isatapd(8)						      ISATAP client for Linux							isatapd(8)

NAME

       isatapd - ISATAP client for Linux

SYNOPSIS

       isatapd --help
       isatapd [ --daemon ] [ --link device ] [ options ] [ router ] [ ... ]

DESCRIPTION

       isatapd is a userspace program or daemon that sets up and maintains an ISATAP client tunnel by using the kernels ISATAP capabilities, first
       introduced with 2.6.25.

       The program will create the tunnel, periodically query the specified routers, add them to the potential router list , send periodic  router
       solicitations and parse router advertisements.  isatapd will try to keep the tunnel up and running, even if the network topology changes.

       See NOTES below for more information

OPTIONS

       -n --name name
	      Name of the tunnel interface. Default is is0.

       -l --link device
	      Tunnel  link  device.  If specified, tunnel will be restricted to that device, allowing multiple instances of isatapd with different
	      tunnels. The tunnel can only exist as long as the link device is up and has a IPv4 address configured.

	      If unspecified, the outgoing IPv4 address will be guessed for the first router and the tunnel created accordingly. The tunnel device
	      will only created, if there is a possible IPv4 source address to reach the first router.

       -m --mtu bytes
	      Sets  the MTU to value for the tunnel device, minimum is 1280. If unspecified, the kernel will choose the MTU automatically, usually
	      1480.

       -t --ttl hoplimit
	      Set the tunnel hoplimit, default is 64. Specifying 'auto' or 'inherit' will make the tunnel inherit the ttl from the linked device.

       -N --nopmtudisc
	      Disable (IPv4) Path MTU Discovery on this tunnel. For this to work --ttl has to be set to inherit. Default: do Path MTU Discovery to
	      reduce redundant fragmentation.

       -r --router router
	      Set  a  potential  router.   isatapd will resolv the hostname, add the IPv4 address to the PRL and send periodic router solicitation
	      messages. Up to 10 potential routers can be specified, the default is the unqualified domainname "isatap".

       -i --interval seconds
	      Default interval to send router solicitations. If the router lifetime is lower, the interval will be 80 of  the  router's  lifetime.
	      Can be used to force solicitations at a shorter interval.

	      Default: auto

       -D --check-dns seconds
	      Interval to perform DNS resolution of configured routers and to recreate the PRL, if necessary. Set to 0 to disable.

	      Default: 3600 sec = 1 hour

       -d --daemon
	      fork to background. No logging is available yet.

       -p --pid file
	      Store  the pid as plaintext to file. The pid file will be write-locked to prevent multiple running instances. Useful for scripts and
	      when running isatapd as a daemon.

       --user username
	      Drop privileges to this user when running the solicitation loop.

	      Default: nobody

       -v --verbose
	      increase verbosity

       -q --quiet
	      decrease verbosity

       -h --help
	      print usage

       --version
	      print version

EXIT STATUS

       On success zero is returned, otherwise a non-zero value is returned.

SIGNALS

       SIGHUP Force sending router solicitations and recreate the tunnel, if neccessary.

       SIGINT SIGTERM
	      Gracefully shut down tunnel device and terminate.

SYSLOG

       isatapd logs to stderr when run in foreground and to syslog(3), using the facility LOG_DAEMON. Verbosity can be controlled with the -v  and
       -q switches.

NOTES

       Network	data  will  be	processed by isatapd with privileges of an unprivileged user to minimize impact of bugs in the networking code. To
       create and maintain the tunnel device, root privileges are necessary.

       Whenever the tunnel link interface goes down or the source address for the local  tunnel  endpoint  changes,  the  tunnel  device  will	be
       destroyed and recreated, if possible. Note that till then your tunnel might be in a unusable state.

AUTHORS

       Sascha Hlusiak <mail@saschahlusiak.de>

       Kwong-Sang Yin <kwong-sang.yin@boeing.com>

       Fred Templin <fred.l.templin@boeing.com>

SEE ALSO

       ip(8) syslog-ng(8)

       http://www.ietf.org/rfc/rfc5214.txt

isatapd-0.9.6							November 15th, 2009							isatapd(8)