Research On Secure Access Control Protocol In WLAN-based Mesh Networks

The emerging WMN (Wireless Mesh Networks) is a broadband access technology with the properties of multi-hop and self-organization. The WMN built on conventional IEEE 802.11 links is called a WLAN Mesh. WLAN Mesh inherits the desirable attributes such as low-cost and wide-deployment from WLAN, while acquired the advantages of mesh as vast coverage, scalability and robustness.However, it is still facing many challenges to put this promising technology into commercialized production. One of the major reasons is security consideration, especially the access control on the data link layer. The introduction of multi-hop and self-organization properties disables the adoption IEEE 802.11i security scheme, which is widely used in WLAN networks. To address this problem, the IEEE 802.11s task force proposed a new security framework called Mesh Security Association in the 802.11s draft, to secure link security of WLAN Mesh Networks. In this thesis, we discuss the secure access control of WLAN-based Mesh Networks. We first analyzed the motive, principle and defects of the proposed MSA mechanism. And based on that observation and study, we proposed a prototype providing MSA authentication support for off-the-shelf wireless devices and existing 802.11 network stack. Specifically, we implemented a PLM protocol exchange and designed an approach to incorporate it into the net80211 stack of Madwifi driver, and allow it to cooperate with 802.11i user-space clients, achieving user authentication of Mesh points and the cryptographic and key management functionality. Our preliminary evaluation result shows that, the PLM protocol implementation will make no significant effect on overall network performance in a single-hop, low retry-rate test case.