70060d570b
When serializing setting properties to GVariant/D-Bus, we usually
omit values that are set to the default. That is done by libnm(-core),
so it happens both on the daemon and client side. That might be
useful to avoid a large number of properties on D-Bus.
Before changing the default value for "ipv6.addr-gen-mode" ([1]), we
would not serialize the previous default value ("stable-privacy").
Now we would serialize the new default value ("default). This change
causes problems.
Scenario 1: have a profile in the daemon with "ipv6.addr-gen-mode=stable-privacy",
have an older daemon version before [1] and a newer client after [1]. Result:
The daemon exposes the profile on D-Bus without the addr-gen-mode
field (because it's the default). To the client, that is interpreted
differently, as "ipv6.addr-gen-mode=default". This is already somewhat
a problem.
More severe is when modifying the profile, the client would now serialize
the value "default" on D-Bus, which the older daemon rejects as invalid.
That means, you could not modify the profile, unless also resetting
addr-gen-mode to "stable-privacy" or "eui64".
You can imagine other scenarios where either the daemon or the client is
before/after change [1] and the addr-gen-mode is set to either "default"
or "stable-privacy". Depending on what scenario you look, that can either be
good or bad.
Scenario 1 is pretty bad, because it means `dnf upgrade NetworkManager
&& nmcli connection modify ...` will fail (if the daemon was not
restated). So try to fix Scenario 1, by also not serializing the new
default value on D-Bus. Of course, some of the scenarios will get
different problems, by exacerbating one side misunderstanding the actually
set value and interpreting a missing value on D-Bus wrongly. But those
problems are likely less severe.
In case both client and daemon are older/newer than [1], it doesn't
matter either way. The problem happens with different version and is
caused by a change of the default value.
[1]
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| data | ||
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| examples | ||
| introspection | ||
| m4 | ||
| man | ||
| po | ||
| src | ||
| tools | ||
| vapi | ||
| .clang-format | ||
| .dir-locals.el | ||
| .git-blame-ignore-revs | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
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| .mailmap | ||
| .triage-policies.yml | ||
| AUTHORS | ||
| autogen.sh | ||
| ChangeLog | ||
| config-extra.h.meson | ||
| config-extra.h.mk | ||
| config.h.meson | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| COPYING.GFDL | ||
| COPYING.LGPL | ||
| linker-script-binary.ver | ||
| linker-script-devices.ver | ||
| linker-script-settings.ver | ||
| lsan.suppressions | ||
| MAINTAINERS | ||
| MAINTAINERS.md | ||
| Makefile.am | ||
| Makefile.examples | ||
| Makefile.glib | ||
| Makefile.vapigen | ||
| meson.build | ||
| meson_options.txt | ||
| NEWS | ||
| README.md | ||
| RELICENSE.md | ||
| TODO | ||
| valgrind.suppressions | ||
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.