Mobile WLAN access point for the ETH shuttle bus

Abstract

The goal of this semester thesis and the ensuing project was to develop a mobile Access Point for Wireless LAN (IEEE 802.11b), applicable in the shuttle bus that connects the two campi ETH Zentrum and ETH Hönggerberg. A proper Wide Area Wireless Technology was evaluated and an according interface was set up.This interface and a software-based Access Point were implemented on an embedded device (Set Top Box), operated by an embedded Linux (LEAF) which routes the traffic between the two interfaces. The system characteristics were tested and evaluated. The access to the WLAN must be granted for users with a n.ethz account and should be transparent, i.e. authentication and access procedure are the same as on the fixed Access Points in the ETH WLAN. There are two authentication concepts: • Old Access Concept: The user authenticates via SSH connection on a validation server. The validation server unlocks the user’s IP address on the gateway firewall to the ETH LAN. • New Access Concept: The user authenticates on a VPN-server and establishes a VPN-tunnel to the latter by using a dedicated VPN-software, whence he can access the ETH LAN and thence the Internet. To realize the Access Point, two different system concepts were imple mented and evaluated: • System Concept I was implemented as a first prototype. It supports the New Access Concept only. • System Concept II supports the Old Access Concept as well, yet was more sophisticated and therefore more difficult to realize. Its implementation was the main motivation for the ensuing project. The labour and the investigations within the scope of this project realized a mobile Access Point that supports both of the above mentioned access concepts, but also revealed difficulties and limitations. The Wide Area Wireless Technology (GPRS) that connects the bus to the ETH WLAN, forms a bottleneck concerning data rate and delay.