L2TP vpn to zyxel endpoint adds a wrong route - solved upstream in 1.20.8-

[Fabio Muzzi]

Since upgrading from 20.04 to 22.04, I have not been able to connect to an L2TP vpn that has a Zyxel firewall as the remote end.

The issue is explained here

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/946

And it's resolved upstream in networkmanager 1.40.10 and networkmanager-l2tp 1.20.8

[Douglas Kosovic (dkosovic)]

If you update network-manager-l2tp to 1.20.8 from the following PPA repository:
https://launchpad.net/~nm-l2tp/+archive/ubuntu/network-manager-l2tp

Are you still able to reproduce the issue?

Doug

[Fabio Muzzi (kurgan-kurgan)]

With the updated network-manager-l2tp it works.

Connecting to a Zyxel firewall it sets an arbitrary remote address of 10.64.64.64 for the remote PPP link address instead of the public address that the Zyxel devices passes us (wrongly) so now there is no more the issue with routing of the remote public address inside the VPN, which happened with the original network-manager-l2tp from Ubuntu 22.04

I have also tested a VPN to a Mikrotik device (that worked before) and it's still fine, so as far as I can say, it works using this PPA

[Douglas Kosovic (dkosovic)]

Glad to hear you got your VPN connection working and thanks for confirming it worked with the newer network-manager-l2tp.

I believe a reverse of the following commit will fix the version of networkmanager-l2tp that ships with Ubuntu 22.04 :
https://github.com/nm-l2tp/NetworkManager-l2tp/commit/95fdaa6dc8348ba7f63bcf7aa2ccc95b762c491d

To have it included I believe would require submitting a SRU which includes a proposed package with the patch, see:

https://wiki.ubuntu.com/StableReleaseUpdates

I've never had luck submitting a SRU unless lots of people voted for it and confirmed it fixed the issue.

I would recommend using the newer version from the aforementioned PPA. The newer version has many other bug fixes.

I've never had luck submitting a newer package to Ubuntu Backports, no users wanted to vote (or maybe only two or three), making it difficult to find a sponsor to upload the new package.

[Fabio Muzzi (kurgan-kurgan)]

Well, if it's so hard to have the bug fixed, I'll keep network-manager-l2tp from the PPA until the next dist-upgrade and then we'll see. Thanks a lot anyway, since now it works, at least.