[Solved] NetworkManager/dispatcher.d scripts not being executed for wlan up/down

[seberoon]

[I first posted essentially this question in the RPi Troubleshooting forum, but no takers. I have now tried exactly the same thing in a fresh install of stock Debian 12 on a separate machine. Same behaviour, so this doesn't seem to be RPi-specific. I'm hoping that one of the Debian network gurus will be able to set me straight. For context, I have not made any changes to the network configuration beyond plugging in a wifi dongle and using the Gnome widget to connect to my home wifi. The wlan interface name below is the one that was chosen automagically.]

I have a script that I want to be executed when the wireless lan interface is taken down. I have tried both the following: a) place a script in /etc/network/if-down.d; b) place a script in /etc/NetworkManager/dispatcher.d. As far as I can tell, a) has no effect (the script is never run). For b) the script is run sometimes, but not when the wlan interface is taken down. For debugging purposes I have this:

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> cat /etc/NetworkManager/dispatcher.d/00-log-iface-events.sh
#!/usr/bin/env bash
interface=$1
event=$2
echo "===========" >> /tmp/Hello-there.txt
echo "$interface received $event" >> /tmp/Hello-there.txt

Having checked that wlx7cdd905b9c3d is up, I do

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sudo ip link set wlx7cdd905b9c3d down

Nothing is written to the tmp file at all.
I then do

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sudo ip link set wlx7cdd905b9c3d up

The following is written:

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===========
wlx7cdd905b9c3d received dhcp4-change
===========
wlx7cdd905b9c3d received dhcp6-change

Note that only the dhcp events are logged, no "up" event.

One additional data point: if I reboot with that script in place in /etc/NetworkManager/dispatcher.d, an "up" event is logged in the tmp file, so it seems that things do behave the way I was expecting when the wlan is first brought up.

Any ideas?

[Aki]

Hello,

What is the content of the file named /etc/network/interfaces ? You can use the following command:

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cat /etc/network/interfaces

Just a guess. Try the following command:

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sudo ifdown wlan0

Then check the output of tmp file generated by the script in /etc/network/if-down.d

[seberoon]

[Note: the actual wlan interface name is wlx7cdd905b9c3d not wlan0. Ugh. Where I wrote wlan0 in my original post it was a copy-paste error from my earlier RPi forum post.]

@Aki It looks like ifupdown cannot be used to manage interfaces used in the default Debian 12 network set up:

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> cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

(/etc/network/interfaces.d is empty).
So:

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> ifdown wlx7cdd905b9c3d
ifdown: unknown interface wlx7cdd905b9c3d

From a bit of Googling it seems that I need to use the ip command and NetworkManager is (mostly?) in charge of things.

[Aki]

Hello,

Can you please check if the network manager is running ? You can use the following commands:

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ps aux | grep /usr/sbin/NetworkManager
nmcli networking
nmcli device

You can check the permission for your script with the command:

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ls -la /etc/NetworkManager/dispatcher.d/*

You can disable and re-enable your network interface to verify if the script in /etc/NetworkManager/dispatcher.d/ is triggered:

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sudo nmcli device down wlx7cdd905b9c3d
sudo nmcli device upwlx7cdd905b9c3d

[seberoon]

@Aki Hi, yes, it is running. Note from my original post that the script in /etc/NetworkManager/dispatcher.d is being executed for dhcp status changes (those that are triggered after the wlan interface comes up). My issue is specifically that the script doesn't get called in response to the wlan going up or down.

PS I think I have found a workaround/solution: use wpa_cli with an action script. Will post a follow-up once I am sure.

[lindi]

Your service might have a private /tmp, try writing to some other location or strace the nm execution

[seberoon]

I found a way using wpa_cli, as described in this old stack exchange post, for example: https://unix.stackexchange.com/question ... aemon-mode. To test, I placed a test script in /etc (it doesn't work if the script is in /root, as I eventually realised after much cursing that wasn't the issue: make sure to specify the full path for your action script file - a local path only works if you are not running wpa_cli as a daemon):

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> cat /etc/wpa-action.sh 
#!/usr/bin/bash

interface=$1
event=$2

echo "=========== wpa_cli action =====" >> /tmp/Hello-there.txt
echo "$interface received $event" >> /tmp/Hello-there.txt
echo "WPA_CTRL_DIR: $WPA_CTRL_DIR" >> /tmp/Hello-there.txt
echo "WPA_ID: $WPA_ID" >> /tmp/Hello-there.txt
echo "WPA_ID_STR: $WPA_ID_STR" >> /tmp/Hello-there.txt

Then execute:

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wpa_cli -a /etc/wpa-action.sh -B

Now when I bring the wlan up and down, the script gets run and I see the following kind of thing in the tmp file:

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=========== wpa_cli action =====
wlx7cdd905b9c3d received DISCONNECTED
WPA_CTRL_DIR: /var/run/wpa_supplicant
WPA_ID: 0 
WPA_ID_STR:  
=========== wpa_cli action =====
wlx7cdd905b9c3d received CONNECTED
WPA_CTRL_DIR: /var/run/wpa_supplicant
WPA_ID: 0
WPA_ID_STR: 

[seberoon]

PS How do I mark as solved? Sorry, figured it out.