in.ndpd provides both the host and router autoconfiguration components of Neighbor Discovery for IPv6 and Stateless Address Autoconfiguration for IPv6. In particular, in.ndpd implements

• router discovery;
• prefix discovery;
• parameter discovery; and
• address autoconfiguration.

• address resolution;
• neighbor unreachability detection; and
• redirect.

If the /etc/inet/ndpd.conf file does not exist or does not set the variable AdvSendAdvertisements to true for a network interface, then in.ndpd will make the node a host for that interface, that is, sending router solicitation messages and then using router advertisement messages it receives to autoconfigure the node. Note that in.ndpd only autoconfigures the addresses of global or site-local scope from the prefix advertisement.

If AdvSendAdvertisements is set to true for an interface, then in.ndpd will perform router functions on that interface, that is, sending router advertisement messages to autoconfigure the attached hosts, but not use any advertisements it receives for autoconfiguration. However, when sending advertisements, in.ndpd will use the advertisements it sends itself to autoconfigure its prefixes. For improved robustness in.ndpd stores any autoconfigured IPv6 addresses and their expiration times in state files named ndpd_state.interface that are located in the /var/inet directory. Should in.ndpd fail to find any routers, it will use the state files as a fallback, autoconfiguring those addresses if the recorded addresses have remaining lifetime. This ensures that a host that reboots faster than the routers, for example after a short power failure, will continue using the addresses that it had before the power failure.

-a

Turn off stateless address auto configuration. When set, the daemon does not autoconfigure any addresses and does not renumber any addresses.

-d

Turn on large amounts of debugging output on stdout. When set, the program runs in the foreground and stays attached to the controlling terminal.

-f  config_file

Use config_file for configuration information instead of the default /etc/inet/ndpd.conf.

-t

Turn on tracing (printing) of all sent and received packets tostdout. When set, the program runs in the foreground and stays attached to the controlling terminal.

/etc/inet/ndpd.conf

Configuration file. Not needed on a host but required on a router to enable in.ndpd to advertise autoconfiguration information to the hosts.

/var/inet/ndpd_state.interface

Contains the addresses for interface. The existence of an address in this file does not imply that the address is usable, since the address lifetime may have expired.

See attributes(5) for descriptions of the following attributes:

ifconfig(1M), ndpd.conf(4), attributes(5), icmp6(7p),ip6(7p) attributes(5)

Narten, T., Nordmark, E., Simpson, W., RFC 2461, Neighbor Discovery for IP Version 6 (IPv6), The Internet Society, December 1998.

Thomson, S., Narten, T., RFC 2462, IPv6 Stateless Address Autoconfiguration, The Internet Society, December 1998.

Receipt of a SIGHUP signal will make in.ndpd restart and reread /etc/inet/ndpd.conf.