Hi: I have a FreeRadius server setup that is used to authenticate a WPA2-Enteprise wireless network. This is setup on a CentOS 6.5 server with FreeRadius version 2.1.12. I also followed the instructions on configuring ActiveDirectory. Everything works, 99% of the time. However after a certain amount of time running I start to get authentication failures. The log shows: Wed Jan 29 11:30:31 2014 : Debug: [eap] processing type mschapv2 Wed Jan 29 11:30:31 2014 : Debug: [mschapv2] # Executing group from file /etc/raddb/sites-enabled/inner-tunnel Wed Jan 29 11:30:31 2014 : Debug: [mschapv2] +- entering group MS-CHAP {...} Wed Jan 29 11:30:31 2014 : Debug: [mschapv2] modsingle[authenticate]: calling mschap (rlm_mschap) for request 21 Wed Jan 29 11:30:31 2014 : Debug: [mschap] Creating challenge hash with username: vinoth Wed Jan 29 11:30:31 2014 : Debug: [mschap] Told to do MS-CHAPv2 for vinoth with NT-Password Wed Jan 29 11:30:31 2014 : Debug: [mschap] radius_xlat: Running registered xlat function of module mschap for string 'User-Name' Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: %{mschap:User-Name} -> vinoth Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: --username=%{%{mschap:User-Name}:-%{%{User-Name}:-None}} -> --username=vinoth Wed Jan 29 11:30:31 2014 : Debug: [mschap] radius_xlat: Running registered xlat function of module mschap for string 'NT-Domain' Wed Jan 29 11:30:31 2014 : Debug: [mschap] No NT-Domain was found in the User-Name. Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: %{mschap:NT-Domain} -> Wed Jan 29 11:30:31 2014 : Debug: [mschap] ... expanding second conditional Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: --domain=%{%{mschap:NT-Domain}:-CLAIRMAIL} -> --domain=CLAIRMAIL Wed Jan 29 11:30:31 2014 : Debug: [mschap] radius_xlat: Running registered xlat function of module mschap for string 'Challenge' Wed Jan 29 11:30:31 2014 : Debug: [mschap] Creating challenge hash with username: vinoth Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: %{mschap:Challenge} -> 26bae25103c92b9d Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: --challenge=%{%{mschap:Challenge}:-00} -> --challenge=26bae25103c92b9d Wed Jan 29 11:30:31 2014 : Debug: [mschap] radius_xlat: Running registered xlat function of module mschap for string 'NT-Response' Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: %{mschap:NT-Response} -> bc3ebc2680d1a09bd8f20d10586071f40fa03830ca779b81 Wed Jan 29 11:30:31 2014 : Debug: [mschap] expand: --nt-response=%{%{mschap:NT-Response}:-00} -> --nt-response=bc3ebc2680d1a09bd8f20d10586071f40fa03830ca779b81 Wed Jan 29 11:30:31 2014 : Debug: [mschap] External script failed. Wed Jan 29 11:30:31 2014 : Debug: [mschap] FAILED: MS-CHAP2-Response is incorrect The issue is resolved by simply restarting FreeRadius. Any help on further troubleshooting would be appreciated. Thanks