Set up a personal VPN in the cloud
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Dan Guido 0aaca43019
Security Hardening and Certificate Authority Constraints (#14811)
* Security hardening and certificate authority constraints

This commit addresses Issues #75 and #14804 with defensive security
enhancements that provide additional protection layers for edge case
scenarios.

## Issue #75: Technically Constrain Root CA
- Add pathlen:0 basic constraints preventing subordinate CA creation
- Implement name constraints restricting certificate issuance to specific IPs
- Add extended key usage restrictions limiting CA scope to VPN certificates
- Separate client/server certificate extensions (serverAuth vs clientAuth)
- Enhanced CA with critical constraints for defense-in-depth when CA keys saved

## Issue #14804: Comprehensive SystemD Security Hardening
- WireGuard: Added systemd hardening as additional defense-in-depth
- StrongSwan: Enhanced systemd configuration complementing AppArmor profiles
- dnscrypt-proxy: Additional systemd security alongside AppArmor protection
- Applied privilege restrictions, filesystem isolation, and system call filtering

## Technical Changes
- CA certificate constraints only relevant when users opt to save CA keys
- SystemD hardening provides additional isolation layers beyond existing AppArmor
- Enhanced client certificate validation for iOS/macOS profiles
- Reliable AppArmor profile enforcement for Ubuntu 22.04

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Address PR review feedback and improve code quality

## Fixes Based on Review Feedback:

### Handler Consistency Issues
- Fix notification naming: "daemon reload" → "daemon-reload" for consistency
- Update deprecated syntax: `daemon_reload: yes` → `daemon_reload: true`

### Enhanced CA Certificate Constraints
- Add .mil and .int to excluded DNS domains for completeness
- Add .mil and .int to excluded email domains for consistency
- Add explanatory comment for openssl_constraint_random_id security purpose

## Technical Improvements:
- Ensures proper handler invocation across DNS and WireGuard services
- Provides more comprehensive CA name constraints protection
- Documents the security rationale for UUID-based CA constraints

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

* Address PR review feedback - improve documentation and fix duplicate key

- Add IPv6 documentation range (2001:db8::/32) to excluded ranges
- Add explanatory comment for CA name constraints defense-in-depth purpose
- Remove duplicate DisableMOBIKE key from iOS configuration
- Add comprehensive comments to iOS/macOS mobileconfig parameters
- Explain MOBIKE, redirect disabling, certificate type, and routing settings

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>
2025-08-04 20:22:41 -07:00
.github Bump actions/setup-python from 5.2.0 to 5.6.0 (#14806) 2025-08-04 10:24:59 -07:00
configs ECDSA fixed 2016-07-24 14:44:59 +03:00
docs docs: Add Windows client documentation and common error fix (#14787) 2025-08-03 15:20:58 -06:00
files/cloud-init feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
library Refactor WireGuard key management (#14803) 2025-08-03 18:24:12 -07:00
playbooks feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
roles Security Hardening and Certificate Authority Constraints (#14811) 2025-08-04 20:22:41 -07:00
scripts feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
tests Refactor WireGuard key management (#14803) 2025-08-03 18:24:12 -07:00
venvs on-build python venvs (#1199) 2018-11-22 13:04:58 -05:00
.ansible-lint Fix DigitalOcean cloud-init compatibility and deprecation warnings (#14801) 2025-08-03 14:25:47 -04:00
.dockerignore updating .dockerignore file (#14559) 2023-03-03 00:54:49 -04:00
.gitignore fix: Correct Azure requirements file path to resolve deployment failures (#14781) 2025-08-03 04:56:06 -04:00
.yamllint feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
algo Refactor to support Ansible 2.8 (#1549) 2019-09-28 08:10:20 +08:00
algo-docker.sh chore: Conservative dependency updates for Jinja2 security fix (#14792) 2025-08-03 07:45:26 -04:00
algo-showenv.sh Refactor to support Ansible 2.8 (#1549) 2019-09-28 08:10:20 +08:00
ansible.cfg feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
CHANGELOG.md Update CHANGELOG.md 2020-08-06 19:32:23 +03:00
CLAUDE.md Add Claude Code GitHub Workflow (#14798) 2025-08-03 08:01:41 -04:00
cloud.yml Ansible upgrade 6.1 (#14500) 2022-07-30 15:01:24 +03:00
CODEOWNERS Add CODEOWNERS file (#14599) 2023-07-25 14:55:28 +03:00
config.cfg feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
CONTRIBUTING.md Doc improvements (#479) 2017-04-23 14:54:54 -04:00
deploy_client.yml Ansible upgrade 6.1 (#14500) 2022-07-30 15:01:24 +03:00
Dockerfile upgrade ansible to 9.1.0 (#14673) 2023-12-08 01:54:08 +03:00
input.yml Ubuntu 22.04 support (#14579) 2023-05-17 03:04:23 +03:00
install.sh fix: Fix shellcheck POSIX sh issue and make ansible-lint stricter (#14789) 2025-08-03 07:04:04 -04:00
inventory Refactor to support Ansible 2.8 (#1549) 2019-09-28 08:10:20 +08:00
LICENSE AGPLv3 change (#1351) 2019-03-17 11:19:24 -04:00
logo.png Closes #82, again 2017-02-07 16:35:23 -05:00
main.yml feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
Makefile Docker makefile (#1553) 2019-08-19 15:07:24 +02:00
PERFORMANCE.md feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
PULL_REQUEST_TEMPLATE.md Update PULL_REQUEST_TEMPLATE.md 2019-10-07 13:11:33 +02:00
pyproject.toml feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
README.md docs: Add Windows client documentation and common error fix (#14787) 2025-08-03 15:20:58 -06:00
requirements.txt feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
requirements.yml fix: Fix shellcheck POSIX sh issue and make ansible-lint stricter (#14789) 2025-08-03 07:04:04 -04:00
SECURITY.md Create SECURITY.md (#14669) 2023-12-12 19:17:59 +03:00
server.yml Fix IPv6 address selection on BSD systems (#14786) 2025-08-03 17:15:27 -07:00
users.yml fix: Fix shellcheck POSIX sh issue and make ansible-lint stricter (#14789) 2025-08-03 07:04:04 -04:00
uv.lock feat: Add comprehensive performance optimizations to reduce deployment time by 30-60% 2025-08-03 16:42:17 -07:00
Vagrantfile Bump ansible from 2.9.20 to 4.4.0 (#14272) 2021-10-31 12:58:35 +03:00

Algo VPN

Twitter

Algo VPN is a set of Ansible scripts that simplify the setup of a personal WireGuard and IPsec VPN. It uses the most secure defaults available and works with common cloud providers. See our release announcement for more information.

Features

  • Supports only IKEv2 with strong crypto (AES-GCM, SHA2, and P-256) for iOS, macOS, and Linux
  • Supports WireGuard for all of the above, in addition to Android and Windows 11
  • Generates .conf files and QR codes for iOS, macOS, Android, and Windows WireGuard clients
  • Generates Apple profiles to auto-configure iOS and macOS devices for IPsec - no client software required
  • Includes a helper script to add and remove users
  • Blocks ads with a local DNS resolver (optional)
  • Sets up limited SSH users for tunneling traffic (optional)
  • Based on current versions of Ubuntu and strongSwan
  • Installs to DigitalOcean, Amazon Lightsail, Amazon EC2, Vultr, Microsoft Azure, Google Compute Engine, Scaleway, OpenStack, CloudStack, Hetzner Cloud, Linode, or your own Ubuntu server (for more advanced users)

Anti-features

  • Does not support legacy cipher suites or protocols like L2TP, IKEv1, or RSA
  • Does not install Tor, OpenVPN, or other risky servers
  • Does not depend on the security of TLS
  • Does not claim to provide anonymity or censorship avoidance
  • Does not claim to protect you from the FSB, MSS, DGSE, or FSM

Deploy the Algo Server

The easiest way to get an Algo server running is to run it on your local system or from Google Cloud Shell and let it set up a new virtual machine in the cloud for you.

  1. Setup an account on a cloud hosting provider. Algo supports DigitalOcean (most user friendly), Amazon Lightsail, Amazon EC2, Vultr, Microsoft Azure, Google Compute Engine, Scaleway, DreamCompute, Linode, or other OpenStack-based cloud hosting, Exoscale or other CloudStack-based cloud hosting, or Hetzner Cloud.

  2. Get a copy of Algo. The Algo scripts will be installed on your local system. There are two ways to get a copy:

    • Download the ZIP file. Unzip the file to create a directory named algo-master containing the Algo scripts.

    • Use git clone to create a directory named algo containing the Algo scripts:

      git clone https://github.com/trailofbits/algo.git
      
  3. Install Algo's core dependencies. Algo requires that Python 3.10 and at least one supporting package are installed on your system.

    • macOS: Big Sur (11.0) and higher includes Python 3 as part of the optional Command Line Developer Tools package. From Terminal run:

      python3 -m pip install --user --upgrade virtualenv
      

      If prompted, install the Command Line Developer Tools and re-run the above command.

      For macOS versions prior to Big Sur, see Deploy from macOS for information on installing Python 3 .

    • Linux: Recent releases of Ubuntu, Debian, and Fedora come with Python 3 already installed. If your Python version is not 3.10, then you will need to use pyenv to install Python 3.10. Make sure your system is up-to-date and install the supporting package(s):

      • Ubuntu and Debian:

        sudo apt install -y --no-install-recommends python3-virtualenv file lookup
        

        On a Raspberry Pi running Ubuntu also install libffi-dev and libssl-dev.

      • Fedora:

        sudo dnf install -y python3-virtualenv
        
    • Windows: Use the Windows Subsystem for Linux (WSL) to create your own copy of Ubuntu running under Windows from which to install and run Algo. See the Windows documentation for more information.

  4. Install Algo's remaining dependencies. You'll need to run these commands from the Algo directory each time you download a new copy of Algo. In a Terminal window cd into the algo-master (ZIP file) or algo (git clone) directory and run:

    python3 -m virtualenv --python="$(command -v python3)" .env &&
      source .env/bin/activate &&
      python3 -m pip install -U pip virtualenv &&
      python3 -m pip install -r requirements.txt
    

    On Fedora first run export TMPDIR=/var/tmp, then add the option --system-site-packages to the first command above (after python3 -m virtualenv). On macOS install the C compiler if prompted.

  5. Set your configuration options. Open the file config.cfg in your favorite text editor. Specify the users you wish to create in the users list. Create a unique user for each device you plan to connect to your VPN.

Note: [IKEv2 Only] If you want to add or delete users later, you must select yes at the Do you want to retain the keys (PKI)? prompt during the server deployment. You should also review the other options before deployment, as changing your mind about them later may require you to deploy a brand new server.

  1. Start the deployment. Return to your terminal. In the Algo directory, run ./algo and follow the instructions. There are several optional features available, none of which are required for a fully functional VPN server. These optional features are described in greater detail in here.

That's it! You will get the message below when the server deployment process completes. Take note of the p12 (user certificate) password and the CA key in case you need them later, they will only be displayed this time.

You can now set up clients to connect to your VPN. Proceed to Configure the VPN Clients below.

    "#                          Congratulations!                            #"
    "#                     Your Algo server is running.                     #"
    "#    Config files and certificates are in the ./configs/ directory.    #"
    "#              Go to https://whoer.net/ after connecting               #"
    "#        and ensure that all your traffic passes through the VPN.      #"
    "#                     Local DNS resolver 172.16.0.1                    #"
    "#        The p12 and SSH keys password for new users is XXXXXXXX       #"
    "#        The CA key password is XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX       #"
    "#      Shell access: ssh -F configs/<server_ip>/ssh_config <hostname>  #"

Configure the VPN Clients

Certificates and configuration files that users will need are placed in the configs directory. Make sure to secure these files since many contain private keys. All files are saved under a subdirectory named with the IP address of your new Algo VPN server.

Apple Devices

WireGuard is used to provide VPN services on Apple devices. Algo generates a WireGuard configuration file, wireguard/<username>.conf, and a QR code, wireguard/<username>.png, for each user defined in config.cfg.

On iOS, install the WireGuard app from the iOS App Store. Then, use the WireGuard app to scan the QR code or AirDrop the configuration file to the device.

On macOS Mojave or later, install the WireGuard app from the Mac App Store. WireGuard will appear in the menu bar once you run the app. Click on the WireGuard icon, choose Import tunnel(s) from file..., then select the appropriate WireGuard configuration file.

On either iOS or macOS, you can enable "Connect on Demand" and/or exclude certain trusted Wi-Fi networks (such as your home or work) by editing the tunnel configuration in the WireGuard app. (Algo can't do this automatically for you.)

Installing WireGuard is a little more complicated on older version of macOS. See Using macOS as a Client with WireGuard.

If you prefer to use the built-in IPSEC VPN on Apple devices, or need "Connect on Demand" or excluded Wi-Fi networks automatically configured, then see Using Apple Devices as a Client with IPSEC.

Android Devices

WireGuard is used to provide VPN services on Android. Install the WireGuard VPN Client. Import the corresponding wireguard/<name>.conf file to your device, then setup a new connection with it. See the Android setup instructions for more detailed walkthrough.

Windows

WireGuard is used to provide VPN services on Windows. Algo generates a WireGuard configuration file, wireguard/<username>.conf, for each user defined in config.cfg.

Install the WireGuard VPN Client. Import the generated wireguard/<username>.conf file to your device, then setup a new connection with it. See the Windows setup instructions for more detailed walkthrough and troubleshooting.

Linux WireGuard Clients

WireGuard works great with Linux clients. See this page for an example of how to configure WireGuard on Ubuntu.

Linux strongSwan IPsec Clients (e.g., OpenWRT, Ubuntu Server, etc.)

Please see this page.

OpenWrt Wireguard Clients

Please see this page.

Other Devices

Depending on the platform, you may need one or multiple of the following files.

  • ipsec/manual/cacert.pem: CA Certificate
  • ipsec/manual/.p12: User Certificate and Private Key (in PKCS#12 format)
  • ipsec/manual/.conf: strongSwan client configuration
  • ipsec/manual/.secrets: strongSwan client configuration
  • ipsec/apple/.mobileconfig: Apple Profile
  • wireguard/.conf: WireGuard configuration profile
  • wireguard/.png: WireGuard configuration QR code

Setup an SSH Tunnel

If you turned on the optional SSH tunneling role, then local user accounts will be created for each user in config.cfg and SSH authorized_key files for them will be in the configs directory (user.pem). SSH user accounts do not have shell access, cannot authenticate with a password, and only have limited tunneling options (e.g., ssh -N is required). This ensures that SSH users have the least access required to setup a tunnel and can perform no other actions on the Algo server.

Use the example command below to start an SSH tunnel by replacing <user> and <ip> with your own. Once the tunnel is setup, you can configure a browser or other application to use 127.0.0.1:1080 as a SOCKS proxy to route traffic through the Algo server:

ssh -D 127.0.0.1:1080 -f -q -C -N <user>@algo -i configs/<ip>/ssh-tunnel/<user>.pem -F configs/<ip>/ssh_config

SSH into Algo Server

Your Algo server is configured for key-only SSH access for administrative purposes. Open the Terminal app, cd into the algo-master directory where you originally downloaded Algo, and then use the command listed on the success message:

ssh -F configs/<ip>/ssh_config <hostname>

where <ip> is the IP address of your Algo server. If you find yourself regularly logging into the server then it will be useful to load your Algo ssh key automatically. Add the following snippet to the bottom of ~/.bash_profile to add it to your shell environment permanently:

ssh-add ~/.ssh/algo > /dev/null 2>&1

Alternatively, you can choose to include the generated configuration for any Algo servers created into your SSH config. Edit the file ~/.ssh/config to include this directive at the top:

Include <algodirectory>/configs/*/ssh_config

where <algodirectory> is the directory where you cloned Algo.

Adding or Removing Users

If you chose to save the CA key during the deploy process, then Algo's own scripts can easily add and remove users from the VPN server.

  1. Update the users list in your config.cfg
  2. Open a terminal, cd to the algo directory, and activate the virtual environment with source .env/bin/activate
  3. Run the command: ./algo update-users

After this process completes, the Algo VPN server will contain only the users listed in the config.cfg file.

Additional Documentation

Setup Instructions for Specific Cloud Providers

Install and Deploy from Common Platforms

Setup VPN Clients to Connect to the Server

  • Setup Windows clients
  • Setup Android clients
  • Setup Linux clients with Ansible
  • Setup Ubuntu clients to use WireGuard
  • Setup Linux clients to use IPsec
  • Setup Apple devices to use IPsec
  • Setup Macs running macOS 10.13 or older to use WireGuard

Advanced Deployment

If you've read all the documentation and have further questions, create a new discussion.

Endorsements

I've been ranting about the sorry state of VPN svcs for so long, probably about time to give a proper talk on the subject. TL;DR: use Algo.

-- Kenn White

Before picking a VPN provider/app, make sure you do some research https://research.csiro.au/ng/wp-content/uploads/sites/106/2016/08/paper-1.pdf ... or consider Algo

-- The Register

Algo is really easy and secure.

-- the grugq

I played around with Algo VPN, a set of scripts that let you set up a VPN in the cloud in very little time, even if you dont know much about development. Ive got to say that I was quite impressed with Trail of Bits approach.

-- Romain Dillet for TechCrunch

If youre uncomfortable shelling out the cash to an anonymous, random VPN provider, this is the best solution.

-- Thorin Klosowski for Lifehacker

Support Algo VPN

PayPal Patreon

All donations support continued development. Thanks!

  • We accept donations via PayPal and Patreon.
  • Use our referral code when you sign up to Digital Ocean for a $10 credit.
  • We also accept and appreciate contributions of new code and bugfixes via Github Pull Requests.

Algo is licensed and distributed under the AGPLv3. If you want to distribute a closed-source modification or service based on Algo, then please consider purchasing an exception . As with the methods above, this will help support continued development.