Unauthorized connection attempt


I successfully installed my freepbx and tried to make it as secure as possible, but I’m stuck with this one. I’ve enabled the security log and I have those lines popping up:

[2016-08-29 15:18:21] SECURITY[8536] res_security_log.c: SecurityEvent=“ChallengeSent”,EventTV=“2016-08-29T15:18:21.370+0200”,Severity=“Informational”,Service=“SIP”,EventVersion=“1”,AccountID=“sip:[email protected]”,SessionID=“0x7fd504abb798”,LocalAddress=“IPV4/UDP/my.ip.address/5060”,RemoteAddress=“IPV4/UDP/”,Challenge=“7c8fd67d”

My problem is that they are not followed by an event “SuccessfulAuth” nor “InvalidPassword” and I know it is not an authorized IP address. Do you have any idea what’s happening and how to prevent/correct it ? Because with this line alone I don’t think it’s relevant to make a fail2ban action.

Many thanks,