NAME
rtadvd
—
router advertisement daemon
SYNOPSIS
rtadvd |
[-dMRs ] [-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 response 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 at all, 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. By
default, if an interface direct route is added/deleted on an advertising
interface and no static prefixes are specified by the configuration file,
rtadvd
adds/deletes the corresponding prefix to/from
its advertising list, respectively. The -s
option
may be used to disable this behavior. Moreover, if the status of an
advertising interface changes, rtadvd
will start or
stop sending router advertisements according to the latest status.
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 information and link
MTU. Thus, rtadvd
can be invoked if router lifetime
is explicitly set to zero on every advertising interface.
The command line options are:
-c
configfile- Specify an alternate location, configfile, for the configuration file. By default, /etc/rtadvd.conf is used.
-d
- Do not daemonize. If this option is specified,
rtadvd
will run in the foreground and log to stderr. -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 option has meaning only with the-R
option, which enables routing renumbering protocol support. -R
- Accept router renumbering requests. If you enable it, an
ipsec(4) 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 configured prefixes, if any, will be advertised.
Upon receipt of signal SIGUSR1
,
rtadvd
will dump the current internal state into
syslog(3).
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 RFC 2461
6.2.5).
FILES
- /etc/rtadvd.conf
- The default configuration file.
- /var/run/rtadvd.pid
- Contains the PID of the currently running
rtadvd
.
EXIT STATUS
The rtadvd
utility exits 0 on
success, and >0 if an error occurs.
SEE ALSO
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 later discussion in the
IETF IPng working group, all routers should rather advertise the messages
regardless of the network topology, in order to ensure reachability.