Summary
HLGuard is a server-side anti-cheat system for Half-Life and it's many modifications. Originally developed under the name CSGuard by OLO before moving to United Admins Limited who adapted it for use with all Half-Life modifications, the project has now been given a new home at The Z Project who plan to further develop it's features and introduce new detection methods.
Features include

•  Aimbot detection
•  Wallhack blocking
•  Client file enforcement (including models, sounds, etc)
•  Alias detection
•  Cvar enforcement
•  Name banning
•  Built-in Steambans client

The list goes on. It also provides a customisable output for logs, so you can output in any format you want, this can be useful for displaying caught cheaters on your website.

HLGuard 1.8 - Download