Howto further debug when freeradius does not respond or log anything?

Gary Holtkamp dosenfleisch at
Wed Mar 4 17:27:37 CET 2015


I have a problem with a WLAN setup with freeradius 2.1.12 and a Cisco wireless LAN controller (WLC2504 version 7.6.120).
There is nothing special configured, just WPA2 Enterprise with certificates on the Windows machines.

It seems to me, that from time to time (happened 3x in the past 8 months or so ...) the Cisco WLAN controller sends
broken radius packages or something that freeradius doesn't like.

At first, I looked into the Cisco WLAN controller logfile, it logs something like "Radius server didn't answer request".

Next step was to restart freeradius manually on the console with the "-X" option to see what might be going on.
But freeradius didn't log anything. Next try was with "-X -x", but also no output there.

I then made sure with wireshark/tcpdump that the Cisco is really sending out radius packets and that they reach the freeradius server. They do and the packets look good in wireshark, nothing that is apparently broken with them. But freeradius is not sending out anything.

When I restart the Cisco, the problem goes away, so I'm quite sure that it's the Cisco that is sending broken
packets somehow.

Does anybody have an idea how to debug this further? I could ask Cisco, but they'll probably blame it on freeradius :-)

best regards,

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