TF2 console command

[sunw]

Hi, I have made a TF2 server by installing the "Team Fortress 2 Dedicated Server" application through Valve. I've set it up and got a server running that people can connect to, and I've been managing server options by using console commands through the admin console window. I just don't know how to disable auto-kick on afk players. What is the Valve console command to disable the auto drop or disconnection of afk'ers?

Thanks for your help. This is really bugging me.