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read-only mirror of https://gitlab.freedesktop.org/NetworkManager/NetworkManager
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In the past we had NMDefaultRouteManager which would coordinate adding the default-route with identical metrics. That especially happened, when activating two devices of the same type, without explicitly specifying ipv4.route-metric. For example, with ethernet devices, the routes on both interfaces would get a metric of 100. Coordinating routes was especially necessary, because we added routes with NLM_F_EXCL flag, akin to `ip route replace`. We not only had to avoid that activating two devices in NetworkManager would result in a fight over the default-route, but more importently to preserve externally added default-routes on unmanaged interfaces. NMDefaultRouteManager would ensure that in case of duplicate metrics, that the device that activated first would keep the best default-route. It would do so by bumping the metric of the second device to find a unused metric. The bumping itself was not very important -- MDefaultRouteManager could also just not configure any default-routes that show up as second, the result would be quite similar. More important was to keep the best default-route on the first activating device until the device deactivates or a device activates that really has a better default-route.. Likewise, NMRouteManager would globally manage non-default-routes. It would not do any bumping of metrics, but it would also ensure that the routes of the device that activates first are not overwritten by a device activating later. However, the `ip route replace` approach has downsides, especially that it messes with routes on other interfaces, interfaces that are possibly not managed by NetworkManager. Another downside is, that binding a socket to an interface might not result in correct routes, because the route might just not be there (in case of NMRouteManager, which wouldn't configure duplicate routes by bumping their metric). Since commit |
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| configure.ac | ||
| CONTRIBUTING | ||
| COPYING | ||
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| MAINTAINERS | ||
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| NetworkManager.pc.in | ||
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****************** 2008-12-11: NetworkManager core daemon has moved to git.freedesktop.org! git clone git://git.freedesktop.org/git/NetworkManager/NetworkManager.git ****************** Networking that Just Works -------------------------- 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 it's 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 http://bugzilla.gnome.org and choose the NetworkManager component. Attaching the output of /var/log/messages or /var/log/daemon.log (wherever your distribution directs syslog's 'daemon' facility output) is often very helpful, and (if you can get) a working wpa_supplicant config file helps enormously.