Title: OpenBSD scripts to convert wg-quick VPN files
Author: Solène
Date: 27 April 2024
Tags: openbsd vpn security
Description: In this article, you will learn about scripts that
allowing using commercial VPN provider files on OpenBSD
# Introduction
If you use commercial VPN, you may have noticed they all provide
WireGuard configurations in the wg-quick format, this is not suitable
for an easy use in OpenBSD.
As I currently work a lot for a VPN provider, I often have to play with
configurations and I really needed a script to ease my work.
I made a shell script that turns a wg-quick configuration into a
hostname.if compatible file, for a full integration into OpenBSD. This
is practical if you always want to connect to a given VPN server, not
for temporary connections.
HTML OpenBSD manual pages: hostname.if
HTML Sourcehut project: wg-quick-to-hostname-if
# Usage
It is really easy to use, download the script and mark it executable,
then run it with your wg-quick configuration as a parameter, it will
output the hostname.if file to the standard output.
```
wg-quick-to-hostname-if fr-wg-001.conf | doas tee /etc/hostname.wg0
```
In the generated file, it uses a trick to dynamically figure the
current default route which is required to keep a non-vpn route to the
VPN gateway.
# Short VPN sessions
When I shared my script on mastodon, Carlos Johnson shared their own
script which is pretty cool and complementary to mine.
If you prefer to establish a VPN for a limited session, you may want to
take a look at his script.
HTML Carlos Johnson GitHub: file-wg-sh gist
# Prevent leaks
If you need your WireGuard VPN to be leakproof (= no network traffic
should leave the network interface outside the VPN if it's not toward
the VPN gateway), you should absolutely do the following:
* your WireGuard VPN should be on rdomain 0
* WireGuard VPN should be established on another rdomain
* use PF to block traffic on the other rdomain that is not toward the
VPN gateway
* use the VPN provider DNS or a no-log public DNS provider
HTML Older blog post: WireGuard and rdomains
# Conclusion
OpenBSD's ability to configure WireGuard VPNs with ifconfig has always
been an incredible feature, but it was not always fun to convert from
wg-quick files. But now, using a commercial VPN got a lot easier
thanks to a few piece of shell.