Clever, yes. But this will break in presence of middle-boxen that rewrite IP-ID [1] and/or TCP-SEQ/ACK [2] numbers (SSL inspection firewalls, WAN optimizers, ol

Clever, yes. But this will break in presence of middle-boxen that rewrite IP-ID [1] and/or TCP-SEQ/ACK [2] numbers (SSL inspection firewalls, WAN optimizers, older satellite modems, even some particularly bad carrier-grade NAT devices). [1] https://en.wikipedia.org/wiki/IPv4#Identification https://en.wikipedia.org/wiki/IPv4#Identification [2] https://en.wikipedia.org/wiki/Transmission_Control_Protocol#TCP_segment_structure https://en.wikipedia.org/wiki/Transmission_Control_Protocol#...