So I’m working on a server from home.
I do a cat /sys/class/net/eth0/operstate and it says unknown despite the interface being obviously up, since I’m SSH’ing into the box.
I try to explicitely set the interface up to force the status to say up with ip link set eth0 up. No joy, still unknown.
Hmm… maybe I should bring it down and back up.
So I do ip link set eth0 down and… I drive 15 miles to work to do the corresponding ip link set eth0 up
50 years using Unix and I’m still doing this… 😥


At $DAYJOB, we’re currently setting up basically a way to bridge an interface over the internet, so it transports everything that enters on an interface across the aether. Well, and you already guessed it, I accidentally configured it for
eth0and couldn’t SSH in anymore.Where it becomes fun, is that I actually was at work. I was setting it up on two raspis, which were connected to a router, everything placed right next to me. So, I figured, I’d just hook up another Ethernet cable, pick out the IP from the router’s management interface and SSH in that way.
Except I couldn’t reach the management interface anymore. Nothing in that network would respond.
Eventually, I saw that the router’s activity lights were blinking like Christmas decoration. I’m guessing, I had built a loop and therefore something akin to a broadcast storm was overloading the router. Thankfully, the solution was then relatively straightforward, in that I had to unplug one of the raspis, SSH in via the second port, nuke our configuration and then repeat for the other raspi.