Detecting intruders attempting to gain access to the system or who are intentionally creating a denial-of-service or similar type of disturbance can be a challenge. While it may seem obvious what type of traffic would be considered unusual, there are edge cases that must be considered when setting up rules for automatic detection and blocking of hacking attempts.
Some tools overwhelm VoIP systems by sending fake authorization attempts to them without ever responding to the challenge request that is used in SIP. One popular tool is often referred to as friendly scanner or SIPvicious. These types of tools keep a system busy handling bogus requests, overloading the system, making it difficult to handle real requests, and so on. Another suspicious behavior can be detected from someone trying to make long distance or international calls repeatedly within a short time period.
FreeSWITCH provides the ability to log a warning when an attempt...