I'm trying to diagnose some connection issues I was having last night while setting up my new PC based router.
For a while everything was working perfectly, but then suddenly I found that I couldn't ping the new PC, and I couldn't ping other machines from that PC. Eventually I set wireshark up collecting on my machine and pinged that machine from the new PC. I saw the ping requests reach my machine and the response sent, but I still saw nothing on the new PC. (which is running an embedded version of pfSense - a FreeBSD distribution)
Thinking back the only possibility I can see is that it's something to do with the fact I kept on giving the new PC the same IP address as our existing router, (192.168.1.1) and assigning the old router another IP address (192.168.1.42). I ended up doing this a couple of times and never restarted my main PC, so I wondered if the ARP tables got messed up somehow.
So, what happens to packets where the IP address matches, but the MAC address does not (or the other way around)? Are they just ignored?
Also, are there any more diagnosis tools or methods I can use? (other than just turning different things on and off again...)