Configuration (Game.ini)

To configure your server-side settings, you will have to edit your game.ini file.
game.ini file location is different depends on your server operating system.

Linux:

Insurgency/Saved/Config/LinuxServer

Windows:

Insurgency/Saved/Config/WindowsServer

You can take a look at this configuration as an example:
https://github.com/zWolfi/INS_Sandstorm/tree/master/Insurgency/Saved/Config

To find more configuration, you can take a look at the dump:
https://github.com/zWolfi/INS_Sandstorm/tree/master/Dumps