From: thefed <fedzor@...>
Date: 2007-11-29T07:38:07+09:00
Subject: Custom Protocol

I understand that I've asked a similar question that of custom packets.
But this is different. This is __protocol__.

Has anyone constructed a custom protocol, such as UDT, in Ruby?
What would one use to construct a custom protocol?

Right now, I'm using code from metasploit 3.0 (written in Ruby :-), and
the CStruct2 library included. Some sample stuff I have...

UDT_CTRL_PKT = Rex::Struct2::CStructTemplate.new(
	[ 'uint1v',  'PktType',           0 ],
	[ 'uint8v',  'Type',              0 ],
	[ 'uint16v', 'ExtType',           0 ],
	[ 'uint1',   'X',                 0 ],
	[ 'uint30v', 'SubSeqNum',         0 ],
	[ 'uint32v', 'TimeStamp',         0 ]
)



UDT_DATA_PKT = Rex::Struct2::CStructTemplate.new(
	[ 'uint1v',   'PktType',             0 ],
	[ 'uint30v',  'SeqNum',              0 ],
	[ 'uint2v',   'FF',                  0 ],
	[ 'uint1v',   'O',                   0 ],
	[ 'uint28v',  'MsgNum',              0 ],
	[ 'uint32v',  'TimeStamp',           0 ]
)

What I'm intending to do - what you're **supposed** to do - with the
CStruct2 lib is to create  a binary string out of it and write that  
to a raw socket.

What are some techniques someone would use to accomplish the goal of a
new protocol?

Thanks,
Ari Brown