rtadvd(8)

NAME

rtadvd - router advertisement daemon

SYNOPSIS

rtadvd [-dDfMRs] [-c configfile] interface ...

DESCRIPTION

rtadvd sends router advertisement packets to the specified

interfaces.

The program will daemonize itself on invocation. It will

then send
router advertisement packets periodically, as well as in re

sponse to
router solicitation messages sent by end hosts.

Router advertisements can be configured on a per-interface

basis, as
described in rtadvd.conf(5).

If there is no configuration file entry for an interface, or

if the configuration file does not exist altogether, rtadvd sets all

the parameters
to their default values. In particular, rtadvd reads all

the interface
routes from the routing table and advertises them as on-link

prefixes.

rtadvd also watches the routing table. If an interface di

rect route is
added on an advertising interface and no static prefixes are

specified by
the configuration file, rtadvd adds the corresponding prefix

to its
advertising list.

Similarly, when an interface direct route is deleted, rtadvd

will start
advertising the prefixes with zero valid and preferred life

times to help
the receiving hosts switch to a new prefix when renumbering.

Note, however, that the zero valid lifetime cannot invalidate the au

toconfigured
addresses at a receiving host immediately. According to the

specification, the host will retain the address for a certain period,

which will
typically be two hours. The zero lifetimes rather intend to

make the
address deprecated, indicating that a new non-deprecated ad

dress should
be used as the source address of a new connection. This be

havior will
last for two hours. Then rtadvd will completely remove the

prefix from
the advertising list, and succeeding advertisements will not

contain the
prefix information.

Moreover, if the status of an advertising interface changes,

rtadvd will
start or stop sending router advertisements according to the

latest status.

The -s option may be used to disable this behavior; rtadvd

will not watch
the routing table and the whole functionality described

above will be
suppressed.

Basically, hosts MUST NOT send Router Advertisement messages

at any time
(RFC 2461, Section 6.2.3). However, it would sometimes be

useful to
allow hosts to advertise some parameters such as prefix in

formation and
link MTU. Thus, rtadvd can be invoked if router lifetime is

explicitly
set zero on every advertising interface.

The command line options are:

-c Specify an alternate location, configfile, for the

configuration

file. By default, /etc/rtadvd.conf is used.

-d Print debugging information.

-D Even more debugging information is printed.

-f Foreground mode (useful when debugging). Log mes

sages will be

dumped to stderr when this option is specified.

-M Specify an interface to join the all-routers site

local multicast

group. By default, rtadvd tries to join the first

advertising
interface appearing on the command line. This op

tion has meaning
only with the -R option, which enables routing

renumbering protocol support.

-R Accept router renumbering requests. If you enable

it, certain

IPsec setup is suggested for security reasons. This

option is
currently disabled, and is ignored by rtadvd with a

warning message.

-s Do not add or delete prefixes dynamically. Only

statically con

figured prefixes, if any, will be advertised.

Upon receipt of signal SIGUSR1, rtadvd will dump the current

internal
state into /var/run/rtadvd.dump.

Use SIGTERM to kill rtadvd gracefully. In this case, rtadvd

will transmit router advertisement with router lifetime 0 to all the

interfaces (in
accordance with RFC2461 6.2.5).

RETURN VALUES

The rtadvd program exits 0 on success, and >0 on failures.

FILES

/etc/rtadvd.conf The default configuration

file.
/var/run/rtadvd.pid contains the pid of the

currently run

ning rtadvd.

/var/run/rtadvd.dump The file in which rtadvd

dumps its

internal state.

SEE ALSO

rtadvd.conf(5), rtsol(8)

HISTORY

The rtadvd command first appeared in the WIDE Hydrangea IPv6

protocol
stack kit.

BUGS

There used to be some text that recommended users not to let

rtadvd
advertise Router Advertisement messages on an upstream link

to avoid
undesirable icmp6(4) redirect messages. However, based on

the later discussion in the IETF ipng working group, all routers should

rather advertise the messages regardless of the network topology, in or

der to ensure
reachability.

BSD May 17, 1998

BSD