BSD对UNIX最重要的贡献之一是TCP/IP。BSD 有8个主要的发行版中包含了TCP/IP：4.1c、4.2、4.3、4.3-Tahoe、4.3-Reno、Net2、4.4以及 4.4-lite。这些发布版中的TCP/IP代码几乎是现在所有系统中TCP/IP实现的前辈，包括AT&T System V UNIX 和Microsoft Windows中的TCP/IP都参照了BSD的源码。-BSD of UNIX is one of the most important contributions TCP/IP. There are 8 major BSD releases included in TCP/IP: 4.1c ,4.2,4.3,4.3-Tahoe ,4.3-Reno, Net2, 4.4, and 4.4-lite. The release of the TCP/IP code in almost all systems now TCP/IP implementation of the predecessors, including AT &　T System V UNIX and Microsoft Windows in the TCP/IP are the light of the BSD source code.