TCP Maximum Segment Size
TCP/IP Stack always inserts Maximum Segment Size (MSS) field in the header. This causes difference in MSS insertion behavior with and without TCP Proxy.
Using tcp mss configurations, TCP MSS can be limited if already present in the TCP SYN packets. If there are no errors detected in IP header or TCP mandatory header, and there are no memory allocation failures, TCP optional header is parsed. If TCP MSS is present in the optional header and its value is greater than the configured MSS value, the value present in the TCP packet is replaced with the one that is configured.
If the TCP optional header is not present in the SYN packet and there are no errors in already-present TCP header, the configured TCP MSS value is inserted while sending out the current packet.