Detecting change in a transport protocol window size without data transmission

A method, comprising the computer-implemented steps of:

• receiving, from a TCP application, a first data segment that comprises a first receive window size of zero;
• determining whether data needs to be sent to the TCP application;
• in response to the receiving and determining, creating and sending a second segment that contains a first sequence number value equal to a second sequence number of sent but unacknowledged data minus one, and a segment length value of zero;
• receiving a third segment that comprises a second receive window size;
• determining whether the second receive window size is greater than a first value that is greater than or equal to one;
• wherein the first value is based at least in part on a size that prevents data fragmentation;
• sending data only when the second receive window size is greater than the first value.

A volatile or non-volatile computer-readable medium carrying one or more sequences of instructions for detecting a change in a data transmission window size, which instructions, when executed by one or more processors that host a transmission control protocol (TCP) process in a network element, cause the one or more processors to perform the steps of:

• receiving, from a TCP application, a first data segment that comprises a first receive window size of zero;
• determining whether data needs to be sent to the TCP application;
• in response to the receiving and determining, creating and sending a second segment that contains a first sequence number value equal to a second sequence number of sent but unacknowledged data minus one, and a segment length value of zero;
• receiving a third segment that comprises a second receive window size;
• determining whether the second receive window size is greater than a first value that is greater than or equal to one;
• wherein the first value is based at least in part on a size that prevents data fragmentation;
• sending data only when the second receive window size is greater than the first value.

A network element, comprising:

• one or more processors;
• means for receiving, from a TCP application, a first data segment that comprises a first receive window size of zero;
• means for determining whether data needs to be sent to the TCP application;
• means for creating and sending, in response to the receiving and determining, a second segment that contains a first sequence number value equal to a second sequence number of sent but unacknowledged data minus one, and a segment length value of zero;
• means for receiving a third segment that comprises a second receive window size;
• means for determining whether the second receive window size is greater than a first value that is greater than or equal to one;
• wherein the first value is based at least in part on a size that prevents data fragmentation;
• means for sending data only when the second receive window size is greater than the first value.

An apparatus, comprising:

• one or more processors;
• a network interface coupled to a network for communicating one or more packet flows to the network;
• a volatile or non-volatile computer-readable medium accessible to the one or more processors and carrying one or more sequences of instructions for preventing network reset attacks, which instructions, when executed by one or more processors that host a transmission control protocol (TCP) process in a network element, cause the one or more processors to perform the steps of:
• receiving, from a TCP application, a first data segment that comprises a first receive window size of zero;
• determining whether data needs to be sent to the TCP application:
• in response to the receiving and determining, creating and sending a second segment that contains a first sequence number value equal to a second sequence number of sent but unacknowledged data minus one, and a segment length value of zero;
• receiving a third segment that comprises a second receive window size;
• determining whether the second receive window size is greater than a first value that is greater than or equal to one;
• wherein the first value is based at least in part on a size that prevents data fragmentation;
• sending data only when the second receive window size is greater than the first value.