Serial port sniffing?

[Richard Shaw]

I would like to monitor serial port communications read only, but I haven't
found a tool that makes that easy in the Fedora repos.

Anyone have suggestions?

Thanks,
Richard

[Samuel Sieb]

On 7/19/20 2:23 PM, Richard Shaw wrote:
>  I would like to monitor serial port communications read only, but I 
>  haven't found a tool that makes that easy in the Fedora repos. 
Are you just wanting to listen to what's coming in or do you want to 
intercept communication between a process and the serial port?

[Chris Adams]

Once upon a time, Richard Shaw <hobbes1069(a)gmail.com&gt; said:
>  I would like to monitor serial port communications read only, but I
> haven't
>  found a tool that makes that easy in the Fedora repos. 
You might look at an eBPF script - for example, there's a "ttysnoop" in
the bcc-tools package (it's /usr/share/bcc/tools/ttysnoop).  You might
be able to adapt that to your needs.
-- 
Chris Adams <linux(a)cmadams.net&gt;

[Ronaldo Mercado]

Hi,

Perhaps the script below works…

# set up the baud rate and no parity
stty -F /dev/ttyUSB0 9600 -parenb
# listen on TCP port 8001 and forward all traffic to the serial port
while [ 1 ] ; do nc -l $(hostname -i) 8001 </dev/ttyUSB0 >/dev/ttyUSB0; echo
reconnecting ...;  done

Then intercept all network traffic from port 8001 (tcpdump?)

Best wishes.


From: Richard Shaw <hobbes1069(a)gmail.com&gt;
Sent: 19 July 2020 22:23
To: Development discussions related to Fedora <devel(a)lists.fedoraproject.org&gt;
Subject: Serial port sniffing?

I would like to monitor serial port communications read only, but I haven't found a
tool that makes that easy in the Fedora repos.

Anyone have suggestions?

Thanks,
Richard

[Steven A. Falco]

On 7/19/20 5:23 PM, Richard Shaw wrote:
>  I would like to monitor serial port communications read only, but I
> haven't found a tool that makes that easy in the Fedora repos. 
I've done that with "socat" to monitor communications with an APC UPS.  Here
is my recipe:

socat /dev/ttyU3412A,raw,echo=0 \
SYSTEM:'tee in.txt |socat - "PTY,link=/tmp/ttyV0,raw,echo=0,waitslave" |tee
out.txt'

In the above, ttyU3412A is the physical serial port.  ttyV0 is created by socat, and that
is what you connect to.  All traffic gets logged to the two .txt files.

Please note that this is one long command line.  The SYSTEM thing is an argument to the
first socat.

	Steve