Effects Dns Flooding On Sip Voip Infrastructures Essay

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Effects DNS Flooding on SIP VoIP Infrastructures This assignment is presented as part of PG Diploma in IT (CODE-PGDIT-04) Cambridge college of learning June 2008 By Hidayatllah Dalpa Abstract A simple yet effective Denial of Service (DoS) attack on SIP servers is to flood the server with requests addressed at irresolvable domain names. In this thesis we evaluate different possibilities to mitigate these effects and show that over-provisioning is not sufficient to handle such attacks. As a more effective approach we present a solution called the DNS cache solution based on the usage of a non-blocking DNS cache. Based on various measurements conducted over the Internet we investigate the efficiency of the cache solution and compare its performance with different caching replacement policies applied. Introduction As opposed to PSTN (Public Service Telephone Network), VoIP (Voice over Internet protocol) providers such as skype are more and more welcomed with taking advantage of its low cost. However, the new network problems, like packet loss and Quality of Services (QoS) are emerging to the VoIP users. In the past, Security threats are considered minimal in current circuit switched networks. This is achieved by using a closed networking environment dedicated to a single application. However, for the VoIP services, which are based on an open environment such as internet, the systems are totally exposed to the attackers. In order to afford a broad service, the VoIP proxies can be accessed with a flat Internet access rate by anybody. Therefore, it is possible for an attacker to launch a DoS (Denial of Service) attack to VoIP proxies with a low cost. SIP (Session Initial Protocol) is a protocol proposed standard for initiating, modifying and terminating an interactive user session that involves multimedia elements

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