NetworkManager is a software to provide an API for configuring the network on Linux. It aims to make configuration simple and reliable.
A new NetworkManager version 1.28.0 was released today, on 6th December 2020.
Alice wants to try the latest NetworkManager release.
1.28 was already in release candidate phase for several weeks. That is longer than usual or planned, but there were some issues related to DNS which delayed the release. In the future, we should do a better job at sticking to more regular release schedules.
See the NEWS file for what is new and find the release tarball at the GNOME download page.
This release introduces no big features, but instead there are a lot of small fixes and improvements. I only would like to highlight two points that are more important to developers and maintainers:
Fixes for building NetworkManager with LTO. Building with Link Time Optimization tends to reveal issues, especially because we want NetworkManager to build without emitting compiler warnings. Now that Fedora 33 enables LTO by default, we fixed some remaining issues and have tests that continuously check that the build works.
We now reformatted our entire C source code with clang-format. The advantage is that our coding style is now governed by the code formatter and there is no more need to argue about trivialities. In particular we now use spaces for indentation, contrary to before, when tabs were used for indentation and spaces for horizontal alignment. Such so called “smart tabs” were cumbersome for contributors to get right, also because editors don’t support that style well. The downside is that this introduces a huge source code diff between 1.26 and 1.28 and makes backporting code to 1.26 harder.
NetworkManager is a software to provide an API for configuring the network on Linux. It aims to make configuration simple and reliable.
A new NetworkManager version 1.26.0 was released today.
Speedy has already upgraded to the latest version.
See the NEWS file for what is new and find the release tarball at the GNOME download page.
New manual pages nm-settings-nmcli and nm-settings-dbus. NetworkManager is all about the API that it provides. And this API is mostly about connection profiles. Depending on whether you use nmcli, D-Bus, keyfile or ifcfg-rh files, the properties of a profile are handled slightly different. For example, in nmcli all properties are strings, but on D-Bus they are structured data. So we also need different documentation. For that, we have now the manual pages nm-settings-dbus, nm-settings-nmcli, nm-settings-keyfile and nm-settings-ifcfg-rh.
Match profiles by device driver, PCI address and kernel command line. Connection profiles can be restricted to a certain device (interface). Commonly the interface name or the permanent MAC address can be specified. Since 1.26.0 there are two new matches: by device driver and by the device path. The device path essentially corresponds to the PCI address of the interface. Also, you can match a profile based on the kernel command line. That means, a profile will only be usable, if the kernel command line is as specified. For that, there are 3 new properties. In nmcli, they are called match.driver, match.path, and match.kernel-command-line. See the nm-settings-nmcli manual for details.
nm-cloud-setup now supports Google Compute Engine (GCE). nm-cloud-setup is a tool that automatically configures the network when running in a cloud environment. It already supported Amazon EC2 cloud and got support for Google Compute Engine (GCE).
Support for ethtool settings for coalesce and ring options. NetworkManager now supports ethtool coalesce and ring options in addition to offload features. For that, configure the ethtool properties like ethtool.coalesce-tx-frames.
Also, NetworkManager now restores the previous ethtool auto-negotiations settings when deactivating a profile. That is important, because with the wrong ethernet speed settings the link will have no carrier.
nmcli now colors profiles for externally configured devices differently. When a device is configured outside of NetworkManager, then NetworkManager creates an in-memory profile to represent that the device is connected. But it does not touch the device in any way, so these devices and profiles are special. This is often a cause for confusion. Now nmcli color codes these settings differently.
NetworkManager is a tool to configure the network on a Linux host. I am a NetworkManager developer and work at Red Hat. In my opinion the biggest value it provides is the API. That is what makes NetworkManager unique among other network configuration projects. Here is why.
Fleur and Eliška use NetworkManager on all their in-house production servers.
Configuring the Network
To configure the local network on the host, you need a stateful process.
Configuring networking means to setup the Linux kernel and user space so that applications can use the network. This involves setting up network interfaces, addresses and routes, DNS and the system’s hostname, and more. For most scenarios a stateful service is necessary to monitor and re-configure the system. This is for example the case for DHCP (ISC’s dhclient), Wi-Fi (wpa_supplicant), IPv6 SLAAC (kernel itself or a user space daemon), bluetooth (bluez), ppp (pppd), and more. For example, if you write a shell script to configure a networking interface with DHCP, it needs to spawn a manager deamon like ISC’s dhclient or dhcpcd.
Today we have various software that aims to manage networking exhaustively. We have NetworkManager, which is a freedesktop.org project. There is also ConnMan, netctl (on ArchLinux), systemd-networkd, wicd (unmaintained), wicked (on SUSE). Any of these will work well to setup networking on your machine.
Providing an API for other Tools
NetworkManager is more than just a tool to configure the network. Its main purpose is to provide an API for other applications.
Did you wonder why GNOME or KDE only has UI integration with NetworkManager? NetworkManager was created from the start as a configuration daemon that serves the needs of applications, independent from the UI. It is ahead of any other solution providing such an API, and that is why desktop environments integrate with it. It fits the requirements like no other. Most alternatives mentioned above don’t even have such an API as their explicit goal. Their focus is to configure the network. Of course, every program that is usable will have some form of API and a manner how to use it. But such APIs are often targeted directly towards a human, towards a user who edits a file, who invokes an ad-hoc command and who is around to react to with failures.
NetworkManager’s API aims to be used by other programs, the clients of NetworkManager. Some of these clients (GUIs) may directly target a human end user too. Or they provide integration with OpenStack or OpenShift, where the human administrator is much more detached from the host. When no human is around, it becomes critical that the current state of the system can be determined programmatically. The API is not only for configuration actions, but also to determine the current state of the system.
Generalist and Featureful
NetworkManager is a generalist and featureful and complex.
When your application relies on NetworkManager, then NetworkManager must be at least as portable as your application. That means, NetworkManager must be suitable for a wide range of environments and not only for the desktop. NetworkManager works well on the phone, the server, in a container, on a notebook and on a workstation. Likewise, NetworkManager must support a whole lot of use cases, technologies and features. The API must be powerful and ubiquitous. If there are shortcomings, then these problems are supposed to be fixable and should be fixed. Running NetworkManager on your phone or in your container is not out of scope, it is something that is supposed to work well and what is an explicit goal.
NetworkManager may not be the optimal solution in every scenario, yet. For example, on a BGP router with thousands of routes, there are still performance issues. Or running inside a container doesn’t work well with macvlan devices. Or NetworkManager running a DHCP server is simple but not very flexible. But most scenarios that you imagine are scenarios where NetworkManager wants to excel. The Linux kernel itself is the prime example of the benefits of being a generalist, and NetworkManager is also one.
This means NetworkManager is not a simple piece of software. But its complexity is there to provide features for other applications, so they themselves can be simpler. Solving hard problems once.
Integration of Tools
Using NetworkManager API allows the integration of tools.
Whether you use nmcli or nmtui on the command line, Cockpit, the GUIs, or Ansible, they all are just front ends for the same underlying configuration. And of course, you can write your own applications that uses NetworkManager’s API, and your application will naturally integrate with these other tools.
Wherever you have NetworkManager, it works and behaves the same. On RHEL and Fedora, you configure a server and the workstation using the same tools. Most Linux distributions provide NetworkManager. If you know how to configure NetworkManager on Ubuntu, you know how to configure networking on Fedora, too.
What’s Next?
NetworkManger also has issues and lacking features. Some people dislike it for being too large or complex, think it is not stable, or not suitable for anything except the desktop. NetworkManager is software, and like every software could be replaced by another piece of software. Should we instead replace it with some hypothetical, future alternative? I believe that it will be significantly simpler to incrementally improve NetworkManager, than to throw it away and start over.
In my opinion, the majority of shortcomings we face in free software comes down to lack of contributors and people. Under such circumstances, the solution for a problem is not to provide more alternatives, but to focus on making one solution work well.
One current area of focus is to integrate with Openstack, Openshift, CoreOS and dracut. I am also excited about the prospect of running NetworkManager on phones, like with UBPorts or Librem5.
NetworkManager is an active free software project. Let’s work together and run NetworkManager everywhere.
