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Authentication, authorization, and accounting services provide the framework on top of which a reliable, secure, and robust accounting system can be built. In a previous work of ours, we have presented a flexible and, most importantly, generic accounting scheme for next generation networks. In this paper, we substantially improve our previous work by providing the required Diameter application namely SIP-Accounting (SIPA) that enables the use of our accounting scheme for Session Initiation Protocol (SIP) services. Additionally, in an effort to protect the service providers and the end users against accounting frauds, we implement an add-on mechanism referred to as SIPA+ to combat attacks targeting the core accounting functions and the integrity of the respective accounting messages. Using the implemented SIPA and SIPA+ prototypes, we conducted a complete set of experiments testing several configurations and two distinct scenarios. The results reveal that the proposed accounting system and its security add-on are fully operable in SIP environments without incurring much cost in terms of performance and overhead.

Accounting along with Authentication and Authorization comprise the concept of AAA provided by IETF (Internet Engineering Task Force). In heterogeneous environments, where different administrative domains and different wired and wireless technologies are utilized, those principles are often hard and complex to correctly implement and evaluate. Specifically, accounting which is our topic of interest, is in many cases a complicated procedure since many aspects need to be taken into consideration. In this respect, a distributed, flexible, robust, secure and generic accounting system needs to be implemented in order to provide the ability to determine which user has acquired which services and for how long at each operator domain. This work examines different scenarios applicable to such 3G/4G hybrid mobile environments and suggests a novel, generic mechanism to support accounting.

Robust Security Network (RSN) epitomised by IEEE 802.11i substandard is promising what it stands for; robust and effective protection for mission critical Wireless Local Area Networks (WLAN). However, despite the fact that 802.11i overhauls the IEEE's 802.11 security standard several weaknesses still remain. In this context, the complementary assistance of Wireless Intrusion Detection Systems (WIDS) to deal with existing and new threats is greatly appreciated. In this paper we focus on 802.11i intrusion detection, discuss what is missing, what the possibilities are, and experimentally explore ways to make them intertwine and co-work. Our experiments employing well known open source attack tools and custom made software reveal that most 802.11i specific attacks can be effectively recognised, either directly or indirectly. We also consider and discuss Distributed Wireless Intrusion Detection (DIDS), which seems to fit best in RSN networks.