HL1 Engine
- Fixed several exploits triggered by malicious server operators (found by Stan Bubrouski)
- As part of the next version of VAC, which is currently in testing, the Linux game server now must have GLIBC 2.3.2 or above installed

HL1 Engine Master Server Query Protocol
/These changes bring the HL1 engine's querying protocol in line with that of the Source engine. If you connect to Steam enabled game servers using a third party tool, you may need to contact the vendor for an update/
- Added a challenge number to A2S_PLAYER and A2S_RULES server queries.
- Setting "sv_enableoldqueries" to 1 (currently the default) allows old style (no challenge/response) queries to work
- Changed A2S_INFO server query to require the string "Source Engine Query" appended to the end of the query packet
- Removed support for "info", "infostring", "details", "players" and "rules" queries, use A2S_INFO, A2S_PLAYERS and A2S_RULES instead