if-up.d files do not have effect on ubuntu 24.04 LTS

[francesco]

Some time ago I wrote a detailed answer to fix an error for lowering MTU size for a cisco-compatible VPN (here:https://unix.stackexchange.com/questions/768757/unable-to-ssh-into-remote-machine-but-able-to-ping-vpnc/768758#768758)

After upgrading to Ubuntu 24.04 LTS, I'm unable with the same steps to lower the MTU size.

In particular, if I run the following command from the terminal

sudo ifconfig your_tunnel_name mtu 1370 up

it seems to lower the MTU size.

However, the script under /etc/network/if-up.d is not automatically triggered.

Does something change with the newer Ubuntu version?

[Lukas Märdian (slyon)]

You filed the bug report against NetworkManager. But the "up.d" hook is called differently in NM, see https://netplan.io/faq#use-pre-up-post-up-etc-hook-scripts

If this is about /etc/network/if-up.d then it should be targeted towards the "ifupdown" package. I'm adding a corresponding bug task.

[francesco (u-user-prop)]

Thanks Lukas!

[Miroslav Zaťko (mirec-z)]

Triggering if-up.d scripts changed completely without mention in documentation.
For 23.10 scripts was triggered for each network interface separately. On boot it was with

* PHASE=post-up, IFACE=lo;
* PHASE=post-up, IFACE=virbr0;
* PHASE=post-up, IFACE=enx047bcb671ca9;
* PHASE=post-up, IFACE=docker0;
* PHASE=post-up, IFACE=wlp0s20f3

Later on connecting to openconnect/anyconnect it was triggered with
* PHASE=post-up, IFACE=vpn0

After upgrade to 24.04 it is triggered on boot only with:
* PHASE=post-up, IFACE=lo;
* PHASE=post-up, IFACE=-all

Nothing triggered after connecting to openconnect/anyconnect

https://bugs.launchpad.net/openconnect/+bug/2064028

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nicolas (bibi-tofu)]

It also looks like on 24.04, the if-up.d scripts aren't run at all when resuming from sleep.

Before 24.04:
- Boot
- My if-up.d script that triggers for "IFACE=wlp0s20f3" gets properly triggered (it adds an IP alias to this interface using "ip addr add").
- Put ubuntu to sleep
- Resume ubuntu
- My if-up.d script that triggers for "IFACE=wlp0s20f3" gets properly triggered.

After 24.04:
- Boot
- My if-up.d script that triggers for "IFACE=wlp0s20f3" gets properly triggered (it adds an IP alias to this interface using "ip addr add"). Apparently I could fix this by triggering this script with "IFACE=-all". For now I manually run the "ip addr add" command.
- Put ubuntu to sleep
- Resume ubuntu
- My if-up.d script that triggers for "IFACE=wlp0s20f3" is not called (not even with "IFACE=-all"). The IP alias disappeared, so the interface did go down and get back up, but the script wasn't called at all. For this I don't think I have a fix?