Because Linux is a UNIX system, its primary network protocol is TCP/IP. Other protocols can be used with Linux, but TCP/IP is the most widely used because it is included with each Linux software package and is the default network protocol. TCP/IP’s role as the protocol of the Internet also makes it popular.

TCP/IP is usually used over Ethernet networks, so most of Linux’s networking systems are designed around Ethernet. Many Ethernet network interface cards (NICs, also called network adapters) are available. The most popular Ethernet cards from 3Com, Novell, Western Digital, Hewlett Packard, and Intel all work cleanly with Linux. Many compatible Ethernet NICs from other vendors also function properly.