lwIP + A Lightweight TCP-IP stack - lwIP is a lightweight implementation of the TCP-IP protocol stack. The focus of the lwIP TCP-IP implementation is to reduce RAM usage.
Miniweb - Tiny proof+of+concept combined implementations of TCP and HTTP.
SCPS+TP - A suite of protocols aimed at space users. Includes an implementation of a protocol extending TCP.
sevenstax - Commercial TCP-IP implementation for embedded processors.
TCP Implementation WG Mail Archive - The IETF tcpimpl working group was shut down in Sep 2000, but the mailing list still exists. Historic archive may also be of interest.
TCP+BFA - Implementation from Stanford; TCP Buffer Fill Avoidance. [PDF]
TinyTCP-TinyFTP - A simple implementation of TCP and FTP, suitable for burning into ROM. It is, in effect, a hack put together in two or three days written in C++in 1986.
The uIP TCP-IP Stack for Embedded Microcontrollers - An implementation of the TCP-IP protocol stack that uses very little resources. Code size is on the order of a few kilobytes and memory usage is on the order of a few hundreds of bytes.
Xinu TCP implementation - The implementation of TCP used in Comer's Xinu Unix+like operating system.
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