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Plug In an Ethernet Cable, Take Your Datacenter Offline
New submitter jddj writes: The Next Web reports on a hilarious design failure built into Cisco's 3650 and 3850 Series switches, which TNW terms "A Network Engineer's Worst Nightmare". By plugging in a hooded Ethernet cable, you...well, you'll just have to see the picture and laugh. They write: "The cables, which are sometimes accidentally used in datacenters, feature a protective boot that sticks out over the top to ensure the release tab isn’t accidentally pressed or broken off, rendering the cable useless. That boot would hit the reset button which happened to be positioned directly above port one of the Cisco switch, which causes the device to quietly reset to factory settings."
The mode button triggers "express setup" which is basically a lazy way to configure the shit for retard small business/enterprise admins so they don't have to console the device via rs232 to configure it.
For which model? In every Cisco device I've used (including the C3560 switches I own for CCIE training) the mode button only does anything at all if you have it held down while the switch is powering on. Doing so goes into ROMMON, which allows you to change the configuration register to ignore the startup-config.text file on the flash (the startup-config.text file is what contains all of the password information, so if it doesn't execute, then you effectively have a factory configuration switch, although your configuration files are still present if you need to use them.)
By the way, you can also modify the configuration register so that if the mode button is held at bootup, then it simply wipes the configuration files entirely, that way you don't have to worry about somebody stealing your configuration data if you have a switch that's in a geographic location that you can't reasonably have physically secured.
If I'm remembering correctly...
If there's a TFTP server properly configured... If there's bootp on the LAN properly configured... If there's a switch configuration saved to that TFTP server and If it's named correctly such that there's a mechanism for associating it with a given request, some Cisco equipment can autoconfigure by pulling the config down off of TFTP without administrator intervention. I've seen some C2960S and C3560G do this; had to clear-out, IOS update, and put config templates on about 160 switches over a few days, watching it complain about not being able to find a TFTP server is just a little burned into my brain.
No one that I've spoken with has ever used this feature in production, and honestly it would take so much advance-setup to make it work that no boss would choose that path out of laziness instead of getting out a console cable, but technically if the switch were reset with the mode button it might make the attempt.
Again, if I'm remembering correctly.
I wish that Cisco would make it harder to press that button. Some older switches were REALLY bad, the button was the whole left end of the panel. If the closet is racked incorrectly the component above or below the switch could press the button and hold it down. I've seen it happen a few times.
Do not look into laser with remaining eye.