Serious noob, here. That being said, I wasn't messing around with the OS--at least not directly. I am setting up an openHAB system and tried to enable wireless via the openhabian-config utility. Well that didn't work because it never connected with the router. Unfortunately, the wired interface stopped working, too. Re-disabling wireless did not return wired to an operational state. I posted this problem on the openHAB forum since it was caused by an openHAB utility, but one of the regulars on the forum basically told me to "get lost, take your problem to a Raspberry Pi forum." So here I am. This is a new system, so it's running the latest rev of everything. What I *do* know:
I can get the interface up after booting by issuing a "dhcpcd eth0 up" (no idea if that's even the right/accepted way, but it works and I found it by accident...)
After reboot, the interface is down again until I issue the dhcpcd command again.
When I do issue that command it complains that eth0 is invalid before "forking to the background" whereupon the interface comes up and starts working. It complaining tells me I'm doing *something* wrong, but it still works anyway.
I need help getting it to come up normally by itself after a reboot.