I am setting up Debian computers for my high school and I would like to somehow customize LightDM to display system and network information at the login screen.
The big picture is the following : people log into the computers thanks to LDAP authentication. But we have a non-optimal network situation.
First, the computer could be physically disconnected from the network. Second, the DHCP server could fail to give the computer an IP address in time. Third, the LDAP server might be down.
Currently, the standard way to detect this is that your login credentials are rejected. But then you might as well have mistyped them, or simply forgot them.
So there are various causes for a failure to log in, and we unfortunately cannot expect most teachers to even begin to understand them, which leads to frustration and low-value reports of "I cannot login".
So I would like to display an information window stating either "Network cable seems to be disconnected" or "Network is responding, waiting for an IP address" or "Network seems down" or "Network is ready for authentication".
How can I run a program that would compute such information, then display and maybe update it on the login screen ?