In the last post, I told you about the extra code I found in the router software. It was a bit strange for it to be there, because it didn't really seem to have any purpose.
I had some testing software that could simulate being a router. This software would act like the router, but you could step through the whole process one step at a time, watching the software router analyze data packets.
I used this software with some packets I had captured with a network sniffer. A sniffer copies data packets to a file for later analysis. While working on many different systems, I had collected many MB of data packets in many different files. Usually, I didn't look at all the packets from the sniffers. When using sniffers, you would typically gather lots of data, and then look at different parts of the saved data. You'd never have to look at all the data; that would take too long. You'd just jump around in the data looking for misrouted stuff. You would ignore the 'good' data packets. Over the course of many 'sniffing expeditions', I had collected many megabytes of data packets stored in files here and there.
Most of these data packets were stored on various company systems that I had been working on. These systems had gigabytes of data storage, so it was not a problem to leave the packet data files on those systems. Usually, I'd just forget about the sniffer data that I had stored, so it was still there.
To analyze the packets from the various sniffers, I had to gather it into one place. I needed to get the data to one of my test systems. And it also looked like I would have to get some "fresh" data packets from some other systems.