isatapd - ISATAP client for Linux
isatapd --help
isatapd [ --daemon ] [ --link device ] [
options ] [ router ] [ ... ]
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
- -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 or 'auto' , 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 bytes for the tunnel device, minimum is 1280. If
unspecified, 'auto' or 0, the kernel will choose the MTU, 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 or interval is 'auto' , 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
On success zero is returned, otherwise a non-zero
value is returned.
- SIGHUP
- Force sending router solicitations and recreate the tunnel, if
neccessary.
- SIGINT
SIGTERM
- Gracefully shut down tunnel device and terminate.
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.
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.
Sascha Hlusiak <mail@saschahlusiak.de>
Kwong-Sang Yin <kwong-sang.yin@boeing.com>
Fred Templin <fred.l.templin@boeing.com>