How to configure OpenVPN#

Intended audience

staff members

The Software Heritage server and the VMs running on it are severely firewalled. To get onto their network unrestricted, a VPN based on OpenVPN is available.

The setup is client-server, with per-client certificates.

OpenVPN client configuration#

Raw OpenVPN#

Sample configuration file, e.g., /etc/openvpn/swh.conf:

ns-cert-type server
dev tun
proto udp
port 1194
log /var/log/openvpn.log
ca /etc/openvpn/keys/softwareheritage-ca.crt
cert /etc/openvpn/keys/softwareheritage.crt
key /etc/openvpn/keys/softwareheritage.key
user nobody
group nogroup

# If you are using resolvconf, add this:
# Make sure you add louvre to /etc/hosts to avoid issues in using the vpn-provided DNS server.
script-security 2
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf

# If you want the connection to persist when your network fails, add this:
ping-restart 10

In addition to the above configuration file, you will need to install the following 3 files under /etc/openvpn/keys (matching the paths within the sample above):

Activate the openvpn server, as root (on your machine), run:

NAME=swh  # or "work" as you wish
systemctl enable openvpn@$NAME.service
systemctl start openvpn@$NAME.service
systemctl status openvpn@$NAME.service

Note: Internally, the swh must match the /etc/openvpn/swh.conf filename. You can name it as you want (e.g work), just be consistent about it.

Excerpt of a successful start:

root@machine:~# systemctl status openvpn@swh.service``
openvpn@swh.service - OpenVPN connection to swh``
 Loaded: loaded (/lib/systemd/system/openvpn@.service; indirect; vendor preset: enabled)``
 Active: active (running) since Thu 2020-12-17 19:03:29 UTC; 22min ago``
   Docs: man:openvpn(8)``
         ``\ ````` <>`_
         ``\ ````` <>`_
 Main PID: 12302 (openvpn)``
   Status: "Initialization Sequence Completed"``
    Tasks: 1 (limit: 4915)``
   CGroup: /system.slice/system-openvpn.slice/openvpn@swh.service``
           └─12302 /usr/sbin/openvpn --daemon ovpn-swh --status /run/openvpn/swh.status 10 --cd /etc/openvpn --script-security 2 --config /etc/openvpn/swh.conf --writepid /run/openvpn/``

   Dec 17 19:03:29 machine systemd[1]: Starting OpenVPN connection to swh...
   Dec 17 19:03:29 machine systemd[1]: Started OpenVPN connection to swh.

Network Manager GUI#

You need network-manager-openvpn and network-manager-openvpn-gnome for the configuration gui.

nm-openvpn-base.png nm-openvpn-routes.png nm-openvpn-advanced-general.png nm-openvpn-advanced-security.png nm-openvpn-advanced-tls-auth.png

Obtaining a client certificate#

For users#

Generate a key pair (key + certificate signing request) using the following command:

openssl req -new -newkey rsa:2048 -nodes -keyout openvpn.key -out openvpn.csr -subj "/CN=<your username>"

Please replace with something that uniquely identifies the certificate.

Make sure openvpn.key is stored in a safe place (it’s your private key, which will allow anyone to connect to the VPN).

Provide the CSR file to a sysadmin through a reasonably authenticated medium.

For admins#

  • On the Method list, choose “Sign a certificate Signing Request”


Fetch the CSR file provided by the user, for instance with scp USERNAME.csr louvre:

  • Enter the user name on the descriptive name

  • Select “OpenVPN Software Heritage (louvre)” as Certificate Authority

  • Enter the duration, usually 10 years

  • Paste the csr

  • Validate

  • check the details of the csr and validate

Revoking a client certificate#

On the firewall (master) 1:

  • go to the bottom of the page

  • select the certificate to revoke

  • Add

The counter of revoked certificate should be increased by one on for the OpenVPN CSR on the CSR list.