A method for estimation of performance characteristics for transport control protocol includes sparsely sampling, at a middlebox, a plurality of packets from a transport control protocol (TCP) connection between a source endpoint and a destination endpoint through the middlebox. For each packet of the sampled plurality of packets, the method includes generating a time stamp when the packet is sampled and recording a sequence number and an acknowledgement number for the respective packet. The acknowledgement number is recorded when the acknowledgement number exists for the respective packet. The method also includes generating an estimated performance characteristic for the TCP connection between the source endpoint and the destination endpoint through the middlebox over the period of time based on at least two of a respective time stamp, a respective sequence number, or a respective acknowledgement number from one or more of the sampled plurality of packets.