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RTADVD(8)	       DragonFly System Manager's Manual	     RTADVD(8)

NAME

rtadvd -- router advertisement daemon

SYNOPSIS

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

DESCRIPTION

The rtadvd utility 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 con- figuration 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. The rtadvd utility also watches the routing table. If an interface direct 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 lifetimes to help the receiving hosts switch to a new prefix when renumbering. Note, how- ever, that the zero valid lifetime cannot invalidate the autoconfigured addresses at a receiving host immediately. According to the specifica- tion, 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 address should be used as the source address of a new connection. This behavior 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 sta- tus. 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 information 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). -M Specify an interface to join the all-routers site-local multicast group. By default, rtadvd tries to join the first advertising interface appeared in the command line. This option has meaning only with the -R option, which enables routing renumbering proto- col support. -R Accept router renumbering requests. If you enable it, certain IPsec setup is suggested for security reasons. On KAME-based systems, rrenumd(8) generates router renumbering request packets. 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 trans- mit 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 run- ning rtadvd. /var/run/rtadvd.dump in which rtadvd dumps its internal state.

EXIT STATUS

The rtadvd utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

rtadvd.conf(5), rrenumd(8), rtsol(8)

HISTORY

The rtadvd utility first appeared in WIDE Hydrangea IPv6 protocol stack kit.

CAVEAT

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 dis- cussion in the IETF ipng working group, all routers should rather adver- tise the messages regardless of the network topology, in order to ensure reachability. DragonFly 3.7 May 17, 1998 DragonFly 3.7