16 bit checksums

[fathernitwit]

Hello,

im new around here, just found out about eqemu about 2 days ago, but I am very excited about it... anyways... I am a decently skilled network programmer, I have about 5 years of protocol development experience.

I have been reading about the login server problems, and am trying to analyze the protocol... One thing I am running into is once the login process gets started, they start appending 16 bit checksums to the end of the packets.

I am unable to figure out how this checksum is computed... The only 16 bit checksum I am framiliar with is crc16, and beings that they use crc32 for their normal packets, I gave it a try... but it isnt giving me anything... I am using CalcCRC16Bytes (from http://www.indigosystems.com/CServices/crc16_c.html). I have tried it both including the trailing 2 bytes as 0's as well as excluding the trailing 2 bytes...

Is anybody framiliar with any other 16 bit checksums, a different implementation of crc16 for bytes, or might offer other insight as to how they might be computing this checksum?

two example packets, in hex:
00 15 00 01 a9 bf
00 15 00 02 f8 05

I belive that the last 2 bytes of each line are the checksum.. I dont know what else it could be.