Linux and UNIX Man Pages

Linux & Unix Commands - Search Man Pages

irdpd(8) [minix man page]

IRDPD(8)						      System Manager's Manual							  IRDPD(8)

irdpd - internet router discovery protocol daemon SYNOPSIS
irdpd [-bsd] [-U udp-device] [-I ip-device] [-o priority-offset] DESCRIPTION
Irdpd looks for routers. This should be a simple task, but many routers are hard to find because they do not implement the router discov- ery protocol. This daemon collects information that routers do send out and makes it available. At startup irdpd sends out several router solicitation broadcasts. A good router should respond to this with a router advertisement. If a router advertisement arrives then no more solicitations are sent. The TCP/IP server has filled its routing table with the info from the advertisement, so it now has at least one router. If the advertisement is sent by a genuine router (the sender is in the table) then the irdpd daemon goes dormant for the time the advert is valid. Routers send new adverts periodically, keeping the daemon silent. Otherwise irdpd will listen for RIP (Router Information Protocol) packets. These packets are sent between routers to exchange routing information. Irdpd uses this information to build a routing table. Every now and then a router advertisement is sent to the local host to give it router information build from the RIP packets. Lastly, if a router solicitation arrives and there is no router around that sends advertisements, then irdpd sends an advertisement to the requestor. Note that this is a direct violation of RFC1256, as no host is supposed to sent those adverts. But alas the world is not always perfect, and those adverts make booting hosts find routers quickly with this help from their brothers. (Of course, they will lose the router soon if they don't have an irdpd daemon themselves.) OPTIONS
-b Broadcast advertisements instead of sending them to the local host only. This may be used to keep (non-Minix) hosts alive on a net without adverts. -s Be silent, do not send advertisements to hosts that ask for them. -d Debug mode, tell where info is coming from and where it is sent. Debugging can also be turned on at runtime by sending signal SIGUSR1 or turned off with SIGUSR2. -o priority-offset Offset used to make the gateway's preferences collected from RIP packets look worse than those found in genuine router adverts. By default -1024. SEE ALSO
set_net_default(8), boot(8), inetd(8), nonamed(8), rarpd(8). BUGS
Under standard Minix this daemon can't listen to two both IRDP and RIP at the same time, so it starts out with IRDP. It switches over to RIP if it can't find a router, or if it threatens to lose its router. It does not switch back. Irdpd may help a host that should not be helped, i.e. if it doesn't have an irdpd daemon with RIP collecting trickery. It will make System Administrators pull out their remaining hair trying to find out why a host can access outside networks for a some time after boot, but goes blind afterwards. AUTHOR
Kees J. Bot ( IRDPD(8)

Check Out this Related Man Page

in.rdisc(1M)						  System Administration Commands					      in.rdisc(1M)

in.rdisc, rdisc - network router discovery daemon SYNOPSIS
/usr/sbin/in.rdisc [-a] [-f] [-s] [send-address] [receive-address] /usr/sbin/in.rdisc -r [-p preference] [-T interval] [send-address] [receive-address] DESCRIPTION
in.rdisc remains part of the software distribution of the Solaris Operating Environment. It is, however, not used by default. in.routed(1M) includes the functionality provided by in.rdisc. See routeadm(1M) for details of how to specify the IPV4 routing daemon. in.rdisc implements the ICMP router discovery protocol. The first form of the command is used on hosts and the second form is used on routers. in.rdisc can be invoked in either the first form (host mode) or second form (router mode). On a host, in.rdisc populates the network routing tables with default routes. On a router, advertises the router to all the hosts. Host (First Form) On a host, in.rdisc listens on the ALL_HOSTS ( multicast address for ROUTER_ADVERTISE messages from routers. The received mes- sages are handled by first ignoring those listed router addresses with which the host does not share a network. Among the remaining addresses, the ones with the highest preference are selected as default routers and a default route is entered in the kernel routing table for each one of them. Optionally, in.rdisc can avoid waiting for routers to announce themselves by sending out a few ROUTER_SOLICITATION messages to the ALL_ROUTERS ( multicast address when it is started. A timer is associated with each router address. The address will no longer be considered for inclusion in the routing tables if the timer expires before a new advertise message is received from the router. The address will also be excluded from consideration if the host receives an advertise message with the preference being maximally negative or with a lifetime of zero. Router (Second Form) When in.rdisc is started on a router, it uses the SIOCGIFCONF ioctl(2) to find the interfaces configured into the system and it starts lis- tening on the ALL_ROUTERS multicast address on all the interfaces that support multicast. It sends out advertise messages to the ALL_HOSTS multicast address advertising all its IP addresses. A few initial advertise messages are sent out during the first 30 seconds and after that it will transmit advertise messages approximately every 600 seconds. When in.rdisc receives a solicitation message, it sends an advertise message to the host that sent the solicitation message. When in.rdisc is terminated by a signal, it sends out an advertise message with the preference being maximally negative. OPTIONS
-a Accept all routers independent of the preference they have in their advertise messages. Normally, in.rdisc only accepts (and enters in the kernel routing tables) the router or routers with the highest preference. -f Run in.rdisc forever even if no routers are found. Normally, in.rdisc gives up if it has not received any advertise message after soliciting three times, in which case it exits with a non-zero exit code. If -f is not specified in the first form then -s must be specified. -r Act as a router, rather than a host. -s Send three solicitation messages initially to quickly discover the routers when the system is booted. When -s is specified, in.rdisc exits with a non-zero exit code if it can not find any routers. This can be overridden with the -f option. -p preference Set the preference transmitted in the solicitation messages. The default is zero. -T interval Set the interval between transmitting the advertise messages. The default time is 600 seconds. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWroute | +-----------------------------+-----------------------------+ SEE ALSO
in.routed(1M), routeadm(1M), ioctl(2), gateways(4), attributes(5), icmp(7P), inet(7P) Deering, S.E., editor, ICMP Router Discovery Messages, RFC 1256, Network Information Center, SRI International, Menlo Park, California, September 1991. SunOS 5.10 5 Nov 2004 in.rdisc(1M)
Man Page