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f5c087c8e9
Kernel does not allow to add the same route (as determined by network/plen,metric) on two different interfaces (ifindex). In case of conflict, NMRouteManager used to ignore any but the firstly added route. On the other hand, we cannot add a gateway-route, if there is no direct route to the gateway. Hence, skipping duplicate routes can mean that we skip a direct route what was necessary to add another gateway-route, which then leads to a failure to add that route. This also applies to IPv4 device routes that since recently are managed by NMRouteManager. For example, say you connect two interfaces to the same IP subnet. The route-metric can conflict if the interfaces are of the same type or if the user explicitly configured a conflict. In case of conflicts, NMRouteManager would only configure the first appearing route and skip the shadowed route on the second interface. Now we cannot configure gateway-routes on the second interface because the gateway is unreachable. There are many scenarios where this issue can happen, especially with default-routes and user-configured-routes. For example with default-routes, ip4_config_merge_and_apply() would check if the default-gateway requires an explict route and possibly add it. But then NMRouteManager might not add the route because it is shadowed by a route on an other interface. This patch solves the issue by having NMRouteManager configure shadowed routes too, similar to what NMDefaultRouteManager does. It does that by searching for an unused, non-conflicting, higher metric for the route, i.e. bump the metric by 1 until we can add it without conflict. Also note that NMRouteManager still ensures that for conflicting routes the best route sticks to the interface that configured it first. That means if you later add the conflicting route on another interface, it will be added with higher metric and the data is still routed along the first interface. |
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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.