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NetworkManagerNetworkManager — network management daemon |
NetworkManager [OPTIONS...]
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.
NetworkManager-dispatcher service can execute scripts for the user in response to network events. See NetworkManager-dispatcher(8) manual.
The following options are understood:
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Print the NetworkManager software version and exit. |
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Print NetworkManager's available options and exit. |
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Do not daemonize. |
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Do not daemonize, and direct log output to the controlling terminal in addition to syslog. |
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Specify location of a PID file. The PID file is used for storing PID of the running process and prevents running multiple instances. |
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Specify file for storing state of the
NetworkManager persistently. If not specified, the default
value of |
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Specify configuration file to set up various
settings for NetworkManager. If not specified, the default
value of |
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Quit after all devices reach a stable state.
The optional |
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List plugins used to manage system-wide
connection settings. This list has preference over plugins
specified in the configuration file. See |
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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 |
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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 |
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Print the NetworkManager configuration to stdout and exit. |
udev(7) device manager is used for the network device discovery. The following property influences how NetworkManager manages the devices:
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If set to |
NetworkManager process handles the following signals:
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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 |
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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. |
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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.
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).
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.
NetworkManager home page, NetworkManager.conf(5), NetworkManager-dispatcher(8), nmcli(1), nmcli-examples(7), nm-online(1), nm-settings(5), nm-applet(1), nm-connection-editor(1), udev(7)