Linux Fu: Eavesdropping On Serial

Arthur T Knackerbracket has processed the following story:

In the old days, if you wanted to snoop on a piece of serial gear, you probably had a serial monitor or, perhaps, an attachment for your scope or logic analyzer. Today, you can get cheap logic analyzers that can do the job, but what if you want a software-only solution? Recently, I needed to do a little debugging on a USB serial port and, of course, there isn't really anywhere to easily tie in a monitor or a logic analyzer. So I started looking for an alternate solution.

If you recall, in a previous Linux Fu we talked about pseudoterminals which look like serial ports but actually talk to a piece of software. That might make you think: why not put a piece of monitor software between the serial port and a pty? Why not, indeed? That's such a good idea that it has already been done. When it works, it works well. The only issue is, of course, that it doesn't always work.

The software in question is interceptty. You may have to build it from source, but there aren't any oddball dependencies. [...]

[...] The software uses the concept of a backend device and a frontend device. The back device is, usually, your normal serial port. The frontend device is something that interceptty creates. So the idea is that you connect the program to the backend, it creates the front end, and then you connect some other program to the front end. The program will log all the traffic between the program connected to the front end and the port on the back end.

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