A network interface is an interface that enables a computer or a network component to access a computer network. Colloquially it is also called port or network connection . Today they are often integrated on the motherboard of PCs .
A typical network interface for PCs is one of the variants of the Ethernet standard. It offers a network connection, usually in the form of an RJ-45 socket, to which a twisted pair cable is connected. Older network cards also have a BNC connection. A connection for fiber optic cables is also possible. The network connection of a modem or an ISDN card is also a network interface.
In addition to physical network interfaces, logical network interfaces can also be configured on network components or end devices. These are required, for example, when the device is a participant in several logical networks ( VLANs ) that are brought in via a single physical network interface.
A wireless network interface (also called radio interface or incorrectly called air interface ) enables connection to a WLAN or cellular network .
A single network interface is usually sufficient for an end device to gain access to a network. Other components in a network, on the other hand, require multiple network interfaces. A bridge has at least two network interfaces, as several network segments are connected with one another. Also have hubs and switches multiple network interfaces. Also routers have usually more than one interface; If the router, on the other hand, transmits data exclusively between virtual networks, this can be done via a single interface ("router-on-a-stick").
A network interface can also be software that enables the computer to access a computer network, for example a device driver .