# Studying the Impact of Different TCP DoS Attacks on the Parameters of VoIP Streams
## 2 Related Work
In [39], the authors extensively review various technologies and methods for early warning of a DoS attack on a VoIP network intended to protect the users/administators of the attacked VoIP network from a DoS attack. Additionally, the authors discuss various vulnerabilities in VoIP networks and tests to detect those vulnerabilities. In [40], the authors consider caller-ID (caller-identification) spoofing attacks because through these attacks, an attacker can very easily access important information transmitted over SIP. Due to the fact that these attacks can take place only in a closed system (VoIP network only), they are not a subject of research and therefore, solutions to deal with these attacks are few. Therefore, the authors propose Blockchain-Based Caller-ID Authentication (BBCA), their blockchain-based defense mechanism, to prevent these attacks. In [41], the authors propose the use of machine learning as a replacement for rule-based systems to detect DoS attacks. For the purpose of the study, the authors created an experimental setup in which both useful traffic and traffic caused by a DoS attack was exchanged. Through this setup, the authors investigated the effectiveness of certain machine-learning methods for classifying traffic (useful or dangerous traffic) based on the extracted information. In [42], the authors propose a new type of SIP-based attack--Distributed Reflection Denial-of-Service (DRDoS). The purpose of this new attack was to expose the little-known capabilities of the SIP protocol. Additionally, the authors developed a simulator for these attacks, called Mr. SIP, which was used to generate the attack. The attack developed by the authors increased the CPU load of the attacked VoIP server dramatically, by up to 100%. Furthermore, due to the structure of the newly created attack, it could not be recognized as an attack, so it could not be filtered by firewalls, IDS/IPS systems, traffic-anomaly-detection systems, etc. The authors propose a defense mechanism for their attack that reduced the increase in CPU load during the attack from up to 100% without the protection mechanism to up to 18%. In [43], the authors consider Distributed Denial of Service (DDoS) threats, specifically INVITE flooding attacks. To detect these attacks in time, the authors propose the use of a GRU-based Intrusion-Detection System (IDS). This GRU-based Intrusion-Detection System (IDS) was based on recurring neural networks, which process the SIP traffic in real time and efficiently identify attack patterns in the traffic. The ability of the developed IDS to capture temporary dependencies increased the accuracy with which it classified and detected attack behaviors. In [44], the authors provide a thorough review of methods to secure VoIP platforms. The result of their study was that the existing ways to secure such systems are mainly focused on securing the network layer, while there are not enough measures aimed at securing SIP-based real-time VoIP communication at the application level. The goal set by the authors was to improve the security of the communication in VoIP systems by studying key technologies for detecting network attacks targeting SIP-based calls. In [45], the authors propose the use of an IDS system they developed that verifies the content of the SIP messages in the processed traffic. The rule definition was applied to intrusion detection, sending fake SIP denial-of-service messages, and flooding with incorrect packets. The data collection to verify the developed IDS system was carried out in two stages; in the first stage, the VoIP system was not attacked, and in the second stage, it was attacked. The tests showed that, when using the k-nearest neighbors, the developed IDS system had the highest detection accuracy, at 99.8%. In [46], the authors propose the use of a novel framework called \"Call Me Maybe\", which uses a combination of delay measurement and dynamic protocol switching to prevent DoS attacks in a VoIP system.