NETWORKMANAGER(8) Network management daemons NETWORKMANAGER(8)
NAME
NetworkManager - network management daemon
SYNOPSIS
NetworkManager [OPTIONS...]
DESCRIPTION
The NetworkManager daemon attempts to make networking configuration and
operation as painless and automatic as possible by managing the primary
network connection and other network interfaces, like Ethernet, Wi-Fi,
and Mobile Broadband devices. NetworkManager will connect any network
device when a connection for that device becomes available, unless that
behavior is disabled. Information about networking is exported via a
D-Bus interface to any interested application, providing a rich API
with which to inspect and control network settings and operation.
DISPATCHER SCRIPTS
NetworkManager-dispatcher service can execute scripts for the user in
response to network events. See NetworkManager-dispatcher(8) manual.
OPTIONS
The following options are understood:
--version | -V
Print the NetworkManager software version and exit.
--help | -h
Print NetworkManager's available options and exit.
--no-daemon | -n
Do not daemonize.
--debug | -d
Do not daemonize, and direct log output to the controlling terminal
in addition to syslog.
--pid-file | -p
Specify location of a PID file. The PID file is used for storing
PID of the running process and prevents running multiple instances.
--state-file
Specify file for storing state of the NetworkManager persistently.
If not specified, the default value of
/var/lib/NetworkManager/NetworkManager.state is used.
--config
Specify configuration file to set up various settings for
NetworkManager. If not specified, the default value of
/etc/NetworkManager/NetworkManager.conf is used with a fallback to
the older 'nm-system-settings.conf' if located in the same
directory. See NetworkManager.conf(5) for more information on
configuration file.
--configure-and-quit [initrd]
Quit after all devices reach a stable state. The optional initrd
parameter enables mode, where no processes are left running after
NetworkManager stops, which is useful for running from an initial
ramdisk on rearly boot.
--plugins
List plugins used to manage system-wide connection settings. This
list has preference over plugins specified in the configuration
file. See main.plugins setting in NetworkManager.conf(5) for
supported options.
--log-level
Sets how much information NetworkManager sends to the log
destination (usually syslog's "daemon" facility). By default, only
informational, warning, and error messages are logged. See the
section on logging in NetworkManager.conf(5) for more information.
--log-domains
A comma-separated list specifying which operations are logged to
the log destination (usually syslog). By default, most domains are
logging-enabled. See the section on logging in
NetworkManager.conf(5) for more information.
--print-config
Print the NetworkManager configuration to stdout and exit. See
NetworkManager.conf(5). This does not include connection profiles.
View them with nmcli connection.
This reads configuration files from disk. If NetworkManager is
currently running, make sure that it has the same configuration
loaded.
UDEV PROPERTIES
udev(7) device manager is used for the network device discovery. The
following property influences how NetworkManager manages the devices:
NM_UNMANAGED
If set to "1" or "true", the device is configured as unmanaged by
NetworkManager. Note that the user still can explicitly overrule
this configuration via means like nmcli device set "$DEVICE"
managed yes or "device*.managed=1" in NetworkManager.conf.
SIGNALS
NetworkManager process handles the following signals:
SIGHUP
The signal causes a reload of NetworkManager's configuration. Note
that not all configuration parameters can be changed at runtime and
therefore some changes may be applied only after the next restart
of the daemon. A SIGHUP also involves further reloading actions,
like doing a DNS update and restarting the DNS plugin. The latter
can be useful for example when using the dnsmasq plugin and
changing its configuration in /etc/NetworkManager/dnsmasq.d.
However, it also means this will shortly interrupt name resolution.
In the future, there may be further actions added. A SIGHUP means
to update NetworkManager configuration and reload everything that
is supported. Note that this does not reload connections from disk.
For that there is a D-Bus API and nmcli's reload action
SIGUSR1
The signal forces a rewrite of DNS configuration. Contrary to
SIGHUP, this does not restart the DNS plugin and will not interrupt
name resolution. When NetworkManager is not managing DNS, the
signal forces a restart of operations that depend on the DNS
configuration (like the resolution of the system hostname via
reverse DNS, or the resolution of WireGuard peers); therefore, it
can be used to tell NetworkManager that the content of resolv.conf
was changed externally. In the future, further actions may be
added. A SIGUSR1 means to write out data like resolv.conf, or
refresh a cache. It is a subset of what is done for SIGHUP without
reloading configuration from disk.
SIGUSR2
The signal has no effect at the moment but is reserved for future
use.
An alternative to a signal to reload configuration is the Reload D-Bus
call. It allows for more fine-grained selection of what to reload, it
only returns after the reload is complete, and it is guarded by
PolicyKit.
DEBUGGING
NetworkManager only configures your system. So when your networking
setup doesn't work as expected, the first step is to look at your
system to understand what is actually configured, and whether that is
correct. The second step is to find out how to tell NetworkManager to
do the right thing.
You can for example try to ping hosts (by IP address or DNS name), look
at ip link show, ip address show and ip route show, and look at
/etc/resolv.conf for name resolution issues. Also look at the
connection profiles that you have configured in NetworkManager (nmcli
connection and nmcli connection show "$PROFILE") and the configured
interfaces (nmcli device).
If that does not suffice, look at the logfiles of NetworkManager.
NetworkManager logs to syslog, so depending on your system
configuration you can call journalctl to get the logs. By default,
NetworkManager logs are not verbose and thus not very helpful for
investigating a problem in detail. You can change the logging level at
runtime with nmcli general logging level TRACE domains ALL. But usually
a better way is to collect full logs from the start, by configuring
level=TRACE in NetworkManager.conf. See NetworkManager.conf(5) manual.
Note that trace logs of NetworkManager are verbose and systemd-journald
might rate limit some lines. Possibly disable rate limiting first with
the RateLimitIntervalSec and RateLimitBurst options of journald (see
journald.conf(5) manual).
NetworkManager does not log any secrets. However, you are advised to
check whether anything private sensitive gets logged before posting.
When reporting an issue, provide complete logs and avoid modifications
(for privacy) that distort the meaning.
/VAR/LIB/NETWORKMANAGER/SECRET_KEY AND /ETC/MACHINE-ID
The identity of a machine is important as various settings depend on
it. For example, ipv6.addr-gen-mode=stable and
ethernet.cloned-mac-address=stable generate identifiers by hashing the
machine's identity. See also the connection.stable-id connection
property which is a per-profile seed that gets hashed with the machine
identity for generating such addresses and identifiers.
If you backup and restore a machine, the identity of the machine
probably should be preserved. In that case, preserve the files
/var/lib/NetworkManager/secret_key and /etc/machine-id. On the other
hand, if you clone a virtual machine, you probably want that the clone
has a different identity. There is already existing tooling on Linux
for handling /etc/machine-id (see machine-id(5)).
The identity of the machine is determined by the
/var/lib/NetworkManager/secret_key. If such a file does not exist,
NetworkManager will create a file with random content. To generate a
new identity just delete the file and after restart a new file will be
created. The file should be read-only to root and contain at least 16
bytes that will be used to seed the various places where a stable
identifier is used.
Since 1.16.0, NetworkManager supports a version 2 of secret-keys. For
such keys /var/lib/NetworkManager/secret_key starts with ASCII "nm-v2:"
followed by at least 32 bytes of random data. Also, recent versions of
NetworkManager always create such kinds of secret-keys, when the file
does not yet exist. With version 2 of the secret-key, /etc/machine-id
is also hashed as part of the generation for addresses and identifiers.
The advantage is that you can keep /var/lib/NetworkManager/secret_key
stable, and only regenerate /etc/machine-id when cloning a VM.
BUGS
Please report any bugs you find in NetworkManager at the NetworkManager
issue tracker[1].
SEE ALSO
NetworkManager home page[2], NetworkManager.conf(5), NetworkManager-
dispatcher(8), NetworkManager-wait-online.service(8), nmcli(1), nmcli-
examples(7), nm-online(1), nm-settings(5), nm-applet(1), nm-connection-
editor(1), udev(7)
NOTES
1. NetworkManager issue tracker
https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues
2. NetworkManager home page
https://networkmanager.dev
NetworkManager 1.42.4 NETWORKMANAGER(8)
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