Detect if current connection is metered with NetworkManager

Question

How can I detect whether the current connection is marked as metered on a system with NetworkManager?

This is from a shell script, but I can easily call any C functions via Python.

Armillary

Answer 1

With the nmcli utility, the necessary steps are:

1. verify NetworkManager is version 1.0.6+:

   $ nmcli -v nmcli tool, version 1.9.0

2. check GENERAL.METERED on an interface:

   $ nmcli -t -f GENERAL.METERED dev show eth1 GENERAL.METERED:unknown

3. values are: unknown, yes, no, yes (guessed), no (guessed)

4. Forcing the value is done like this:

   $ nmcli dev modify wlan1 connection.METERED yes Connection successfully reapplied to device 'wlan1' $ nmcli -t -f GENERAL.METERED dev show wlan1 GENERAL.METERED:yes

And, to get a list grouped by device:

  $ nmcli -t -f GENERAL.DEVICE,GENERAL.METERED dev show

  GENERAL.DEVICE:wlan1
  GENERAL.METERED:yes

  GENERAL.DEVICE:eth1
  GENERAL.METERED:unknown

  GENERAL.DEVICE:lo
  GENERAL.METERED:unknown

Trying to cut this down to info on just the default route would still require a call to another command as NetworkManager doesn't try to distinguish between multiple devices in a connected state:

  $ nmcli -t -f GENERAL.DEVICE,GENERAL.METERED dev show `ip route list 0/0 | sed -r 's/.*dev (\S*).*/\1/g'`

Intoxication

Excellent! Is there a way to only show the information for the network the first default route is going over? With many VPNs and otherwise virtual networks, the output of nmcli -t -f GENERAL.METERED dev show (without a device) is a mixture of all possible values for me. – Armillary

I've added a way to see the device names, but I think you may need to ask ip route and ideally ip monitor to reliably track the interface of the default route or relevant server then do/redo the nmcli query. – Intoxication

Thanks! I'll award the bounty in a couple of hours. – Armillary

See also unix.stackexchange.com/questions/364927/…, which describes how to set the connection (i.e. SSID) rather than the interface. This makes sense when you may have more than wifi connection, one to a mobile hotspot. – Rival

You can test the output with [[ "$(nmcli -t -f GENERAL.METERED dev show `ip route list 0/0 | sed -r 's/.*dev (\S*).*/\1/g'` | cut -d':' -f2)" == yes* ]] – Northampton

Answer 2

You can also get the metered status of the current connection via D-Bus. From a shell, you can use busctl:

busctl get-property org.freedesktop.NetworkManager /org/freedesktop/NetworkManager org.freedesktop.NetworkManager Metered

which is only one command, in contrast to the nmcli solution, and in other programming languages it can be more efficient to use D-Bus directly instead of having to call nmcli.

The result is an enum with the following values (documentation):

Name	Value	Description
NM_METERED_UNKNOWN	0	The metered status is unknown
NM_METERED_YES	1	Metered, the value was explicitly configured
NM_METERED_NO	2	Not metered, the value was explicitly configured
NM_METERED_GUESS_YES	3	Metered, the value was guessed
NM_METERED_GUESS_NO	4	Not metered, the value was guessed

Nelda

The result is an enum with the following values – Northampton

The output is something like: u 1 . If you prefer JSON, then pass the -j flag, and you will get output like { "type": "u", "data": 1 } – Louisiana

For future explorers, you can use Gnome's D-Spy app to explore and get the service, object, interface, and property names passed to busctl. It even tells you the datatype and lets you query the property in real-time. Invaluable! – Platonic

Answer 3

For some reason the solution from lossleader always returns no on my system, while using the metered parameter from the connection works fine:

nmcli -f connection.metered connection show `nmcli -t -f GENERAL.CONNECTION --mode tabular device show $DEVICE | head -n1`

Edlin