Source RCON Protocol Info

TCP Packet Structure Field Type Value Python_Representation Size 32-bit little-endian Signed Integer 'i<' ID 32-bit little-endian Signed Integer '<i' Type 32-bit little-endian Signed Integer '<i' Body Null-terminated ASCII String Varies "string\x00" Empty String Null-terminated ASCII String 0x00 '\x00'

https://developer.valvesoftware.com/wiki/Source_RCON_Protocol