[Solved] Make NetworkManager not create tun interface

Beemo · 2026-01-09 22:05:06

Is there a way to make NetworkManager apply a profile to a tun interface, but not create a new tun interface when the original one disappears and deactivate the profile instead?
I have a software that creates a tun interface and assigns it an IP4, and a NetworkManager profile that configures everything else (DNS, route, route-rules). I want the profile to activate / be applied when I run the software to create the tun interface, and deactivate when the software closes and removes the interface. However, currently NM creates a new interface when the original one is removed and stays up.

NetworkManager[794]: <info>  [1767995913.6539] device (ss-tun): state change: activated -> unmanaged (reason 'unmanaged', managed-type: 'removed')
NetworkManager[794]: <info>  [1767995913.6550] policy: auto-activating connection 'ss-tun' (32fa7031-9fa5-43ad-b21e-f682fb5e1668)
NetworkManager[794]: <info>  [1767995913.6565] device (ss-tun): state change: unmanaged -> unavailable (reason 'managed', managed-type: 'external')
NetworkManager[794]: <info>  [1767995913.6577] device (ss-tun): state change: unavailable -> disconnected (reason 'user-requested', managed-type: 'full')
NetworkManager[794]: <info>  [1767995913.6581] device (ss-tun): Activation: starting connection 'ss-tun' (32fa7031-9fa5-43ad-b21e-f682fb5e1668)
NetworkManager[794]: <info>  [1767995913.6584] device (ss-tun): state change: disconnected -> prepare (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995913.6587] device (ss-tun): state change: prepare -> config (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995913.6591] device (ss-tun): state change: config -> ip-config (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995915.6619] device (ss-tun): state change: ip-config -> ip-check (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995915.6642] device (ss-tun): state change: ip-check -> secondaries (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995915.6645] device (ss-tun): state change: secondaries -> activated (reason 'none', managed-type: 'full')
NetworkManager[794]: <info>  [1767995915.6652] device (ss-tun): Activation: successful, device activated.

Another issue in the post is now split to https://bbs.archlinux.org/viewtopic.php?pid=2282293

Last edited by Beemo (Yesterday 23:19:46)

seth · 2026-01-09 22:25:13

"nmcli device down ss-tun"?
Are you btw looking for https://archlinux.org/packages/extra/x8 … trongswan/ ?

Beemo · 2026-01-09 22:45:49

I just tried nmcli dev down, but it deactivates the connection too, and once the tun interface appears again the profile is not activated:

NetworkManager[794]: <info>  [1767998506.4724] device (ss-tun): state change: unmanaged -> unavailable (reason 'connection-assumed', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.4727] device (ss-tun): state change: unavailable -> disconnected (reason 'connection-assumed', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.4733] device (ss-tun): Activation: starting connection 'ss-tun' (52d2a421-4dba-4025-9674-78096a192d96)
NetworkManager[794]: <info>  [1767998506.4750] device (ss-tun): state change: disconnected -> prepare (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.4751] device (ss-tun): state change: prepare -> config (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.4752] device (ss-tun): state change: config -> ip-config (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.4755] device (ss-tun): state change: ip-config -> ip-check (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.5003] device (ss-tun): state change: ip-check -> secondaries (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.5005] device (ss-tun): state change: secondaries -> activated (reason 'none', managed-type: 'external')
NetworkManager[794]: <info>  [1767998506.5007] device (ss-tun): Activation: successful, device activated.

I just realized the connection ID is different. NM is automatically creating a new connection.
Even with the old profile (by nmcli con up and then start the software) the DNS severs are still not present in sd-resolved.

Last edited by Beemo (2026-01-09 22:56:25)

Beemo · 2026-01-09 22:46:27

seth wrote:

"nmcli device down ss-tun"?
Are you btw looking for https://archlinux.org/packages/extra/x8 … trongswan/ ?

Haha it's not really strongswan

Last edited by Beemo (2026-01-09 22:50:03)

Beemo · 2026-01-09 23:14:21

post split

Last edited by Beemo (2026-01-10 01:32:42)

Beemo · 2026-01-10 01:03:14

post split

Last edited by Beemo (2026-01-10 01:33:02)

Beemo · 2026-01-10 01:49:21

Seems like the choices are either fully managing an interface or not at all, and perhaps for a reason: https://unix.stackexchange.com/question … ap-devices

seth · 2026-01-10 10:06:47

it deactivates the connection too, and once the tun interface appears again the profile is not activated

I thought that was the plan?

I want the profile to activate / be applied when I run the software to create the tun interface, and deactivate when the software closes and removes the interface. However, currently NM creates a new interface when the original one is removed and stays up.

The idea would be to explicitly activate/deactivate the interface w/ whatever script you're running (sorry, thought "ss" would refer to strongswan)

Beemo · 2026-01-10 18:28:39

Originally I wanted the profile to deactivate when the interface disappears, like for a physical interface, but it creates a new tun interface instead.

seth wrote:

The idea would be to explicitly activate/deactivate the interface w/ whatever script you're running

Yea seems to be the way.

Lone_Wolf · Yesterday 21:06:59

Beemo, [Closed] is reserved for mods and indicates no more posts can be added to a thread.

Please use another term like [solved] and edit the title.

Arch Linux

#1 2026-01-09 22:05:06

[Solved] Make NetworkManager not create tun interface

#2 2026-01-09 22:25:13

Re: [Solved] Make NetworkManager not create tun interface

#3 2026-01-09 22:45:49

Re: [Solved] Make NetworkManager not create tun interface

#4 2026-01-09 22:46:27

Re: [Solved] Make NetworkManager not create tun interface

#5 2026-01-09 23:14:21

Re: [Solved] Make NetworkManager not create tun interface

#6 2026-01-10 01:03:14

Re: [Solved] Make NetworkManager not create tun interface

#7 2026-01-10 01:49:21

Re: [Solved] Make NetworkManager not create tun interface

#8 2026-01-10 10:06:47

Re: [Solved] Make NetworkManager not create tun interface

#9 2026-01-10 18:28:39

Re: [Solved] Make NetworkManager not create tun interface

#10 Yesterday 21:06:59

Re: [Solved] Make NetworkManager not create tun interface

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