USER PROFILING BASED ON NETWORK APPLICATION TRAFFIC MONITORING
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There is increasing interest in identifying users and behaviour profiling from network traffic metadata for traffic engineering and security monitoring. However, user identification and behaviour profiling in real-time network management remains a challenge, as the activities and underlying interactions of network applications are constantly changing. User behaviour is also changing and adapting in parallel, due to changes in the online interaction environment. A major challenge is how to detect user activity among generic network traffic in terms of identifying the user and his/her changing behaviour over time. Another issue is that relying only on computer network information (Internet Protocol [IP] addresses) directly to identify individuals who generate such traffic is not reliable due to user mobility and IP mobility (resulting from the widespread use of the Dynamic Host Configuration Protocol [DHCP]) within a network. In this context, this project aims to identify and extract a set of features that may be adequate for use in identifying users based on their network application activity and timing resolution to describe user behaviour. The project also provides a procedure for traffic capturing and analysis to extract the required profiling parameters; the procedure includes capturing flow traffic and then performing statistical analysis to extract the required features. This will help network administrators and internet service providers to create user behaviour traffic profiles in order to make informed decisions about policing and traffic management and investigate various network security perspectives. The thesis explores the feasibility of user identification and behaviour profiling in order to be able to identify users independently of their IP address. In order to maintain privacy and overcome the issues associated with encryption (which exists on an increasing volume of network traffic), the proposed approach utilises data derived from generic flow network traffic (NetFlow information). A number of methods and techniques have been proposed in prior research for user identification and behaviour profiling from network traffic information, such as port-based monitoring and profiling, deep packet inspection (DPI) and statistical methods. However, the statistical methods proposed in this thesis are based on extracting relevant features from network traffic metadata, which are utilised by the research community to overcome the limitations that occur with port-based and DPI techniques. This research proposes a set of novel statistical timing features extracted by considering application-level flow sessions identified through Domain Name System (DNS) filtering criteria and timing resolution bins: one-hour time bins (0-23) and quarter- hour time bins (0-95). The novel time bin features are utilised to identify users by representing their 24-hour daily activities by analysing the application-level network traffic based on an automated technique. The raw network traffic is analysed based on the development of a features extraction process in terms of representing each user’s daily usage through a combination of timing features, including the flow session, timing and DNS filtering for the top 11 applications. In addition, media access control (MAC) and IP source mapping (in a truth table) is utilised to ensure that profiling is allocated to the correct host, even if the IP addresses change. The feature extraction process developed for this thesis focuses more on the user, rather than machine-to-machine traffic, and the research has sought to use this information to determine whether a behavioural profile could be developed to enable the identification of users. Network traffic was collected and processed using the aforementioned feature extraction process for 23 users for a period of 60 days (8 May-8 July 2018). The traffic was captured from the Centre for Cyber Security, Communications and Network Research (CSCAN) at the University of Plymouth. The results of identifying and profiling users from extracted timing features behaviour show that the system is capable of identifying users with an average true positive identification rate (TPIR) based on hourly time bin features for the whole population of ~86% and ~91% for individual users. Furthermore, the results show that the system has the ability to identify users based on quarter-hour time bin features, with an average TPIR of ~94% for the whole population and ~96% for the individual user.
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