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NetworkManager core daemon has moved to gitlab.freedesktop.org!

git clone https://gitlab.freedesktop.org/NetworkManager/NetworkManager.git

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Networking that Just Works

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NetworkManager attempts to keep an active network connection available at all

times.  The point of NetworkManager is to make networking configuration and

setup as painless and automatic as possible.  NetworkManager is intended to

replace default route, replace other routes, set IP addresses, and in general

configure networking as NM sees fit (with the possibility of manual override as

necessary).  In effect, the goal of NetworkManager is to make networking Just

Work with a minimum of user hassle, but still allow customization and a high

level of manual network control.  If you have special needs, we'd like to hear

about them, but understand that NetworkManager is not intended for every

use-case.

NetworkManager will attempt to keep every network device in the system up and

active, as long as the device is available for use (has a cable plugged in,

the killswitch isn't turned on, etc).  Network connections can be set to

'autoconnect', meaning that NetworkManager will make that connection active

whenever it and the hardware is available.

"Settings services" store lists of user- or administrator-defined "connections",

which contain all the settings and parameters required to connect to a specific

network.  NetworkManager will _never_ activate a connection that is not in this

list, or that the user has not directed NetworkManager to connect to.

How it works:

The NetworkManager daemon runs as a privileged service (since it must access

and control hardware), but provides a D-Bus interface on the system bus to

allow for fine-grained control of networking.  NetworkManager does not store

connections or settings, it is only the mechanism by which those connections

are selected and activated.

To store pre-defined network connections, two separate services, the "system

settings service" and the "user settings service" store connection information

and provide these to NetworkManager, also via D-Bus.  Each settings service

can determine how and where it persistently stores the connection information;

for example, the GNOME applet stores its configuration in GConf, and the system

settings service stores its config in distro-specific formats, or in a distro-

agnostic format, depending on user/administrator preference.

A variety of other system services are used by NetworkManager to provide

network functionality: wpa_supplicant for wireless connections and 802.1x

wired connections, pppd for PPP and mobile broadband connections, DHCP clients

for dynamic IP addressing, dnsmasq for proxy nameserver and DHCP server

functionality for internet connection sharing, and avahi-autoipd for IPv4

link-local addresses.  Most communication with these daemons occurs, again,

via D-Bus.

Why doesn't my network Just Work?

Driver problems are the #1 cause of why NetworkManager sometimes fails to

connect to wireless networks.  Often, the driver simply doesn't behave in a

consistent manner, or is just plain buggy.  NetworkManager supports _only_

those drivers that are shipped with the upstream Linux kernel, because only

those drivers can be easily fixed and debugged.  ndiswrapper, vendor binary

drivers, or other out-of-tree drivers may or may not work well with

NetworkManager, precisely because they have not been vetted and improved by the

open-source community, and because problems in these drivers usually cannot

be fixed.

Sometimes, command-line tools like 'iwconfig' will work, but NetworkManager will

fail.  This is again often due to buggy drivers, because these drivers simply

aren't expecting the dynamic requests that NetworkManager and wpa_supplicant

make.  Driver bugs should be filed in the bug tracker of the distribution being

run, since often distributions customize their kernel and drivers.

Sometimes, it really is NetworkManager's fault.  If you think that's

the case, please file a bug at:

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues

Attaching NetworkManager debug logs from the journal (or wherever your

distribution directs syslog's 'daemon' facility output, as

/var/log/messages or /var/log/daemon.log) is often very helpful, and

(if you can get) a working wpa_supplicant config file helps

enormously.  See the logging section of file

contrib/fedora/rpm/NetworkManager.conf for how to enable debug logging

in NetworkManager.