Ubuntu Manpage: netplugd — network cable hotplug management daemon

NAME

       netplugd — network cable hotplug management daemon

SYNOPSIS

       netplugd [-FP] [-c config_file] [-s script_file] [-i interface_pattern] [-p pid_file]

DESCRIPTION

netplugd is a daemon that responds to network link events from the Linux kernel, such as a network
interface losing or acquiring a carrier signal.

When an Ethernet-style network interface on a host is plugged into a powered-up switch, hub, or other
host, the two use a carrier signal to establish that the link is alive. The Linux kernel makes this
information available through its netlink(7) interface.

The netplugd daemon listens for carrier detection and loss messages from the kernel's netlink(7)
subsystem. When a carrier signal is detected on an interface, it runs a script to bring the interface
up. When carrier is lost, netplugd runs a script to bring the interface down. netplugd does not define
any policies for how to manage interfaces; it leaves that to a script, /etc/netplug.d/netplug, which is
described in “FILES” below.

You tell netplugd which interfaces it should manage by giving it a list of shell-style glob patterns,
which it matches against using the fnmatch(3) function. For example, a pattern of eth[13] will tell
netplugd to only manage eth1 and eth3, if those interfaces exist. If the interfaces are not known to the
kernel at the time you start netplugd, perhaps because they are unplugged PCMCIA network interfaces or
devices whose drivers have not yet been installed, netplugd will start to manage them as soon as they are
plugged in or their drivers are available.

OPTIONS

-F Run in the foreground; do not detach and run as a daemon. Messages are logged to stdout or
stderr, instead of using the syslog(3) mechanism. This option is useful mainly for debugging
your configuration.

-P Prevent autoprobing for interfaces. The netplugd daemon normally probes for all possible
interface names that might match the patterns you tell it to manage. This is necessary in order
to get network driver modules (the default with almost all Linux distributions) loaded and set
up, so that they can provide link status notifications to the netplugd daemon. Autoprobing
should always be safe, and doesn't take long. Disable it with caution.

-c config_file
Specify the name of a file from which to read patterns that describe the interfaces to manage.
You can provide this option multiple times to read from more than one file. If you do not
provide this option at all, netplugd will attempt to read from a default config file. If you do
not want netplugd to try to read from any real config files, you can specify /dev/null as a
config file.

-s script_file
Specify an alternative script file path, override /etc/netplug.d/netplug

-i interface_pattern
Specify a pattern that will be used to match interface names that netplugd should manage. You
can provide this option multiple times to specify multiple patterns.

-p pid_file
Write the daemon's process ID to the file pid_file. If you tell netplugd to run in the
foreground, this option is ignored.

FILES

/etc/netplug/netplugd.conf
Default config file to read, if none is specified on the command line. The config file format is
one pattern per line, with white space, empty lines, and comments starting with a # character
ignored. Patterns are standard shell-style glob patterns, e.g. "eth[0-9]".

/etc/netplug.d/netplug
The "policy" program (typically a shell script) that netplugd uses to probe for interfaces, and
to bring them up or down in response to network link events. This program is called with the
name of the interface as its first argument, and one of the following options:

in A cable was plugged in, or carrier came up. The command should bring the interface up.
The command is run asynchronously, and it should exit with status 0 on success.

out A cable was plugged out, or carrier went down. The command should bring the interface
down. The command is run asynchronously, and it should exit with status 0 on success.

probe The command should load and initialise the driver for this interface, if possible, and
bring the interface into the "up" state, so that it can generate netlink(7) events. The
command is run synchronously; it must exit with status code 0 if it succeeds, otherwise
with a non-zero exit code or signal.

/etc/init.d/netplug
The init(8) script that starts, stops, and displays status of the netplugd daemon.

AUTHOR

       netplugd was written by Bryan O'Sullivan <bos@serpentine.com>.

COPYRIGHT AND LICENSE

       Copyright 2003 PathScale, Inc.  Copyright 2003, 2004, 2005 Bryan O'Sullivan

       netplugd  is  free  software; you can redistribute it and/or modify it under the terms of the GNU General
       Public License, version 2, as published  by  the  Free  Software  Foundation.   You  are  forbidden  from
       redistributing  or modifying it under the terms of any other license, including other versions of the GNU
       General Public License.

       netplugd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;  without  even  the
       implied  warranty  of  MERCHANTABILITY  or  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
       License for more details.