er may be requesting to access a web browser, application, e-mail, voicemail, network etc. This is achieved by the attacker by creating a horde of network traffic in the target machine by the control of more than one remotely-controlled computer. When the target machine will flood with attacker's requests, it will lose time to send response to user's request. DDoS attacks can be categorized into two groups: Semantic attacks Brute-force (flood) attacks. Semantic attack works by taking advantage of a bug or glitch in the applications or protocols installed in the user's machine. It avails that ingredient of the application and consumes its resources in an inordinate amount. For instance, the attacker can deliver a series of packets across the server in order to inaugurate CPU time consuming operations. With large number of such requests, the target machine will be impotent to handle requests from authorized users. This attack can be abridged by regular updates of software and protocols in addition with implementation of exclusive filter mechanisms. Downloaded: 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Analysis of Issues in SDN Security and Solutions ATTACK TECHNIQUES Network Based Attacks TCP SYN Flooding DoS attacks are usually intended to employ stateful network protocols as they drain resources to maintain states. One such attack is TCP SYN flooding. It has an ample repercussion on many systems. On ensconcing a TCP connection to a server, a SYN message is send by the client to the server which acknowledges the message and sends a SYN-ACK message to the client. The connection is established when the user reciprocate with an ACK message. After successful connection establishment, client and server can exchange service-specific data. The debasement between client and server arises at half-open state when after sending the SYN-ACK message to the client, it does not receive the client's ACK message for a long duration. This information of the half-open connection needs to be stored by