15b1304477
IP addresses, routes, TC and QDiscs are all tied to a certain interface.
So when NetworkManager manages an interface, it can be confident that
all related entires should be managed, deleted and modified by NetworkManager.
Routing policy rules are global. For that we have NMPRulesManager which
keeps track of whether NetworkManager owns a rule. This allows multiple
connection profiles to specify the same rule, and NMPRulesManager can
consolidate this information to know whether to add or remove the rule.
NMPRulesManager would also support to explicitly block a rule by
tracking it with negative priority. However that is still unused at
the moment. All that devices do is to add rules (track with positive
priority) and remove them (untrack) once the profile gets deactivated.
As rules are not exclusively owned by NetworkManager, NetworkManager
tries not to interfere with rules that it knows nothing about. That
means in particular, when NetworkManager starts it will "weakly track"
all rules that are present. "weakly track" is mostly interesting for two
cases:
- when NMPRulesManager had the same rule explicitly tracked (added) by a
device, then deactivating the device will leave the rule in place.
- when NMPRulesManager had the same rule explicitly blocked (tracked
with negative priority), then it would restore the rule when that
block gets removed (as said, currently nobody actually does this).
Note that when restarting NetworkManager, then the device may stay and
the rules kept. However after restart, NetworkManager no longer knows
that it previously added this route, so it would weakly track it and
never remove them again.
That is a problem. Avoid that, by whenever explicitly tracking a rule we
also make sure to no longer weakly track it. Most likely this rule was
indeed previously managed by NetworkManager. If this was really a rule
added by externally, then the user really should choose distinct
rule priorities to avoid such conflicts altogether.
****************** NetworkManager core daemon has moved to gitlab.freedesktop.org! git clone https://gitlab.freedesktop.org/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 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.