So, I finally got this project (PiAlert) working how I'd like.
It basically uses arp to keep track of devices on your network, and let you know when new ones join. It gives some basic stats like uptime, etc and you can configure a few different notification options to be alerted when a rogue device connects.
Anyways, to get this work on my network involved setting up several network interfaces, as I have quite a few VLANs I'd like to keep an eye on. While everything seems to be working, I feel like I may have created an asymmetric-routing situation, as now when I SSH to the VM hosting this, it will freeze up after a few seconds.
My interfaces look like such. The problem is that I am accessing this VM (hosted on 192.168.1.0/24) from my personal network (192.168.6.0/24). My personal network has access to 192.168.1.0/24 and obviously to it's own subnet, so I think packets are getting confused, as there are multiple routes they can take to this VM.
I believe this is confirmed, because if I disable the entry for 192.168.6.0/24 in my /etc/network/interfaces file, the problem goes away.
How should I handle this? I've tried some simple UFW rules to try to force things to only use the 192.168.1.0/24 interface, but to no avail.
Edit: Sorry for the weird markdown, not sure why it's highlighting keywords
Would that be similar to telling SSH to listen on only one interface? Because I did try that but it unfortunately did not resolve the issue
Edit: Found what you mean. I'll give this a try, thanks!
Not quite. Static route is coded on both ends. Tells your machines 'if you want to talk to network B use this ip / route and no other.' And then on the other end tell the machine 'you want to talk to network A via this ip/route and no other.'
You can jigger with the subnets obvs, to cover an entire network range or just a specific ip / machine