ELI5 Cloudflare Tunnel

So everyone is talking about cloudflare tunnels and I decided to give it a shot.

However, I find the learning curve quite hard and would really appreciate a short introduction into how they work and how do I set them up…

In my current infrastructure I am running a reverse proxy with SSL and Authentik, but nothing is exposed outside. I access my network via a VPN but would like to try out and consider CF. Might be easier for the family.

How does authentication work? Is it really a secure way to expose internal services?

Thanks!

scaredofplanes,

Essentially it IS a tunnel, just with cloudflare’s infrastructure in the middle handling auth and obscuring each end from the other.

Auth is handled by cloudflare. That doesn’t mean cloudflare necessarily is the auth provider, though. Not likely in selfhosted, but one could set up some other auth provider, like azure, and cloudflare could give tunnel access to authorized users who actually provided credentials via azure.

The service, port, whatever being accessed via the tunnel may also require auth, and cloudflare generally doesn’t handle that. For example, your cloudflare tunnel to your local sonarr instance requires auth at cloudflare first, to access the tunnel, then again at sonarr because your sonarr instance requires authentication.

In a docker environment, you would either tunnel to the docker host or to individual Dockers. The latter is more sensible and generally a bit more secure, if only because least access = better. There’s probably some cloudflare tunnels docker out there that does half the setup for you, then you just stick it and the Dockers you want exposed through the tunnel all on the same docker network interface (which you create), but that’s just speculation.

As far as setting tunnels up goes, the docs are really good at the step by step. Easiest way to learn it is to set up a VM similar to what you want and bang away at the steps until it does what you want. Some things are easy, like RDP. Other things are trickier.

The basics of setup are that you use the cloudflared application at both ends: one server-side to expose what you want and one client-side to access the tunnel via cloudflare.

Tailscale is the same kinda thing. I think it is way easier for a lot of people. There’s a lot less setup involved. Just install the apps and make a few choices.

For personal use, I use wireguard to access my home server. Professionally I use cloudflare tunnels for a couple of things, but mostly an enterprise vpn.

operator,
operator avatar

Thank you for the detailed explanation. I am running Tailscale as a temporary solution to access some services, but I dislike that you have to set firewall rules basically twice (once in your local network and once in Tailscale). I suppose it would be similar for CF?

scaredofplanes,

Yeah, any solution is going to require at least egress rules for its traffic. Tailscale is a bit different since part of what it’s able to do is provide access to your LAN, if desired. Cloudflare just needs two ports, but it’s only providing a tunnel from the host.

spark947,

People are saying that it is a cloud managed reverse proxy, but I would not recommend using it like this. You should be running a reverse proxy on your own hardware, imo.

It is still useful because you can use it as just a proxy. You can point your dns to your cloudflare tunnel endpoint and cloudflare will screen all traffic going to your server. I’ve actually stopped using it, but it is a decent way to auto feel all the random internet traffic pitfalls like portscanning bonnets. Also putting something between your server IP and your domain is nice.

Dumbkid,
@Dumbkid@lemmy.dbzer0.com avatar

Basically just an easier way to get a tunnel into your server, instead of having to configure a reverse proxy or manage certs. I just have the cloud flared docker installed, then on their site under the tunnels section I just assign whatever domains or subdomains to all my services via a local ip address. Im doing a couple things that definitely break TOS lol. But imma let it ride till they stop me then I guess I’ll switch to a reverse proxy

CodaBool, (edited )

I used one to reach my qbittorrent selfhost. I found a cool docker image. It bundles a openVPN connection with qbittorrent so that I don’t need my home server to be on a VPN at all times. As well as ensures traffic always goes through VPN. I was running into an issue where I could not reach from my home network. But when I used a cloudflare tunnel it somehow worked. This was all until I realized there was an environment variable of LAN I needed to set which allowed connections from my home network 😮‍💨

I would definitely recommend this setup for any torrenting. I’ve been using it for years with zero IP leaks. Believe me, Spectrum would let me know. They did before I had setup.

EDIT: just realized the guy deleted the docker image for that based on a false positive (that’s been a false positive for a year). I reuploaded their same image to my docker account. Still works without any leak, not sure why they took such a drastic measure.

operator,
operator avatar

What I'm doing is using a dedicated VPN Gateway container. The instances running delicate services have a static default route to the GW-container.

This is an extra step, but allows me add easily route other services or clients or even whole networks through my VPN without additional setup or specialized containers bundling both.

Wanna use it on the phone? Change the gateway address. Wanna use it from my Linux machine? Add a static default route. Etc...

Works flawlessly!

CodaBool,

That sounds better since it doesn’t have any kind of bundling of images. Do you have a link to anything public I can look at to try out a similar setup?

operator,
operator avatar

Unfortunately not at the moment, as all is kinda fiddled and setup manually, but I’m redoing my home lab in a couple of weeks. Send me a message and I’ll send you the docker image or script!

But basically I did the following:

  • enable ipv4 forwarding
  • configure and start VPN tunnel
  • set the default route to the tunnel
  • set the gw for reaching the remote vpn server to the local gw
  • sets routes for the local network to the local gw

If your vpn goes down, the default route shall still point to the remote gw, but as it isn’t there you also have a kill switch. Voila!

I am looking into gluetun but haven’t tried it yet.

Edit: this doesn’t protect you from someone snooping the traffic inside your local net, but protects it starting from the point where it leaves the local vpngw. The traffic is unencrypted between that and your client.

pz303,

@operator

Cloudflared tunnels are great. No firewall ports to open.

I installed the Cloudflared docker, which is headless, and fed it my API key. Then Cloudflared creates a VPN between your system and theirs. Then, think of Cloudflare as the reverse proxy, you just configure it on the CF site instead of locally. No need for a reverse proxy on your side.

I've not done anything with auth on it as what I run I don't mind being public. If you still want to run a local auth, you can set it to hit your local reverse proxy instead and do it that way.

The benefits are you don't need to open firewall ports and your local IP is irrelevant so no need for dynamic DNS.

EncryptKeeper,

Just a side note that “not opening firewall ports” is not inherently a security benefit if you’re exposing the same service on the same port on the same host anyway via your reverse proxy setup.

If you were to measure your level of “security” on having ports open or not alone, then using Cloudflare tunnels could be considered worse, since an outbound VPN connection to Cloudflare is essentially circumventing your firewall’s protection entirely, meaning you’re effectively opening all 65,535 TCP and UDP ports instead of one, albeit only to Cloudflare.

There are benefits to using Cloudflare tunnels but “not opening firewall ports” is not one of them. And you could just as easily accomplish the same thing without Cloudflare by using a VPS and Tailscale with the selfhosted Headscale coordinator.

pz303,

Meh, it's sorta 6 of one and half-dozen of another. The benefit of not opening ports on a firewall isn't necessarily a security one so much of a convenience one for people who don't know how their routers work or no access to open those ports. The only security value is it prevents any exploits on your router and a port scan against your network won't show those ports open. That makes it easier to hide the fact that your hosting something. I'd agree, it's not a huge security vector to worry about, but can help people not see your real IP which has tangible value.

Really, your offloading security to CF and putting trust in them to do a better job than you, but as you said, in doing so they can sort of get the keys to your kingdom. I think it's just worth it with their other tools to block bots and other common exploits that a Netgear home router isn't looking for.

The problem with a vps and tailscale is its one more thing to manage and a vps costs money and cf is free.

rarkgrames,
@rarkgrames@lemmy.world avatar

I know some people dislike NetworkChuck but this video should help you get things going.

youtu.be/ey4u7OUAF3c

innercitadel,

I don’t get the hate.

rarkgrames,
@rarkgrames@lemmy.world avatar

No I don’t. I get he isn’t to everyone’s taste but his videos I think are enjoyable because he obviously has enthusiasm and I e set up a home lab running proxmox, a load balancer, monitoring software and a heap of other stuff because of him.

operator,
operator avatar

NetworkChuck does videos for beginners, but sometimes that’s just what an experienced user need ^^ thanks for sharing! Watching the video right now

lchapman,

Here’s how I do it: blog.lchapman.dev/self-hosting-foundations/

Note: blog isn’t monetised, I just write things up to make them easier to share with people.

Basically, I use a cloud VM as a gateway and reverse proxy to my services which are accessible via VPN. It’s not free, but it’s pretty cheap.

I have a friend who is using Cloudflare for this. He has a domain and he can access his services at domain.tld:port. Not bad, and it’s free. He could have his tunnel pointed at Caddy like I do and use subdomains, but he hasn’t got that far yet.

I prefer my method but both seem to get the basic functionality working.

operator,
operator avatar

Thanks for the write up! I’ll definately check out your blog as well. A cloud gateway is something I’ve considered as well (especially when the costs are around $5 monthly). How do you handle authentication?

lchapman,

Currently I don’t have an auth service sitting in front of my other services, it’s just whatever auth is built into each app and saved passwords.

That said, I’ve deployed Authentik at a workplace and really enjoyed working with it, using it for SSO for a variety of services. I’ll implement it on my own platform soon.

ablackcatstail,

In effect, Cloudflare would give protection against DDoS attacks before requests would even hit your servers. That much said you can implement mitigations on the reverse proxy itself. One example would be fail2ban.

I’m sure there are additional steps that you can take. I’m not a fan of Cloudflare because their free offering has some caveats and violating these could be problematic. I have a cloud VPS with a WireGuard tunnel back to my server. I don’t have to do anything ugly like port forwarding. The cloud VPS runs NGINX as a reverse proxy. It’s a relatively simple and effective setup.

operator,
operator avatar

Thanks! How do you handle that with internal DNS? I suppose you’d need to setup the exact same proxies on the internal and external server, and local DNS handles which one my domain it’s being resolved to?

ablackcatstail,

Right now the internal DNS I use has a TLD of .lan but that’s pretty much for my personal convenience. I access my websites by their FQDN internally with no issue. So I am not sure what your tring to achieve. Mind elaborating?

operator,
operator avatar

Of course! So in order to get maximum speed on your services, you wanna use a direct internal route when you're inside your net. My understanding is, that when using an external cloud VPS with a proxy, local clients go through unnecessary routing..

Local request --out--> external VPS (proxy) --request data from internal--> receive data on external proxy --send back--> local client

So what I am saying, all requests are unnecessarily routed through the external VPS. So one would have to create an exact duplicate reverse proxy internally to avoid leaving the net. When accessing domain.com, the internal DNS returns the local proxy IP, when outside you receive the cloud VPS IP.

Or am I missing something?

Thank you for taking the time!

ablackcatstail,

I have not converted my home network to use split-brain yet and that’s because I only just recently got Let’s Encrypt to work with the DNS-01 challenge which verifies domain ownership via a TXT record. Now that the DNS-01 challenge works perfectly, I can use split-brain DNS to resolve my example.com requests to internal IP addresses. What I am currently doing is as follows and it is inefficient and ugly!

Local request —> Internet --> VPS Proxy --> WireGuard tunnel --> Local Server --> WireGuard tunnel -> VPS Proxy -> Internet --> Local origin

Now that I have Let’s Encrypt working using the DNS-01 challenge, there will be significantly less latency. It should look something like this:

<pre style="background-color:#ffffff;">
<span style="color:#323232;">Local request --> Local DNS Server --> Local Server --> Local request
</span><span style="color:#323232;">                                         |
</span><span style="color:#323232;">                                         --> Local Server --> WireGuard Tunnel --> Internet
</span>

I hope this is helpful! This will reduce the amount of locally generated traffic that must transit the VPN tunnel bi-directionally.

ablackcatstail,

I just decided to go ahead and implement split-brain DNS this evening and it works perfectly. What are you using for your internal DNS server? If it is Unbound, the one that I am using, I can share my config with you. After implementing this, the speed of my services when being accessed from my internal network sped up by an order of magnitude. I shoulda done this earlier. 😆

operator,
operator avatar

That be amazing! I am currently not using anything (took down my homelab a while back) and planning on completely starting over fresh now.

I am most likely going with unbound! So if you could, that be great!

ablackcatstail,

Unbound is simple to configure. I will send you mine when I get home from work. You could probably easily adapt it.

ablackcatstail,

Here is a sample configuration that should work for you:

<pre style="background-color:#ffffff;">
<span style="color:#323232;">server:
</span><span style="color:#323232;">        interface: 127.0.0.1
</span><span style="color:#323232;">        interface: 192.168.1.1
</span><span style="color:#323232;">        do-udp: yes
</span><span style="color:#323232;">        do-tcp: yes
</span><span style="color:#323232;">        do-not-query-localhost: no
</span><span style="color:#323232;">        verbosity: 1
</span><span style="color:#323232;">        log-queries: yes
</span><span style="color:#323232;">
</span><span style="color:#323232;">        access-control: 0.0.0.0/0 refuse
</span><span style="color:#323232;">        access-control-view: 127.0.0.0/8 example
</span><span style="color:#323232;">        access-control-view: 192.168.1.0/24 example
</span><span style="color:#323232;">
</span><span style="color:#323232;">        hide-identity: yes
</span><span style="color:#323232;">        hide-version: yes
</span><span style="color:#323232;">        tcp-upstream: yes
</span><span style="color:#323232;">
</span><span style="color:#323232;">remote-control:
</span><span style="color:#323232;">        control-enable: yes
</span><span style="color:#323232;">        control-interface: /var/run/unbound.sock
</span><span style="color:#323232;">
</span><span style="color:#323232;">view:
</span><span style="color:#323232;">        name: "example"
</span><span style="color:#323232;">        local-zone: "example.com." inform
</span><span style="color:#323232;">        local-data: "example.com. IN A 192.168.1.2"
</span><span style="color:#323232;">        local-data: "www IN CNAME example.com."
</span><span style="color:#323232;">        local-data: "another.example.com. IN A 192.168.1.3"
</span><span style="color:#323232;">
</span><span style="color:#323232;">forward-zone:
</span><span style="color:#323232;">        name: "."
</span><span style="color:#323232;">        forward-addr: 8.8.8.8
</span><span style="color:#323232;">        forward-addr: 8.8.4.4
</span>

What makes the split-brain DNS work is if the request for resolution comes from the localhost or from inside your network, it will first go to the view section to see if there is any pertinent local data. So if you do a query from your home network, on say, example.com, it will return your internal IP address which in this case is 192.168.1.2

operator,
operator avatar

Appreciate it!

ablackcatstail,

Sure! Let me know how it goes. If you need to do something more complex for internal DNS records for more than just A records, then look at the unbound.conf man page for stub zones. If you need something even more flexible than stub zones, you can use Unbound as a full authoritative DNS server with auth-zones. As far as I know auth-zones can even do zone transfers AXFR style which is cool!

operator,
operator avatar

That’s becoming interesting once I’m setting up a slaves for failover & local proximity ^^ looking forward to deep diving into it

Distributed,

Lol, decided to ask chatGPT this question, turned out pretty well:

Alright, imagine you have a magic tunnel that can connect different places together. But this is not an ordinary tunnel that you can see or walk through. It’s a special tunnel that works with the internet!

You know when you want to visit a website on your tablet or computer, you type its address in a web browser, right? Well, sometimes websites need extra protection to stay safe from bad things on the internet. That’s where Cloudflare Tunnel comes in!

Cloudflare Tunnel is like a superhero that helps keep websites safe. It creates a secret passage between the website and Cloudflare’s special servers. When people try to visit the website, their requests go through this secret tunnel first.

Now, imagine there are some bad guys who want to do bad things to the website. They try to find the website, but all they see is the secret tunnel. They can’t see the website or know where it is. It’s like the website is hiding!

But good people, like you and me, can still find the website because we know the secret. We can use the magic tunnel to reach the website and see what’s there. Cloudflare Tunnel helps protect the website from the bad guys and lets the good people get through.

So, Cloudflare Tunnel is like a special secret tunnel on the internet that keeps websites safe from bad guys and helps the good people find them.

operator,
operator avatar

Haha! Explaining for dummies, I like it.

KairuByte,
@KairuByte@lemmy.world avatar

I mean… it’s not wrong.

Harvest6671,

I would also like to know this. Everyone talks about it but I have no idea how it’s different than anything I’m doing now. Is it like Tailscale?

operator,
operator avatar

One of the mysteries I am facing ^^ selfhost headscale? Tailscale? VPN? CF?

Too many options :D

deleted,

Try to selfhost tailscale

You can set it up in 10 minutes.

In iOS, you can make automations to connect after launching certain apps.

In Android, you can do split tunneling.

vividspecter,

Regular wireguard is fine as long as you’re not on CG-NAT, and doesn’t have any reliance on third party services.

ablackcatstail,

Tailscale and ZeroTier offer the least barriers to entry. They can both be setup quickly and easily when compared to traditional VPN.

Distributed,

Personally, I just wireguard in to my local net. No need to have CF snooping where they don’t need to.

It all depends on your use cases and what you (or your users) need to access.

operator,
operator avatar

One of my considerations is the privacy side… VPN or self hosted solution seems to be the waay better choice in that case.

EncryptKeeper,

Selfhost headscale, run a reverse proxy with let’s encrypt on a VPS and Tailscale that VPS to your local server, utilizing Tailscale’s ACLs to block all ports except for your desired ones. It’s exactly what CF tunnels is doing but you have far more control over your data and security.

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