NetworkManager

NetworkManager is a daemon that sits on top of libudev and other Linux kernel interfaces (and a couple of other daemons) and provides a high-level interface for the configuration of the network interfaces. NetworkManager is a software utility that aims to simplify the use of computer networks. NetworkManager is available for Linux kernel-based and other Unix-like operating systems. To connect computers with each other, various communications protocols have been developed, e.g. IEEE 802.3 (Ethernet), IEEE 802.11 ("wireless"), IEEE 802.15.1 (Bluetooth), PPPoE, PPPoA, and many many more. Each participating computer must have the suitable hardware, e.g. network card or wireless network card and this hardware must be configured accordingly to be able to establish a connection. In case of a monolithic kernel all the device drivers are part of it. The hardware is accessed (and also configured) through its device driver. In case of Linux, the kernel presents for each device driver a representation in form of a . All device files are found in the /dev directory, and traditionally the device files for Ethernet hardware have been named eth0, eth1, etc. Since systemd, they are named differently: enp4s0, etc. (This abstraction is called the concept.) Anything in user-space accesses the hardware through its device file. The configuration utility to configure the hardware, and programs like the web browser/SSH/NTP-client/etc. to send and receive network packets. On Linux and all Unix-like operating systems, the utilities ifconfig and the newer ip (from the iproute2-bundle) are used to configure IEEE 802.3 and IEEE 802.11 hardware. These utilities configure the kernel directly and the configuration is applied immediately. After boot-up, the user is required to configure them again. To apply the same static configuration after each boot-up, the PID1-programs are used: System V init executes shell scripts and binary programs, systemd parses its own conf-files (and executes programs).