veth0

veth0 is the first end of a virtual Ethernet pair in the Linux kernel. A veth pair consists of two interconnected virtual interfaces, typically named veth0 and veth1. Data sent to one end appears on the other, effectively creating a point-to-point link that exists entirely in software.

Veth pairs are commonly used to connect network namespaces and containers to the host network or to a bridge. They are created as paired devices, then one end is placed in the target namespace or attached to a bridge, while the other end remains in the host namespace. Typical workflow includes creating the pair, bringing both ends up, moving one end into a container or namespace, and configuring IP addresses in each environment. A bridge such as br0 can be used to provide external connectivity by attaching one end of the pair to the bridge.

A veth device functions like a regular Ethernet interface but has no hardware backing. It supports MAC addresses, MTU settings, and VLANs, but it does not rely on a physical NIC and has no hardware offload. Veth pairs are ephemeral and managed by user-space tools; they can be recreated on reboot or by container runtimes and network managers.

Naming conventions are conventional rather than mandatory. veth0 is a common host-end name, with the peer often named veth1, though names are arbitrary and may be renamed or remapped when entering a container or namespace.

See also: Linux network namespaces, veth pairs, bridges, container networking (CNI).