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TCP sequence numbers and receive windows behave very much like a clock. The receive window shifts each time the receiver receives and acknowledges a new segment of data. Once it runs out of sequence numbers, the sequence number loops back to 0. When a receiver advertises a window size of 0, the sender stops sending data and starts its persist ...
If this sequence number is acknowledged, TCP returns to the congestion avoidance state. A problem occurs with New Reno when there are no packet losses but instead, packets are reordered by more than 3 packet sequence numbers. In this case, New Reno mistakenly enters fast recovery.
A TCP sequence prediction attack is an attempt to predict the sequence number used to identify the packets in a TCP connection, which can be used to counterfeit packets. [1] The attacker hopes to correctly guess the sequence number to be used by the sending host. If they can do this, they will be able to send counterfeit packets to the ...
SYN cookie is a technique used to resist SYN flood attacks. The technique's primary inventor Daniel J. Bernstein defines SYN cookies as "particular choices of initial TCP sequence numbers by TCP servers." In particular, the use of SYN cookies allows a server to avoid dropping connections when the SYN queue fills up.
Checksum and sequence number calculations - again a burden on a general purpose CPU to perform. Sliding window calculations for packet acknowledgement and congestion control. Connection termination. Moving some or all of these functions to dedicated hardware, a TCP offload engine, frees the system's main CPU for other tasks.
A number of extensions have been made to TCP over the years to increase its performance over fast high-RTT links ("long fat networks" or LFNs). TCP timestamps (RFC 1323) play a double role: they avoid ambiguities due to the 32-bit sequence number field wrapping around, and they allow more precise RTT estimation in the presence of multiple ...
Sequence numbers modulo 4, with w r =1. Initially, n t =n r =0. So far, the protocol has been described as if sequence numbers are of unlimited size, ever-increasing. However, rather than transmitting the full sequence number x in messages, it is possible to transmit only x mod N, for some finite N. (N is usually a power of 2.)
For instance, a case where sequence number field of TCP header is manipulated, the encoding scheme is adopted such that every time the same alphabet is covertly communicated, it is encoded with the same sequence number. Moreover, the usages of sequence number field as well as the acknowledgment field cannot be made specific to the ASCII coding ...