terminating them.

You would still need a VPS proxy and a home proxy like in variant 2, and they both need to support proxy protocol.

The frontend (VPS) proxy would forward connections in stream mode and use proxy protocol to add client info on the outside.

The backend (home) proxy would terminate TLS and do host routing etc. but also it can unpack client IP from the proxy protocol and place it in HTTP headers for apps and logs.

Pro: It's basically the best of both variant 1 and 2. TLS connections don't need to be terminated half-way, but you still get client IPs.

Please note that it's up to you to weigh the pros and cons of having the client IPs or not. In some circumstances it may actually be a feature to not log client IPs, for example If you expect you might be compelled to provide logs to someone.

[–] [email protected] 1 points 6 months ago (1 children)

Very interesting... How do I get started?

[–] [email protected] 1 points 6 months ago (1 children)

The SSH tunnel is just one command, but you may want to use autossh to restart it if it fails.

If you choose variant 2 you will need to configure a pass-through reverse proxy on the VPS that does TLS termination (uses correct certificates for each domain on 443). Look into nginx, caddy, traefik or haproxy.

For the full home proxy you will once again need a proxy but you'll additionally need to do host routing to direct each (sub)domain to the correct app. You'll probably want to use the same proxy as above to avoid learning two different proxies.

I would recommend either caddy (both) or nginx (vps) + nginx proxy manager (home) if you're a beginner.

[–] [email protected] 1 points 6 months ago (1 children)

How do I make the SSH tunnel forward traffic? It can't be as easy as just running ssh user@SERVER_IP in the terminal.

(I only need variant 1 btw)

[–] [email protected] 1 points 6 months ago* (last edited 6 months ago) (1 children)

You also add the -R parameter:

ssh -R SERVER_IP:443:HOME_PROXY_IP:HOME_PROXY_PORT user@SERVER_IP

https://linuxize.com/post/how-to-setup-ssh-tunneling/ (you want the "remote port forwarding"). ssh -R, -L and -D options are magical, more people should learn about them.

You may also need to open access to port 443 on the VPS. How you do that depends on the VPS service, check their documentation.

[–] [email protected] 1 points 6 months ago (1 children)

Hi, whenever I try to enter the ports 80 and 443 at the beginning of the -R parameter, I get this error: Warning: remote port forwarding failed for listen port 80. How do I fix this?

[–] [email protected] 1 points 6 months ago

Ah yes. Ports below 1024 are normally privileged and only superuser can use them (and the account you're using to ssh in is not and should not be root).

This link has several possible solutions: https://unix.stackexchange.com/questions/10735/allowing-a-regular-user-to-listen-to-a-port-below-1024

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[–] [email protected] 8 points 6 months ago (2 children)

I use rathole https://github.com/rapiz1/rathole
Its been solid.

[–] [email protected] 5 points 6 months ago* (last edited 6 months ago) (1 children)

I use this too, and it should be noted that this does not require wireguard or any VPN solution. Rathole can be served publicly, allowing a machine behind a NAT or firewall to connect.

[–] [email protected] 1 points 6 months ago (1 children)

I like that its really simple and obvious, with a good confif file structure.
Server forwards a port to a client.
Client forwards that to an ip:port.

If you need to know the real IP, its up to you to run reverse-proxies that support PROXY TCP headers or insert x-forward-for, or whatever.
Rathole does its thing, only its thing, and does it well.

[–] [email protected] 1 points 6 months ago

The Linux way, as it was written.

[–] [email protected] 3 points 6 months ago

This looks really interesting. I'll check it these days.

[–] [email protected] 6 points 6 months ago (1 children)

I managed this by using tailscale, with a kind of weird setup I think, but it just works.

I have tailscale on the VPS and my local server, let's say its tailscale name is potatoserver

Then with Caddy on the VPS i have something like:

mywebsite.com { reverse_proxy potatoserver:port }

And so mywebsite.com is accessible on the clearnet through the VPS

Though given you're getting rid of cloudflare tunnles I don't know if you'd want to get into Tailscale. There's Headscale too but I haven't worked with it so I can't comment

[–] [email protected] 3 points 6 months ago

I only use headscale. It just works and does not complain.

[–] MrMcGasion 3 points 6 months ago

Not sure exactly how good this would work for your use case of all traffic, but I use autossh and ssh reverse tunneling to forward a few local ports/services from my local machine to my VPS, where I can then proxy those ports in nginx or apache on the VPS. It might take a bit of extra configuration to go this route, but it's been reliable for years for me. Wireguard is probably the "newer, right way" to do what I'm doing, but personally I find using ssh tunnels a bit simpler to wrap my head around and manage.

Technically wireguard would have a touch less latency, but most of the latency will be due to the round trip distance between you and your VPS and the difference in protocols is comparatively negligible.

[–] [email protected] 3 points 6 months ago

This one works , I myself have done it cause my shitty isp needs a huge payment for a static public ip. A 5$ VPS was much cheaper . Server behind NAT I can help if you got any doubts

[–] [email protected] 2 points 6 months ago* (last edited 6 months ago)

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters	More Letters
CF	CloudFlare
CGNAT	Carrier-Grade NAT
DNS	Domain Name Service/System
HTTP	Hypertext Transfer Protocol, the Web
IP	Internet Protocol
NAT	Network Address Translation
Plex	Brand of media server package
SSH	Secure Shell for remote terminal access
SSL	Secure Sockets Layer, for transparent encryption
TCP	Transmission Control Protocol, most often over IP
TLS	Transport Layer Security, supersedes SSL
UDP	User Datagram Protocol, for real-time communications
VPN	Virtual Private Network
VPS	Virtual Private Server (opposed to shared hosting)
nginx	Popular HTTP server

[Thread #635 for this sub, first seen 27th Mar 2024, 18:15] [FAQ] [Full list] [Contact] [Source code]

[–] [email protected] 2 points 6 months ago* (last edited 6 months ago)

I had a similar problem like you. My provider only gives me a public IPv6 but no public IPv4. Im using a VPS with an IPv4 with jool to set up SIIT-DC https://nicmx.github.io/Jool/en/siit-dc.html

This converts all IPv4 traffic arriving at the VPS to IPv6 traffic which gets then directly routed to my homeserver.

Not sure if this setup would work for you. This is not a viable solution if you are completly behind a CGNAT without even a public IPv6.

Pro:

Works without any sensitive Data on the VPS (SSl certificates/passwords...)
Works for all IP based traffic (TCP,UDP,ICMP)
The original source IPv4 can be restored by the homeserver Contra:
AFAIK you cannot choose to only forward some TCP ports. Everything gets redirected.
You cannot access the VPS via IPv4 anymore since it gets redirected to your homeserver. (I only access my VPS via IPv6)
No (additional) encryption. (This is no problem for me since all my traffic is already e2e encrypted)

[–] [email protected] 2 points 6 months ago (1 children)

Do you have a working Wireguard connection? If so you can setup two reverse proxies.

[–] [email protected] 1 points 6 months ago (1 children)

Not really, pinging my homeserver via the VPS returns:

PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
From 10.0.0.1 icmp_seq=1 Destination Host Unreachable
ping: sendmsg: Destination address required
From 10.0.0.1 icmp_seq=2 Destination Host Unreachable
ping: sendmsg: Destination address required
^C
***
10.0.0.2 ping statistics
***
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 1019ms

[–] [email protected] 2 points 6 months ago (1 children)

Forget iptables. You have a broken Wireguard setup. Did you verify that you have the proper keys and that Wireguard is allowed though the firewall?

[–] [email protected] 1 points 6 months ago (2 children)

I have no idea how to properly manage the firewall with Hetzner. I've opened the ports on the Hetzner management page and I ran several iptables commands to allow traffic from those ports. Still doesn't work. This is weird!

[–] [email protected] 1 points 6 months ago (1 children)

What firewall are you using in the VPS? It will likely be firewalld or ufw

[–] [email protected] 1 points 6 months ago (1 children)

Does iptables count as a firewall? You said that I should "forget" iptables. Is it that bad? It came preinstalled on the VPS. Should I switch? And if so, how?

[–] [email protected] 1 points 6 months ago (1 children)

Iptables is the low level mechanism that handles network routing. Firewall software just takes it up a layer so you can manage it without crazy long commands

[–] [email protected] 1 points 6 months ago* (last edited 6 months ago) (1 children)

Alright, sounds good. What firewall are you recommending me to use? I would like to use a firewall that's easy to manage.

Edit: I went with ufw.

[–] [email protected] 1 points 6 months ago

Sorry I didn't mean you should go out and create a firewall. (Although that's a good idea) I mean there is a issue with either your connectivity or your Wireguard config.

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[–] [email protected] 1 points 6 months ago

Here https://wiki.gardiol.org/doku.php?id=router:ssh_tunnel

[–] kokesh 1 points 6 months ago* (last edited 6 months ago)

I did this. Works flawlessly for half year now. I have x86 thin client at home running all my stuff, it creates tunnel to my VPS (I use Free tier Oracle VPS - yes, it is a shit company, I know, no need to let me know again in the comments). Works like a charm. This GitHub repo has automated installer for Oracle, Amazon,... https://github.com/mochman/Bypass_CGNAT/wiki/Oracle-Cloud-(Automatic-Installer-Script) - it installs and configures Wireguard on both server (VPS) and client (your home machine).

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