Infa 620 Laboratory 2: Context And Purpose Of This Lab

Infa 620laboratory 2contextthe Purpose Of This Lab Is To Practice Exam

The purpose of this laboratory exercise is to analyze network traffic using Wireshark, a widely-used open-source packet analyzer, to identify and understand TCP handshake processes and recognize the characteristics of a SYN flood attack, which is a common Denial of Service (DoS) attack. This exercise emphasizes the importance of proficient packet analysis, domain knowledge, and the ability to interpret network traffic to diagnose potential security threats.

Participants will utilize pre-captured trace files (.cap files) representing normal TCP handshake communication and a simulated SYN attack. The primary tasks involve familiarization with Wireshark’s interface and features, analyzing the captured packets, and answering specific questions that deepen understanding of TCP/IP protocols and attack mechanisms.

Paper For Above instruction

Wireshark, as a tool, offers an in-depth look into network traffic by capturing and analyzing packets. The exercise begins with the stages of acquiring and opening the provided trace files: "tcpshake.cap" for a typical TCP handshake and "tcp-syn-attack.cap" for the SYN flood simulation. These files serve as the basis for comparative analysis. After opening the trace files, users should explore the interface, including the summary pane that lists packet details, the protocol tree with hierarchical protocol information, and the hex pane providing raw data representations.

Familiarity with Wireshark’s configuration options, such as disabling name resolution for clearer data, enhances the analysis process. When examining the "tcp-syn-attack.cap" file, users are prompted to answer ten detailed questions that test their understanding of TCP/IP protocol behavior during the attack scenario.

Firstly, determining if the communication is bidirectional involves analyzing the packet flow; normal TCP connections involve two-way exchanges, while SYN floods often exhibit unidirectional traffic. The absence or presence of ACKs helps identify whether the connection has been established. Since the SYN flood attack primarily involves SYN packets without completing the handshake, the presence or absence of ACKs is significant.

Secondly, examining the data portion length of each packet reveals that SYN packets typically carry no data, which aligns with TCP standards. The consistent zero value for sequence numbers and the changing port numbers in each packet are typical of attack traffic, where the attacker may use different source ports to evade detection.

The timing of packets, as viewed through the "Time" column and display format options, offers insight into the attack's intensity. Packets sent in rapid succession with minimal delay indicate malicious activity. By switching the time format to "Seconds since Previous Packet," users can measure how frequently packets are transmitted during the attack.

Protocol-specific details, such as the "Type" field within the protocol tree, help clarify whether the packet is a SYN, ACK, or other type of TCP segment. Inspection of TCP flags, especially in the transport layer, reveals which flags are active for each packet. Typically, SYN flags are set during an attack to initiate connection requests repeatedly without completing the handshake, thereby overwhelming the server resources.

Understanding how a SYN flood denies service involves recognizing that it exhausts the server’s connection handling capacity by flooding it with half-open connections (SYN packets without ACK responses), effectively making it unavailable to legitimate users. This is corroborated by the absence of subsequent ACKs and the predominance of SYN packets with minimal traffic following or preceding them.

This exercise demonstrates that recognizing such attacks requires a combination of sophisticated tools, detailed analysis, and domain knowledge. Proper interpretation of packet attributes, timing, flags, and flow direction enables security analysts to detect, understand, and mitigate DoS threats effectively.

References

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