netch
netch is a utility for monitoring a system's internet connection status (not just whether or not it has an IP)
netch checks the internet connection by attempting to SSH to a known host and verifying that the SHA1* digest of the host key received matches a known-good value. It is best used on Debian-based systems in conjunction with scripts in if-down.d and if-up.d. In this scenario, the up and down scripts notify netch when the interface is up in order to minimize unnecessary checks.
* limited to SHA1 or MD5 by libssh2
Requirements
- libconfig (on Ubuntu systems install the libconfig++8-dev package)
- Python
- python-libconfig (currently at http://github.com/azeey/python-libconfig)
- libssh2 (libssh2-1 on Ubuntu)
- pylibssh2 (python-libssh2 on Ubuntu)
Setup
- mkdir ~/.config/netch
- mkdir ~/.config/netch/hooks
- copy config.sample to ~/.config/netch/config
- edit ~/.config/netch/config and define at least one host
Configuration
See config.sample for a full list of config options. At a minimum you will need to define one host (as shown in config.sample) and set the following options:
- check_when_online: whether or not to repeatedly checking the connection status when online
- online_hook: list of commands to run after coming online
- offline_hook: list of commands to run after going offline
Signals
- SIGUSR1: signal interface down, causing netch to pause connection checks
- SIGUSR2: signal interface up, causing netch to reset the connection status and resume checks
- SIGHUP: reload the config file
License
netch is available under the GNU General Public License v2, or (at your option) any later version.