LPIC-1 Exam 102: Networking Fundamentals

Persistent Network Configuration

• In a TCP/IP network, each node must configure its network adapter to match the network requirements to enable communication.
• The system administrator must provide the basic configuration so the operating system can set up the appropriate network interface and identify itself and the network features at boot time.

NetworkManager

• Most Linux distributions use NetworkManager as a service daemon to configure and control the system's network connections.
• NetworkManager's purpose is to make network configuration simple and automatic.
• It arranges route changes, IP address fetching, and updates to the local list of DNS servers when using DHCP.
• It prioritizes wired connections over wireless connections by default.
• It tries to keep at least one connection active at all times, whenever possible.

Network Configuration Files

• /etc/hostname and /etc/hosts are used for basic TCP/IP host configuration.
• /etc/nsswitch.conf and /etc/resolv.conf are also used for network configuration.
• /etc/systemd/network files are used to override network settings.
• Files ending in .netdev are used by systemd-networkd to create virtual network devices.
• Files ending in .link set low-level configurations for network interfaces.
• Files ending in .network set up network addresses and routes.

systemd-networkd

• systemd-networkd detects and configures network devices automatically as they appear.
• It ignores devices already configured by other means.
• There is little need to add configuration files in most situations.
• Configuration files can be used to select specific network interfaces using the [Match] section.
• Matching rules can be based on network interface names, MAC addresses, or shell-style globs.