If you’ve got a screen flicker that looks similar to a Gaussian blur but you’re on an LCD monitor, chances are you’ve got yourself a ground loop. The easy way to find this out is to do a search on Google for “flickering LCD monitor.” The Noah way is with a multimeter and an hour of time that I could have spent doing other things *facepalm*.
It should also be noted if you get a low frequency buzz or whine out of your headphones when you’re connected to your computer’s audio jack this would be caused by the same thing.
You fix this by having your monitor and computer plugged into different power outlets or by removing the ground plug off one of the devices.
I’m having an issue with this server I recently setup that is driving me nuts. I have a dual-homed system (no real bastion config, just LAN separation) – eth0 is the internal network, eth1 is the link to the outside world connected through the firewall DMZ. eth1 has an unroutable IP (172.20.x.x) linked to a valid public IP via firewall. The issue is that eth1 goes unresponsive while eth0 is up. Looking at it from the server, all traffic goes to one NIC or the other so that makes sense.
The easy fix is to specify metrics for eth0 and eth1, but then that prioritizes all traffic to one NIC or the other. I could specify routes through ifconfig…there aren’t many so that’s doable. The other solution I see would of course be to set up routes in the firewall that map to each NIC and be done with it that way. What do you guys think? Is there an elegant solution here that I’m missing?