I am migrating from Windows to Linux desktop since a while. One of the last things are to complete by setting up OpenVPN tunnels to IPFire. Using them under Windows with OpenVPN 2.4 client worked flawlessly without trouble.
I am using Debian with Cinnamon, making use of the Gnome Networkmanager. After installing OpenVPN by sudo apt install network-manager-openvpn-gnome , I was principally able to setup an OpenVPN tunnel, but I stumbled though.
When setting up my first OpenVPN connection, I got the error message (original German message) “Konfigurationsfehler: Argument 1 für >>mssfix<< ist ungültig. Eine Zahl wird erwartet.”, translation “configuration error: argument 1 for >>mssfix<< is invalid. A number is expected.”
Looking into the related ovpn file generated by IPFire, I do find a number, which is “0”. This is a number! Reading the official OpenVPN documentation, I decided to delete this parameter line from the file. And it seems to work!
A couple of questions…
- Comparing older configuration files with the one used for testing under Linux, I found that the option mssfix is not available in older configuration files. So why was this parameter added?
- Why is the mssfix parameter set to 0 by IPFire? Reading the documentation, this does not make sense with me.
- Should I keep the configuration file without the mssfix parameter?