Efficient Detection of VoIP Calls Hidden in Web Traffic
Network managers face nowadays a challenging problem to detect traffic from Skype. Skype can operate behind many firewalls and network proxies without user configuration. Behind restrictive firewalls, Skype uses Web TCP ports (80 or 443) as a fallback mechanism to delude firewalls and other network elements. The authors propose the adoption of non-extensive entropy to detect anomalies in network traffic within an Autonomous System (AS). They show that their approach based on chi-square test outperforms previous ones based on non-extensive entropy while providing enhanced flexibility, which is enabled by the possibility of the detection mechanism.