Improvised Nymble Model for Blocking Misbehaving Clients in Anonymizing Networks Rutuja Shah Varsha Anandani Prof.S.S.Manivannan M.Tech-I.T (Networking) M.Tech-I.T. (Networking) SITE VIT Vellore VIT Vellore VIT Vellore shah.rutuja.89@gmail.com varshu.anandani@gmail.com manivannan.ss@vit.ac.in Abstract: In anonymous networks clients are allowed to access internet without compromising their privacy. Anonymizing networks provides this private sharing by using a series of routers that implements onion routing wherein the IP Address of client is hidden. Generally the websites require IP Address to uniquely identify the client and if any client tries to access the website without any valid IP Address then website administration blocks that client. Blocking IP Address is not feasible as IP Addresses are limited. Blocking an unauthorized client is needed for security but if the client is anonymous then this solution fails here. This will treat behaving and misbehaving clients alike. The aim of Misbehaving clients is to make the servers down or deface it. In existing extended Nymble system, the Nymble Manager blocks misbehaving clients temporarily for a default period of time, to avoid this there is a pseudotracker to track client’s rating. In our Enhanced Nymble system the right of blocking misbehaving clients is solely given to the server and the need of a different pseudotracker and communication between PM and NM through pseudotracker is eliminated thus making the Nymble system more efficient maintaining the confidentiality of the client at the same time. Keywords: Anonymous Tracking, Anonymous blacklisting, Enhanced Nymble Manager, Rating, Privacy I. INTRODUCTION In Anonymizing networks clients are not bounded to share their IP Address to ensure their privacy but some miscellaneous clients misuse this capability of networking-under this anonymous cover by impairing well known websites such as Amazon. In order to overcome this issue website administrators generally prefer blocking all the clients in the entire network at the cost of denial of access of internet for anonymous honest clients. Anonymizing networks works upon onion routing. But, blocking each of such IP addresses is cumbersome and at the same time, blocking of IP-address is not a feasible idea due to limited availability of IP addresses. Since if a IP address is blocked permanently it will be as a waste of one IP address which could have been assigned to a honest client. So a new technology for anonymizing networks was introduced in order to address this problem, wherein the clients’ confidentiality is maintained by not revealing its IP address and at the same time getting access rights for a particular server. In case of misbehavior, the Nymble Manager(NM) was given the right to blacklist the client access. A Pseudotracker(PT) was maintained to keep the track of client’s rating anonymously by maintaining the client’s login details(resources) and the respective rating. If a client misbehaves /impairs a server, server would complain it to NM using the Access Ticket and NM would in turn request the Pseudonym Manager(PM) to find out the client’s rating depending on its pseudonym.PM would ask Pseudotracker to check the client’s rating and return it to PM.PM will give the rating value from PT to NM. In the end, NM would blacklist/forgive the client depending on its criticality. For a newly misbehaved client, rating will be higher say 3.As and when the client will misbehave with different servers the rating will get deteriorated consequently. The right to forgive/blacklist client is given to NM. However, there are few notable loopholes in this earlier nymble systems. Those will be explained in the later part of our paper.