Tcp transport layer Er. Vikram Dhiman lpu discussion from last topic

Types of Attacks

• Syn flooding attack
• Simultaneous open

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SYN Flooding Attack The connection establishment procedure in TCP is susceptible

• SYN Flooding Attack The connection establishment procedure in TCP is susceptible
• to a serious security problem called the SYN flooding attack. This happens when a malicious
• attacker sends a large number of SYN segments to a server, pretending that each
• of them is corning from a different client by faking the source IP addresses in the datagrams.

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• The server, assuming that the clients are issuing an active open, allocates the
• necessary resources, such as creating communication tables and setting timers. The
• TCP server then sends the SYN +ACK segments to the fake clients, which are lost.

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• During this time, however, a lot of resources are occupied without being used. If, during this
• short time, the number of SYN segments is large, the server eventually runs out of
• resources and may crash. This SYN flooding attack belongs to a type of security attack known as a denial-of-service attack,

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• A SYN segment cannot carry data, but it consumes one sequence number.

• Note

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• A SYN + ACK segment cannot carry data, but does consume one sequence number.

• Note

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• An ACK segment, if carrying no data, consumes no sequence number.

• Note

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• Figure 23.19 Data transfer

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• Figure 23.20 Connection termination using three-way handshaking

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• The FIN segment consumes one sequence number if it does not carry data.

• Note

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• The FIN + ACK segment consumes one sequence number if it does not carry data.

• Note

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• Figure 23.21 Half-close