NAME

     netplugd — network cable hotplug management daemon

SYNOPSIS

     netplugd [-FP] [-c config_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.

     -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.

SEE ALSO

     cardmgr(5), hotplug(8), ip(8), netlink(7)