Here's the word from Counter-Server, from Erik Johnson, from Valve (whew!) concerning the new speed cheat server-side patch:
No word yet if this is wholly effective, so all server admins hit the FTP and download the new patch. Please send all bug reports/patch issues to Eric Smith at Valve.We've posted a beta version of the Half-Life server that addresses the
current Windows 95/98/ME clock speed cheat. If a person is using the
speed cheat you will see a message in the server console like this:
Dropped from server
Reason: User has corrupt system clock
We want to make sure this doesn't affect any legitimate players, so
please report any issues to Eric Smith (erics@valvesoftware.com).
The only changed file for this release is the sw.dll (for Win32) and
engine_i386.so (for Linux). Make sure to make backup copies of the
current file on your server before installing the new beta.
The md5sum for the Linux server is 24e82c7d958f7af11c213718fb92a02d
FTP Site Information:
ftp : ftp.valvesoftware.com
login : hlserver
password : testserver