nm-toggle

The purpose of this tool is to be able to, through NetworkManager, completely shutdown all network devices — and bring them back up when needed. I use ArchLinux with the i3 window manager, so the program is somewhat tied to them (particularly concerning systemd, and the shell, bash in my case).

(If you are wondering why would I want to toggle between on and offline like this, instead of being always online, it is because the internet is transformed into a gigantic weapon of mass distraction, being on the cross-hairs of which I usually prefer to avoid.)

How it works

Needed packages:

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# pacman -S networkmanager
# pacman -S network-manager-applet

The source consists of a a C source file, which produces an executable named nm-toggle. It takes two arguments on|off, the latter being the default (for when either no argument is provided, or an invalid argument is provided). For off, it disables wired and wireless interfaces, stops NetworkManager, and then masks its service files. This is to prevent it going up in the next reboot. For on, it does the opposite: unmask, start NetworkManager, and enable wired and wireless interfaces.

The executable should be stored in /usr/local/bin, which is virtually always a) on $PATH (put it there if it’s not); and b) only writable by root. It only takes two short arguments – so I allow it to run with password-less sudo privileges. If a remote attacker gains non-root access to my machine, this program only buys him the possibility of closing the network, which doesn’t really help his case… (if he gains root access, I am toast anyway, sudo privileges or not).

For convenience, two .bashrc alias are provided (see below), and a systemd service file to ensure NetworkManager will not be automagically brought up in the next reboot.

Setup

  1. Setup/install sudo if you don’t have it already.

  2. Run $ make.

  3. $ sudo cp nm-toggle /usr/local/bin

  4. Run visudo and write this line:

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your_username ALL=(ALL) NOPASSWD: /usr/local/bin/nm-toggle

If your default editor is vi(m), save and exit by hitting <Esc>:wq<Enter>. Now the command can be run without requiring a password.

  1. The following aliases might come useful (bash only, sorry!):
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alias online="sudo /usr/local/bin/nm-toggle on"
alias offline="sudo /usr/local/bin/nm-toggle off"

Remember to source .bashrc before using it.

  1. To avoid NetworkManager automagically starting up on the next reboot, put the NetworkManager-stop-n-mask.service file in /usr/lib/systemd/system, and then do:
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systemctl enable NetworkManager-stop-n-mask.service

You can additionally also do start (after doing enable) to test the service — NetworkManager should be totally brought down.

Now at a terminal, just type offline to kill all connectivity. $ online brings everything back up. Note that it may take a few seconds for a wireless link to be (re-)established (ethernet is usually near-instantaneous).

And that’s it. Enjoy the minimisation of your online time!

github repo

https://github.com/notnotrandom/nm-toggle