Edge case: TLS failure

[East, Bill]

I feel I should put this out there just in case someone else does something as unusual as this:

This morning, one of my staff members reported that her PC, which we're testing 802.1x authentication on, was dropping off the network. I thought to check the logfile and found

Wed May 11 10:09:38 2011 : Error: TLS Alert write:fatal:bad record mac
Wed May 11 10:09:38 2011 : Error: rlm_eap: SSL error error:1408F119:SSL routines:SSL3_GET_RECORD:decryption failed or bad record mac
Wed May 11 10:09:38 2011 : Error: SSL: SSL_read failed in a system call (-1), TLS session fails.

Googling came up with a lot of hits from this list, but none of the cases seemed to fit exactly. I restarted the daemon to see if there was a problem there but the error came back again. Finally since this seemed to be limited to the one machine alone I did some digging into the environment. Turns out, this is a newish machine, and the old one is still on the network and running. Further, she had just set a reservation for the new PC in DHCP, to use the old one's address. The old one, though, still had the old address. So we had two machines on a single switch port (using a dumb mini-switch), both with the same IP. We reassigned the old PC's IP and haven't seen a problem since.

Amazing what can happen when you really screw up your environment.


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