119 lines
3.7 KiB
Groff
119 lines
3.7 KiB
Groff
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IRDPD(8) Minix Programmer's Manual IRDPD(8)
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NAME
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irdpd - internet router discovery protocol daemon
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SYNOPSIS
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irdpd [-bsd] [-U udp-device] [-I ip-device] [-o priority-offset]
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DESCRIPTION
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Irdpd looks for routers. This should be a simple task, but many routers
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are hard to find because they do not implement the router discovery
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protocol. This daemon collects information that routers do send out and
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makes it available.
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At startup irdpd sends out several router solicitation broadcasts. A
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good router should respond to this with a router advertisement.
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If a router advertisement arrives then no more solicitations are sent.
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The TCP/IP server has filled its routing table with the info from the
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advertisement, so it now has at least one router. If the advertisement
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is sent by a genuine router (the sender is in the table) then the irdpd
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daemon goes dormant for the time the advert is valid. Routers send new
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adverts periodically, keeping the daemon silent.
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Otherwise irdpd will listen for RIP (Router Information Protocol)
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packets. These packets are sent between routers to exchange routing
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information. Irdpd uses this information to build a routing table.
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Every now and then a router advertisement is sent to the local host to
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give it router information build from the RIP packets.
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Lastly, if a router solicitation arrives and there is no router around
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that sends advertisements, then irdpd sends an advertisement to the
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requestor. Note that this is a direct violation of RFC1256, as no host
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is supposed to sent those adverts. But alas the world is not always
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perfect, and those adverts make booting hosts find routers quickly with
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this help from their brothers. (Of course, they will lose the router
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soon if they don't have an irdpd daemon themselves.)
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OPTIONS
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-b Broadcast advertisements instead of sending them to the local host
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only. This may be used to keep (non-Minix) hosts alive on a net
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without adverts.
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-s Be silent, do not send advertisements to hosts that ask for them.
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-d Debug mode, tell where info is coming from and where it is sent.
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Debugging can also be turned on at runtime by sending signal SIGUSR1
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or turned off with SIGUSR2.
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1
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IRDPD(8) Minix Programmer's Manual IRDPD(8)
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-o priority-offset
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Offset used to make the gateway's preferences collected from RIP
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packets look worse than those found in genuine router adverts. By
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default -1024.
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SEE ALSO
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set_net_default(8), boot(8), inetd(8), nonamed(8), rarpd(8).
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BUGS
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Under standard Minix this daemon can't listen to two both IRDP and RIP at
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the same time, so it starts out with IRDP. It switches over to RIP if it
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can't find a router, or if it threatens to lose its router. It does not
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switch back.
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Irdpd may help a host that should not be helped, i.e. if it doesn't have
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an irdpd daemon with RIP collecting trickery. It will make System
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Administrators pull out their remaining hair trying to find out why a
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host can access outside networks for a some time after boot, but goes
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blind afterwards.
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AUTHOR
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Kees J. Bot (kjb@cs.vu.nl)
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