Alfred Reynolds, from Valve has Relased the 1st look at the "Source RCON format" to the [hlcoders] mail list, this is the first look at Source Code - not much to those not into code, but a big leap, to the SDK, and Source System going live!
Here is a snip of the email - and the whole quote can be found at Ammahls.com
Here is my first pass at writing a spec for the RCON format, feel free to ask questions.
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Source Server RCON formatThe protocol is based around command/response packets encapsulated in a TCP/IP stream. The stream can have multiple outstanding commands and can be extended to allow for multiple sub-channels of data.
The command packet format consists of:
packet size (int)
request id (int)
command (int)
string1 (null delimited string)
string2 (null delimited string)
amckern