Personal firewall in mobile phone

Abstract

The assignment described in this master thesis is given by Ericsson AS and gives an evaluation of a need for a personal firewall in mobile phone. In today’s commercial products personal firewall in mobile phone does not exist. This master thesis analyzes the role of personal firewall in different scenarios. At the beginning of the master thesis functions that already exist in personal firewall for PC were discussed in the sense of which could be useful in personal firewall for mobile phone. This master thesis also covers description of connection between personal firewall and virus in addition to what personal firewall can do to prevent virus and other malicious software. Different types of attacks (Denial of Service, Port Scanning, IP spoofing, etc.) and what personal firewall can do to prevent such attacks were evaluated. Mobile phone’s specific functions (Billing & Charging), mobile phone standard functions (WAP/WWW) and P2P services over IP (Push-To-Talk, Buddy list and Wireless Village) need support from a personal firewall so that users feel more secure using them. Furthermore, personal firewall protection is essential regarding downloadable applications from the Internet. Connection types: GPRS/UMTS, WLAN and Bluetooth are discussed to be vulnerable to different types of attacks. Functions in personal firewall that could prevent these attacks were outlined. Possible ways to implement personal firewall for various connection types were also suggested. One possible way to implement personal firewall could be as software in mobile phone for all connection types. It is also possible to implement it in the GGSN and in mobile phone for GPRS and UMTS. Operators offer services in GGSN’s personal firewall while user can add several rules. This implementation is best suitable for GPRS and UMTS. Personal firewall as software implemented in the mobile phone is configured by a user and suitable for all connection types. An analysis of personal firewall implementations with their advantages and disadvantages are proposed in this master thesis. Discussion on different layers in mobile phone and what underlying functionality mobile phone must provide to get a working personal firewall was also covered. Aspect of packets filtering has also been evaluated: network filtering, filtering in personal firewall and application level filtering. If filtering is done in IP layer, it is fast and less secure comparing to application level filtering. IP filtering is based on the header information, while application level filtering is based on content of the whole packet. Filtering in personal firewall includes a part of IP stack responsible for filtering. I have found that the need for personal firewall in mobile phone with proposed useful functions is essential. Even though implementation of personal firewall could be difficult, it is better then no protection at all.