Hi all, I am receiving hundreds of INVITE/minute and in the log I can see: /2014-06-04 13:52:30.189371 [WARNING] sofia_reg.c:1532 SIP auth challenge (REGISTER) on sofia profile 'internal' for [340@MyExternalIP] from ip 62.210.142.39// //2014-06-04 13:52:42.789530 [WARNING] sofia_reg.c:1532 SIP auth challenge (REGISTER) on sofia profile 'internal' for [341@MyExternalIP] from ip 62.210.142.39// //2014-06-04 13:52:55.479999 [WARNING] sofia_reg.c:1532 SIP auth challenge (REGISTER) on sofia profile 'internal' for [341@MyExternalIP] from ip 62.210.142.39// //2014-06-04 13:53:08.289660 [WARNING] sofia_reg.c:1532 SIP auth challenge (REGISTER) on sofia profile 'internal' for [342@MyExternalIP] from ip 62.210.142.39// //2014-06-04 13:53:21.679512 [WARNING] sofia_reg.c:1532 SIP auth challenge (REGISTER) on sofia profile 'internal' for [342@MyExternalIP] from ip 62.210.142.39/ In the /etc/fail2ban/filter.d/freeswitch.conf file I have these lines: /failregex = \[WARNING\] sofia_reg.c:\d+ SIP auth failure \(REGISTER\) on sofia profile \'\w+\' for \[.*\] from ip <HOST> \[WARNING\] sofia_reg.c:\d+ SIP auth failure \(INVITE\) on sofia profile \'\w+\' for \[.*\] from ip <HOST>/ You can see clearly that my logs contain failure word not "auth challange". My question is : If I put "auth challange" in my /etc/fail2ban/filter.d/freeswitch.conf will I block regular known and authenticated SIP clients ? If yes, could you help find the right regex to stop this kind of spammers ? Thank you very much in advance.