DESCRIPTION¶
NetworkManager-dispatcher service is a D-Bus activated service
that runs user provided scripts upon certain changes in NetworkManager.
NetworkManager-dispatcher will execute scripts in the
/{etc,usr/lib}/NetworkManager/dispatcher.d directory or subdirectories in
alphabetical order in response to network events. Each script should be a
regular executable file owned by root. Furthermore, it must not be writable
by group or other, and not setuid.
Each script receives two arguments, the first being the interface
name of the device an operation just happened on, and second the action. For
device actions, the interface is the name of the kernel interface suitable
for IP configuration. Thus it is either VPN_IP_IFACE, DEVICE_IP_IFACE, or
DEVICE_IFACE, as applicable. For the hostname action the device name
is always "none". For connectivity-change and
dns-change it is empty.
The actions are:
pre-up
The interface is connected to the network but is not yet
fully activated. Scripts acting on this event must be placed or symlinked into
the /etc/NetworkManager/dispatcher.d/pre-up.d directory, and NetworkManager
will wait for script execution to complete before indicating to applications
that the interface is fully activated.
up
The interface has been activated.
pre-down
The interface will be deactivated but has not yet been
disconnected from the network. Scripts acting on this event must be placed or
symlinked into the /etc/NetworkManager/dispatcher.d/pre-down.d directory, and
NetworkManager will wait for script execution to complete before disconnecting
the interface from its network. Note that this event is not emitted for forced
disconnections, like when carrier is lost or a wireless signal fades. It is
only emitted when there is an opportunity to cleanly handle a network
disconnection event.
down
The interface has been deactivated.
vpn-pre-up
The VPN is connected to the network but is not yet fully
activated. Scripts acting on this event must be placed or symlinked into the
/etc/NetworkManager/dispatcher.d/pre-up.d directory, and NetworkManager will
wait for script execution to complete before indicating to applications that
the VPN is fully activated.
vpn-up
A VPN connection has been activated.
vpn-pre-down
The VPN will be deactivated but has not yet been
disconnected from the network. Scripts acting on this event must be placed or
symlinked into the /etc/NetworkManager/dispatcher.d/pre-down.d directory, and
NetworkManager will wait for script execution to complete before disconnecting
the VPN from its network. Note that this event is not emitted for forced
disconnections, like when the VPN terminates unexpectedly or general
connectivity is lost. It is only emitted when there is an opportunity to
cleanly handle a VPN disconnection event.
vpn-down
A VPN connection has been deactivated.
hostname
The system hostname has been updated. Use
gethostname(2)
to retrieve it. The interface name (first argument) is empty and no
environment variable is set for this action.
dhcp4-change
The DHCPv4 lease has changed (renewed, rebound,
etc).
dhcp6-change
The DHCPv6 lease has changed (renewed, rebound,
etc).
connectivity-change
The network connectivity state has changed (no
connectivity, went online, etc).
reapply
The connection was reapplied on the device.
dns-change
The DNS configuration has changed. This action is raised
even if NetworkManager is configured to not manage resolv.conf (for example,
via dns=none). In such case, the dispatch script can discover the DNS
configuration provided by currently active connections by looking at file
/run/NetworkManager/resolv.conf
device-add
This action is called when a connection of type generic
has the generic.device-handler property set. The property indicates the name
of a dispatcher script to be executed in directory
/{etc,usr/lib}/NetworkManager/dispatcher.d/device. Note that differently from
other actions, only one script is executed.
The script needs to perform any action needed to create the device
for the generic connection. On successful termination, the script returns
zero. Otherwise, it returns a non-zero value to indicate an error. The
script can return values to NetworkManager by writing to standard output;
each line should contain a key name followed by the equal sign '=' and a key
value. The keys understood at the moment are:
IFINDEX
Indicates the interface index of the interface created by
the script. This key is required when the script succeeds; if it is not set,
the activation will fail. The key is ignored in case of script failure.
ERROR
Specifies an error message indicating the cause of the
script failure. It is ignored when the script succeeds.
Since the dispatcher service captures stdout for parsing those
keys, anything written to stdout will not appear in the dispatcher service
journal log. Use stderr if you want to print messages to the journal (for
example, for debugging). Only the first 8KiB of stdout are considered and
among those, only the first 64 lines; the rest is ignored.
device-delete
This action is the counterpart of device-add and is
called to delete the device for a generic connection. All the aspects
described for device-add also apply to this action, with the only exception
that key IFINDEX is ignored. It is not necessary to delete the kernel
link in the handler because NetworkManager already does that; therefore the
action is useful for any additional cleanup needed.
The environment contains more information about the interface and
the connection. The following variables are available for the use in the
dispatcher scripts:
NM_DISPATCHER_ACTION
The dispatcher action like "up" or
"dhcp4-change", identical to the first command line argument. Since
NetworkManager 1.12.0.
CONNECTION_UUID
The UUID of the connection profile.
CONNECTION_ID
The name (ID) of the connection profile.
CONNECTION_DBUS_PATH
The NetworkManager D-Bus path of the connection.
CONNECTION_FILENAME
The backing file name of the connection profile (if
any).
CONNECTION_EXTERNAL
If "1", this indicates that the connection
describes a network configuration created outside of NetworkManager.
DEVICE_IFACE
The interface name of the control interface of the
device. Depending on the device type, this differs from
DEVICE_IP_IFACE. For example for ADSL devices, this could be 'atm0' or
for WWAN devices it might be 'ttyUSB0'.
DEVICE_IP_IFACE
The IP interface name of the device. This is the network
interface on which IP addresses and routes will be configured.
IP4_ADDRESS_N
The IPv4 address in the format "address/prefix
gateway", where N is a number from 0 to (# IPv4 addresses - 1). gateway
item in this variable is deprecated, use IP4_GATEWAY instead.
IP4_NUM_ADDRESSES
The variable contains the number of IPv4 addresses the
script may expect.
IP4_GATEWAY
The gateway IPv4 address in traditional numbers-and-dots
notation.
IP4_ROUTE_N
The IPv4 route in the format "address/prefix
next-hop metric", where N is a number from 0 to (# IPv4 routes -
1).
IP4_NUM_ROUTES
The variable contains the number of IPv4 routes the
script may expect.
IP4_NAMESERVERS
The variable contains a space-separated list of the DNS
servers.
IP4_DOMAINS
The variable contains a space-separated list of the
search domains.
DHCP4_<dhcp-option-name>
If the connection used DHCP for address configuration,
the received DHCP configuration is passed in the environment using standard
DHCP option names, prefixed with "DHCP4_", like
"DHCP4_HOST_NAME=foobar".
IP6_<name> and DHCP6_<name>
The same variables as for IPv4 are available for IPv6,
but the prefixes are IP6_ and DHCP6_ instead.
CONNECTIVITY_STATE
The network connectivity state, which can take the values
defined by the NMConnectivityState type, from the
org.freedesktop.NetworkManager D-Bus API: UNKNOWN, NONE, PORTAL, LIMITED or
FULL. Note: this variable will only be set for connectivity-change
actions.
In case of VPN, VPN_IP_IFACE is set, and IP4_*, IP6_* variables
with VPN prefix are exported too, like VPN_IP4_ADDRESS_0,
VPN_IP4_NUM_ADDRESSES.
The content of the user setting for the connection being activated
is also passed via environment variables. Each key is stored in a variable
with name CONNECTION_USER_ concatenated with the encoding of the key name.
The encoding works as follows:
•lowercase letters become uppercase
•uppercase letters are prefixed with an
underscore
•numbers do not change
•a dot is replaced with a double underscore
•any other character is encoded with an underscore
followed by its 3-digit octal representation
For example, key test.foo-Bar2 is stored in a variable named
CONNECTION_USER_TEST__FOO_055_BAR2.
Dispatcher scripts are run one at a time, but asynchronously from
the main NetworkManager process, and will be killed if they run for too
long. If your script might take arbitrarily long to complete, you should
spawn a child process and have the parent return immediately. Scripts that
are symbolic links pointing inside the
/etc/NetworkManager/dispatcher.d/no-wait.d/ directory are run immediately,
without waiting for the termination of previous scripts, and in parallel.
Also beware that once a script is queued, it will always be run, even if a
later event renders it obsolete. (Eg, if an interface goes up, and then back
down again quickly, it is possible that one or more "up" scripts
will be run after the interface has gone down.)