Left4Dead 2 server - stop access from matchmaking games?

[ubermensch]

Haven't run a Left4Dead 2 server for what must be a year or so now, and I'm wondering how I can stop my server from being used in matchmaking games?

Thanks

[Chartax]

You could force it to be exclusive to a steamgroup, if you'd prefer, with the use of sv_steamgroup and sv_steamgroup_exclusive 1

[CentralFrag]

Chartax is right. sv_password doesn't work quite as you expect it. I'd say your best bet would be to make it a steam group only server.