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Cloudflare tunnel

Exposing your local server on the Internet (clearnet) has various solutions, but the Cloudflare Tunnel stands out as the easiest and most cost-effective option. Traditionally, configuring Firewalls, using Tor, or setting up an SSH reverse tunnel to a public VPS were common approaches, each with its challenges and costs. Cloudflare Tunnel offers an alternative, though it acts as a middleman and can access or modify your traffic.

{% hint style="warning" %} Cost: Paid service {% endhint %}

{% hint style="warning" %} Difficulty: Medium {% endhint %}

With Cloudflare Tunnel, you gain low latency access to your server on clearnet, without the need for complex firewall or router configurations, dynamic DNS, or relying on an internet service provider.

Cloudflare Tunnel ensures secure connectivity without exposing your server's publicly routable IP address. Instead, a lightweight daemon, cloudflared, creates outbound-only connections to Cloudflare's global network. This establishes persistent tunnels that route traffic to DNS records. You can run multiple cloudflared processes within a tunnel, connecting your resources securely to Cloudflare's nearest data center.

Requirements

Before you start, make sure you:

Buy a domain name

  • Buy a domain or use an existing one, there are different options to buy a domain, to this example, we will use Namecheap
    • Go to the Namecheap, search your wish domain between available, and follow the registration and buying process (you can pay using Bitcoin onchain), the price depends on the domain extensions chosen, a common extension like .com or .net generally has an annual cost between 10€ and 20€, but some less common extensions may have higher prices. In general, the most common extensions like .com, .net, and .org usually have low costs due to their popularity and availability. However, other less common extensions, such as .xyz or .online, are often offered at lower prices to attract more users.

Create an account on Cloudflare

  • Create an account on Cloudflare and add the recently created domain to it:
    • In the top navigation bar, click [Add site]
    • Enter your domain (example.com) and then click on the [Add site] button again
    • Select your plan level. The free plan is enough for this case of use. For more details on features and pricing of available plans, refer to the Plans page. Click Continue
    • Click Done, take note of the nameservers assigned to your account
    • On Overview, locate the nameserver names in 2

Change the domain nameservers to Cloudflare

  • Before your domain can begin using Cloudflare for DNS resolution, all requests should be redirected to Cloudflare’s network first, where Access policies can be applied. You need to add these nameservers to your registrar (Namecheap in our case)
    • Access your Namecheap account or the registrar selected, from the left sidebar, select Dashboard, and click on the Manage button next to your domain
    • Staying in the Domain tab, go to the Nameservers section, select CustomDNS, type the nameservers provided for Cloudflare before, and click on the green checkmark to save the changes

  • Make sure DNSSEC is disabled at this point
    • Select the Advanced DNS tab and find the DNSSEC section
    • Toggle the button to the left if are to the right

{% hint style="info" %} Once all of this is done, you need to wait for the registrar to update the nameservers. This process can take up to 24 hours, but it is usually much more immediate. In any case, Cloudflare will send an email when the process is finished {% endhint %}

Example of email notification received from Cloudflare

Check DNS records

  • From the left sidebar, select Websites, click on your site added, and again from the new left sidebar click on DNS -> Records

{% hint style="info" %} You can add a new record manually by clicking on the Add record button. More later we will use this. Right now you will not have any record {% endhint %}

{% hint style="info" %} Keep this Cloudflare session open, we will add and modify some registries to configure the tunnel {% endhint %}

Installation

  • With user admin, go to the temporary folder
cd /tmp
  • Set a temporary version environment variable to the installation
VERSION=2024.6.1
  • Download Cloudflare Tunnel Client (Cloudflared)
wget https://github.com/cloudflare/cloudflared/releases/download/$VERSION/cloudflared-linux-amd64.deb
  • Use the deb package manager to install it
sudo dpkg -i cloudflared-linux-amd64.deb
  • Check the correct installation
cloudflared --version

Example of expected output:

> cloudflared version 2023.6.1 (built 2023-06-20-0926 UTC)
  • Remove the package installation file
sudo rm cloudflared-linux-amd64.deb

{% hint style="info" %} If you come to update this is the final step {% endhint %}

Authenticate on Cloudflare and authorize

  • With user admin, authenticate Cloudflared with your Cloudflare account
cloudflared tunnel login

Example of expected output:

Please open the following URL and log in with your Cloudflare account:

https://dash.cloudflare.com/argotunnel?aud=&callback=https%3A%2F%2Flogin.cloudflareaccess.org%2FCbH_YLs-WM2zIR5j4NahjstGErge5AE79YIBNiZsV1Y%4D

Leave cloudflared running to download the cert automatically.
You have successfully logged in.
If you wish to copy your credentials to a server, they have been saved to:
/home/admin/.cloudflared/cert.pem

{% hint style="info" %} Leave Cloudflared running to download the cert automatically while you complete the authentication on the Cloudflare account {% endhint %}

  • In the same browser session with the Cloudflare account already open, enter the URL of the prompt provided earlier. Then, select your pre-configured site on Cloudflare to authorize the tunnel for that site

  • Authorize its connection

  • Go back to the MiniBolt terminal session, and you will see this:

Expected output:

> You have successfully logged in.
> If you wish to copy your credentials to a server, they have been saved to:
> /home/admin/.cloudflared/cert.pem

Create a tunnel and give it a name 

cloudflared tunnel create <NAME>

{% hint style="info" %} Suggestion: <NAME> = miniboltunnel {% endhint %}

Example of expected output:

Tunnel credentials written to /home/admin/.cloudflared/<UUID>.json. cloudflared chose this file based on where your origin certificate was found. Keep this file secret. To revoke these credentials, delete the tunnel.

Created tunnel <NAME> with id <UUID>

{% hint style="info" %} Take note of the tunnel ID -><UUID>: e.g: 8666c35d-6ac3-4b39-9324-12ae32ce64a7 you will need it later {% endhint %}

  • Ensure that the tunnel has been created
cloudflared tunnel list

Example of expected output:

You can obtain more detailed information for each tunnel with `cloudflared tunnel info <name/uuid>`
ID                                      NAME              CREATED               CONNECTIONS
8666c35d-6ac3-4b39-9324-12ae32ce64a7    miniboltunnel     2023-04-01T15:44:48Z
  • You can obtain more detailed information about the tunnel with
cloudflared tunnel info <NAME>

Example of expected output:

NAME:     miniboltunnel
ID:       8666c35d-6ac3-4b39-9324-12ae32ce64a7
CREATED:  2023-07-09 19:16:12.744487 +0000 UTC

CONNECTOR ID                         CREATED              ARCHITECTURE VERSION   ORIGIN IP      EDGE
8666c35d-6ac3-4b39-9324-12ae32ce64a7 2023-07-10T16:20:41Z linux_amd64  2023.6.1 <yourpublicip>

Start routing traffic

  • Now assign a CNAME record that points traffic to your tunnel subdomain

{% hint style="info" %}

If you want to tunnel only a specific service, you can choose the final subdomain for that service, for example, if you going to expose only the BTC RPC Explorer, choose explorer.<domain.com> or if you want to expose only the BTCpay Server, choose btcpay.<domain.com>

Replace <UUID> for your one obtained before {% endhint %}

cloudflared tunnel route dns <UUID> subdomain.domain.com

Example of expected output:

> 2023-07-09T18:01:07Z INF Added CNAME explorer.domain.com which will route to this tunnel tunnelID=8666c35d-6ac3-4b39-9324-12ae32ce64a7

Configuration

We will create a configuration file in your .cloudflared directory. This file will configure the tunnel to route traffic from a given origin to the hostname of your choice. We will use ingress rules to let you specify which local services traffic should be proxied to.

  • Staying with user admin, create config.yml
nano /home/admin/.cloudflared/config.yml
  • Here you should choose services that you want to expose publicly. This is only an example, so replace the ingress rules with your preferences. For example, you can replace btcpay or explorer with your name (subdomain) chosen for the service, and <domain.com> with the domain, you purchased previously. Ensure to replace <UUID> with your obtained before
# MiniBolt: cloudflared configuration
# /home/admin/.cloudflared/config.yml

tunnel: <UUID>
credentials-file: /home/admin/.cloudflared/<UUID>.json

ingress:

# BTCPay Server
  - hostname: btcpay.<domain.com>
    service: http://localhost:23000

# BTC RPC Explorer
  - hostname: explorer.<domain.com>
    service: http://localhost:3002

  - service: http_status:404

{% hint style="info" %}

  1. Electrum server are not supported using Cloudflared

  1. For security reasons, you shouldn't expose publically the administration access services using Cloudflared e.g SSH or Thunderhub, for these cases you should use Wireguard VPN

  2. If you want to expose only a service, you can delete or comment the associated lines of other services, always maintaining the "- service: http_status:404" line at the end of the rules. Example, expose only BTCPay Server, the comment the associated lines for BTC RPC Explorer:

    # BTC RPC Explorer
#  - hostname: explorer.<domain.com>
#    service: http://localhost:3002

{% endhint %}

Configure Cloudflare DNS records

  • Now, we go back to the Cloudflare DNS records table to do modifications.

If you wanted to expose 2 services or more, that is to say, you ingressed more than one service on the ingress rules, follow the next steps, if not, you can only check the current recently created registry or jump directly to the next Increase the maximum UDP Buffer Sizes section:

  1. Edit the existing CNAME record that was recently created, and replace the name value with the name of the first or one of the services selected, or keep it if it's correct. For example, if you selected btcpay, keep the existing target content, which is the UUID of your tunnel
  2. Add a new record by selecting CNAME type.Enter the second subdomain selected in the second ingress rule e.g explorer, in the name box, and in the target content, enter the UUID of your tunnel (the same content as before)
  3. Ensure you have enabled Proxy for each record you have added (Proxy status: Proxied)

Example of DNS record table:

Increase the maximum UDP Buffer Sizes

Experiments have shown that QUIC transfers on high-bandwidth connections can be limited by the size of the UDP receive and send buffer.

  • With user admin, increase the maximum buffer size by editing the next file to add kernel parameters
sudo nano /etc/sysctl.conf
  • Here are the lines you’ll want to add at the end of the file. Save and exit
net.core.rmem_max=2500000
net.core.wmem_max=2500000
  • Then apply the changes with
sudo sysctl --system

{% hint style="info" %} These parameters would increase the maximum send and receive buffer size to roughly 2.5 MB {% endhint %}

Create systemd service

  • Create the configuration file in the nano text editor and copy the following content. Save and exit
sudo nano /etc/systemd/system/cloudflared.service
# MiniBolt: systemd unit for Cloudflared
# /etc/systemd/system/cloudflared.service

[Unit]
Description=Cloudflared
Requires=network-online.target
After=network-online.target

[Service]
ExecStart=/usr/bin/cloudflared --no-autoupdate --config /home/admin/.cloudflared/config.yml tunnel run

# Process management
####################
Type=notify
TimeoutStartSec=0

[Install]
WantedBy=multi-user.target
  • Enable autoboot (optional)
sudo systemctl enable cloudflared
  • Prepare cloudflared monitoring by the systemd journal and checking the logging output. You can exit monitoring at any time with Ctrl-C
journalctl -fu cloudflared

{% hint style="info" %} Keep this terminal open, you'll need to come back here on the next step to monitor the logs {% endhint %}

Run

To keep an eye on the software movements, start your SSH program (eg. PuTTY) a second time, connect to the MiniBolt node, and log in as admin. Run the tunnel to proxy incoming traffic from the tunnel to any number of services running locally on your origin

  • Start the service
sudo systemctl start cloudflared
Example of expected output on the first terminal with journalctl -fu cloudflared ⬇️ 
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Starting tunnel tunnelID=8666c35d-6ac3-4b39-9324-12ae32ce64a7
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Version 2023.6.1
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF GOOS: linux, GOVersion: go1.19.6, GoArch: amd64
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Settings: map[config:/home/admin/.cloudflared/config.yml cred-file:/home/admin/.cloudflared/8666c35d-6ac3-4b39-9324-12ae32ce64a7.json credentials-file:/home/admin/.cloudflared/8666c35d-6ac3-4b39-9324-12ae32ce64a7.json no-autoupdate:true]
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Generated Connector ID: ca7ebf91-844d-4025-89f0-e28df084d0a2
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF cloudflared will not automatically update if installed by a package manager.
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Initial protocol quic
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF ICMP proxy will use 192.168.1.87 as source for IPv4
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF ICMP proxy will use fe80::42a8:f0ff:feb0:aa4d in zone eno1 as source for IPv6
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023-07-10T16:20:40Z INF Starting metrics server on 127.0.0.1:46345/metrics
Jul 10 18:20:40 minibolt cloudflared[3405663]: 2023/07/10 18:20:40 failed to sufficiently increase receive buffer size (was: 208 kiB, wanted: 2048 kiB, got: 416 kiB). See https://github.com/quic-go/quic-go/wiki/UDP-Receive-Buffer-Size for details.
Jul 10 18:20:41 minibolt cloudflared[3405663]: 2023-07-10T16:20:41Z INF Registered tunnel connection connIndex=0 connection=0c293573-9581-4087-ab56-504d7eca57a1 event=0 ip=198.41.200.23 location=MAD protocol=quic
Jul 10 18:20:41 minibolt systemd[1]: Started cloudflared.
Jul 10 18:20:41 minibolt cloudflared[3405663]: 2023-07-10T16:20:41Z INF Registered tunnel connection connIndex=1 connection=cb1e7bb6-9051-43da-802e-1791687f7385 event=0 ip=198.41.192.57 location=MRS protocol=quic
Jul 10 18:20:43 minibolt cloudflared[3405663]: 2023-07-10T16:20:43Z INF Registered tunnel connection connIndex=2 connection=749064a4-fe1d-4c07-b0b9-71dbc0bcbe3a event=0 ip=198.41.192.227 location=MRS protocol=quic
Jul 10 18:20:43 minibolt cloudflared[3405663]: 2023-07-10T16:20:43Z INF Registered tunnel connection connIndex=3 connection=00f2ca81-1dd1-4695-9857-6815b376855b event=0 ip=198.41.200.33 location=MAD protocol=quic
  • Now point your browser to the hostnames created in your config.yml e.g https://explorer.domain.com or https://btcpay.domain.com and check if it resolves correctly to the local service

{% hint style="info" %} You should see the service properly running as if it were a local connection {% endhint %}

Ensure Cloudflared is listening on the random port assigned:

sudo ss -tulpn | grep LISTEN | grep cloudflared

Example of expected output:

> tcp   LISTEN 0      4096       127.0.0.1:37599      0.0.0.0:*    users:(("cloudflared",pid=311164,fd=3))

Upgrade

  • With user admin, stop Cloudflared
sudo systemctl stop cloudflared
  • Check the current version of Cloudflared
cloudflared --version
  • Follow again the installation section of this guide, replacing the environment variable "VERSION=x.xx" value for the latest if it has not been already changed in this guide
  • Start Cloudflared again
sudo systemctl start cloudflared

{% hint style="info" %} Monitor logs with journalctl -fu cloudflared to ensure that all is still working well {% endhint %}

Uninstall

  • With user admin, stop the Cloudflared
sudo systemctl stop cloudflared
  • Use the deb package manager to uninstall Cloudflared
sudo dpkg -r cloudflared

Example of expected output:

> (Reading database ... 74004 files and directories currently installed.)
> Removing cloudflared (2023.7.2) ...
> Processing triggers for man-db (2.10.2-1) ...

Port reference

Post Protocol Use
Random TCP Random port