ppp0

ppp0 is the first Point-to-Point Protocol (PPP) network interface on many Unix-like operating systems. It is created when a PPP session is established, such as with traditional dial-up connections, PPP over Ethernet (PPPoE), or other PPP-based links. The interface is named in a sequence (ppp0, ppp1, etc.) as additional sessions are opened.

PPP is a data link layer protocol that encapsulates network-layer traffic over serial or point-to-point links. It supports multiple network layer protocols through Network Control Protocols, most commonly IPCP for IPv4 and IPv6CP for IPv6. PPP provides options for authentication (e.g., PAP, CHAP), compression, and link negotiation. In practice, a PPP session negotiates IP addresses and other parameters, and once established, traffic is routed over the ppp0 interface as if it were a local network interface.

Creation and management of ppp0 typically involve the PPP daemon (pppd) or a PPPoE plugin. Configuration can be performed via system files such as /etc/ppp/options and per-connection scripts, or through network management tools like NetworkManager. The interface’s lifecycle includes up and down events triggered by connection establishment and termination, with associated user-space scripts running at connect/disconnect time.

Usage considerations include that ppp0 represents the active PPP session and will receive a local and remote IP address assigned during IPCP/IPv6CP negotiation. Firewall rules, routing, and DNS configuration are often adjusted to accommodate the PPP connection. While ppp0 is the conventional name, some environments may suffix or rename interfaces differently depending on the platform and management framework.