22 Aug
2005
22 Aug
'05
2:25 p.m.
On 8/22/05, Dwight K. Elvey <dwight.elvey at amd.com> wrote:
Hi
I've cracked other protocols by connecting another
computer up to monitor the traffic on the serial lines.
I don't think they did anything fancy. Probably the toughest
thing might be determining the CRC,ECC or checksum method
that they use. It would be best if you could simultaneously
monitor both directions with two serial ports but
I just did one direction at a time and then experimented
until I got all the handshake.
You, of course only want to use the input of the monitoring
computer. You could make a snooping connector or as I did.
I just used two easy clips on the exposed connector.
Dwight
Yes, if I can't find any info (which it looks like is going to be the
case) I will have to reverse engineer it.
The protocol sniffer I use is "snooper" from debian... it uses two
real serial ports and bridges them through software while showing the
traffic in hex on-screen. It also shows the flow control lines. Of
course clipping onto the leads as you did will give more accurate
results, but if the protocol is largely request/response oriented a
man-in-the-middle type snooper should be good-enough.
What I expect to see is a lean packet around a serialized form of DOS
software interrupts. But I don't know all that much about DOS so I
don't know yet how the redirector works but I suspect that is the key
concept to understand.
Aside from the data protocol, possibly the flow control lines may be
used for something when present.
Anyway, just have to get out the tools :-)
Thanks,
-- John.