lwIP is a compact TCP/IP protocol suite designed to minimize RAM usage while offering full TCP functionality, ideal for embedded systems with limited memory. Developed by Adam Dunkels at SICS, lwIP now benefits from a global network of developers. Notable features include support for IPv4/IPv6, ICMP, IGMP, MLD, ND, DHCP, UDP, TCP, PPPoS, DNS, and more. The stack is available under a BSD license, with ongoing contributions and improvements via Git and Savannah. Development information, documentation, and resources can be found on the project page. Additionally, Dunkels’ papers and source code documentation provide insights into lwIP’s design.
https://www.nongnu.org/lwip/2_1_x/index.html