modify a datastream on the fly

Question

I need to hijack and modify a datastream. The stream consists of fixed-width commands. Each command is a new line, and the documentation says that each command starts and ends

Answer 1

Yes, the iPocket does raw pass-through of the data. The options are typically for packetization of the incoming data which won't actually affect what you're trying to do here. (I wrote the firmware for that device.)

However, none of the command-line answers here will work because they are line-based and your data is not. That is to say, there are to linefeeds in the data stream that sed and perl use as "packet" boundaries.

I don't believe there is any way you're going to be able to accomplish this from the command-line. You're going to have to write a simple program that reads an incoming TCP stream, looks for the STX/ETX framing, replaces the characters as you wish, and then writes the data out the other side. (Don't forget pass-through the back direction, too.)

Python is probably the simplest way to do this.