With the rapid growth of communication, applications in traffic sensor network such as the multimedia service Server Push, are indispensable to business advertising. The applications of server push, for example, the service Push Mail provided by ISP (Internet Service Provider), became much more hot and popular. This paper aims to design a mobile vehicular network to let the people who received the advertisement communicate with the providers of the service. Nevertheless, the handoff problem that arises when traveling brings down the quality of communication. Therefore, seamless handoff becomes a very important issue for us to research. This thesis uses the new SCTP (Stream Control Transmission Protocol) to solve the problem. SCTP not only keeps the advantages of TCP/IP but also provides new support. Allowing the user to own several IP addresses at the same time is one of its important characteristics, which allows you to switch to any other available IP immediately if the transmission is interruptted. With this characteristic, the user barely notices any interruption in the process of handoff. Finally, we propose a new design for SCTP to achieve a response time, and can be used in applications that require a fast response time.

<p>The objective with this thesis is to describe security mechanisms that are inte-grated or are proposed to be integrated with the Session Initiation Protocol (SIP). SIP is used for establishing, modifying, and terminating multimedia ses-sions over the IP network. This thesis is divided into two main parts, where the first part describes the implemented security mechanisms in SIP and the second part describes a number of proposed security mechanisms that may be implemented in SIP. At the end of the report there is a section that presents the scripts and results from different security tests that were performed on two implementations of SIP. Apart from describing different security mechanisms in the first part of this thesis, this section also contains an analysis on how possible security threats against SIP may be used to launch different attacks. The analysis also describes how these attacks may be prevented, if possible, by using the secu-rity mechanisms provided by SIP. The second part also contains an analysis section, which is focusing on finding the advantages and disadvantages of using a specific security mechanism compared to a similar security mechanism that is currently used or has been used in SIP. In the last section of this thesis I present my conclusions and a summary of the results.</p>

Då samordnad individuell plan infördes i lagstiftningen 1 januari 2010 var syftet att personer med behov av insatser från fler organisationer än en skulle erbjudas en samordnad individuell plan för att tydliggöra de olika organisationernas ansvar, och förbättra för den enskilde klienten. Syftet med vår studie var att undersöka hur samordnad individuell plan förändrat samverkan mellan kommun och landsting när det handlar om personer med dubbeldiagnos. Studien har bedrivits kvalitativt med en deduktiv strategi, där fyra yrkesverksamma inom en och samma stad har intervjuats. De teorier som användes var case managment samt systemteori. Våra slutsatser är att tillvägagångssättet bör förändras för att undvika extra arbete, det behövs ytterligare riktlinjer för hur samverkan skall bedrivas innan ett gott resultat av lagändringen kan ses, båda organisationerna lägger stor vikt vid klientens behov, klienten blir mer delaktig när SIP används samt att organisationerna behöver mer kunskap om varandras arbetsområden.

Ulm, Univ., Diplomarbeit, 2001.

The diploma thesis focuses on the VoIP technology optimization and performance management. The diploma thesis presents the theoretical basis of IP telephony and measurement of its quality. The thesis primarily deals with practical measurements of VoIP calls quality. Asterisk softswitch, various types of IP phones and simulated degradation of signal using Linux software router are used for measurements. Procedural diagram of VoIP technology real deployment is designed based on these measurements.

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-07-03T12:45:22Z No. of bitstreams: 1 arquivototal.pdf: 4171683 bytes, checksum: 4ac16c84db0389c70cded97b96f0569b (MD5) / Made available in DSpace on 2017-07-03T12:45:23Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4171683 bytes, checksum: 4ac16c84db0389c70cded97b96f0569b (MD5) Previous issue date: 2017-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Similar to others IP network based services, VoIP applications are quite vulnerable to dangerous distributed denial of service attacks (DDoS). Commonly, these attacks had been carried out by sending numerous requests to a SIP server (SIP flooding) in order to overload it. Although still harmful, such attacks can be easily identified by defenses that detect sudden changes in the network traffic volume. Most recent attacks, classified as Low-Rate, have bypassed such defense mechanisms attacking applications by generating traffic very similar to normal client traffic rendering such monitoring defenses ineffective. In a new form of DDoS attack called Telephony Denial of Service (TDoS), attacker has been using malicious calls to prevent legitimate clients to receive or to make calls. An example of a Low-Rate TDoS attack is the Coordinated Call Attack, where attackers simply make calls to each other to exhaust the target VoIP server’s resources. An efficient selective defense against Low-Rate attacks exploiting the HTTP protocol is the tool SeVen. This work demonstrates that selective strategies can also be successfully used to mitigate TDoS attacks, in particular, the Coordinated Call Attack. The contributions of this work are three-fold: (1) A selective strategy suitable for VoIP applications; (2) Formulating the defense in the Maude tool and conducting simulations using statistical model checker (PVeStA); (3) Experimental results show that without defense, less than 41% of users have access to the target VoIP service, whereas with the selective defense, availability is around 98%. / Assim como outros serviços baseados em redes IP, aplicações VoIP estão vulneráveis aos perigosos ataques distribuídos de negação de serviço (DDoS). Comumente, esses ataques eram efetuados enviando inúmeras requisições a um servidor SIP (SIP flooding), de modo a sobrecarregá-lo. Embora bastante prejudiciais, tais ataques podem ser facilmente identificados por defesas que detectam mudanças abruptas no volume de tráfego da rede. Ataques mais recentes, classificados como Low-Rate, conseguem sobrepujar essas defesas, atacando aplicações e gerando tráfego bastante similar ao de clientes normais, tornando tais defesas ineficazes. Em uma nova forma de DDoS denominada Negação de Serviço de Telefonia (TDoS - Telephony Denial of Service), atacantes vem fazendo uso de chamadas maliciosas para impedir que clientes legítimos consigam receber ou realizar chamadas. Um exemplo de TDoS Low-Rate é o Coordinated Call Attack, onde atacantes simplesmente realizam chamadas entre si para esgotar os recursos do servidor VoIP alvo. Uma defesa seletiva eficiente contra ataques Low Rate que exploram o protocolo HTTP é a ferramenta SeVen. O presente trabalho demonstra que estratégias seletivas também podem ser usadas com sucesso para mitigar ataques TDoS, em particular, o Coordinated Call Attack. As contribuições deste trabalho são de três tipos: (1) Uma defesa seletiva adequada para aplicações VoIP; (2) A Formalização da defesa na ferramenta Maude e condução de simulações usando um verificador estatístico de modelos (PVeStA); (3) Resultados experimentais mostram que sem defesa, menos de 41% dos usuários conseguem acessar o serviço VoIP alvo, enquanto que com a defesa seletiva, a disponibilidade fica em torno de 98%.

H.323 och Session Initiation Protocol är två olika protokoll som kan användas t ex för att koppla upp röstsamtal eller videosamtal via Internet. Det är ofta önskvärt i en uppkoppling mellan två personer att personerna kan autentisera sig för varandra. Denna autentisering är avsedd att garantera identiteten på deltagarna i kommunikationen. Den här undersökningen jämför protokollens struktur vid autentiseringen och visar skillnader i säkerhetssynpunkt. Autentisering finns i 3 skikt i de båda protokollen. I applikationsskiktet skiljer sig protokollen åt då SIP använder sig av lösenord för autentisering medan H.323 både kan använda lösenord och en PKI-baserad lösning med utbyte av nyckelcertifikat. I transportskiktet och nätverksskiktet kan båda protokollen använda TLS och IPSec för autentisering och därmed är det ingen större skillnad på protokollen i dessa skikt.

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 paper 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 Attack Detection and Prevention (DADP) scheme based on the usage of a non-blocking DNS cache. Based on various measurements conducted over the Internet we investigate the efficiency of the DADP scheme and compare its performance with different caching strategies applied. / nickchang918@hotmail.com

The objective with this thesis is to describe security mechanisms that are inte-grated or are proposed to be integrated with the Session Initiation Protocol (SIP). SIP is used for establishing, modifying, and terminating multimedia ses-sions over the IP network. This thesis is divided into two main parts, where the first part describes the implemented security mechanisms in SIP and the second part describes a number of proposed security mechanisms that may be implemented in SIP. At the end of the report there is a section that presents the scripts and results from different security tests that were performed on two implementations of SIP. Apart from describing different security mechanisms in the first part of this thesis, this section also contains an analysis on how possible security threats against SIP may be used to launch different attacks. The analysis also describes how these attacks may be prevented, if possible, by using the secu-rity mechanisms provided by SIP. The second part also contains an analysis section, which is focusing on finding the advantages and disadvantages of using a specific security mechanism compared to a similar security mechanism that is currently used or has been used in SIP. In the last section of this thesis I present my conclusions and a summary of the results.

Gateways handle many functions in todays telecommunication networks and as the move towards IP-based telecommunication networks continue, their importance is growing. Many vendors offer a tiered architecture where logic is separated from the gateways for easy extensibility. Currently gateway control and gateway communication is handled using the H.248 protocol. As more and more equipment starts moving over to SIP based communication there has been a degree of interest in homogenizing the system and possibly replacing the H.248 protocol with a SIP based protocol. In this paper we examine how the communication between a gateway controller and gateway may look if implemented in SIP. We also examine the performance characteristics of the proposed protocol from both an execution time, communication size and memory consumption perspective. Implementation and tests will be performed using a language, developed by Ericsson specifically for the telecommunication sector, called Erlang. The protocol designed herein is not intended for production use and is only examined for viability. It is NOT the official stance of Ericsson that H.248 will be replaced with the protocol or any like it.