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ROUTED(1M)							    ROUTED(1M)

NAME    [Toc]    [Back]

     routed - network RIP and router discovery routing daemon

SYNOPSIS    [Toc]    [Back]

     /usr/etc/routed [-sqdghmpAtv] [-T tracefile]
	  [-F net[/mask][,metric]] [-P parms]

DESCRIPTION    [Toc]    [Back]

     Routed is a dameon	invoked	at boot	time to	manage the network routing
     tables.  It uses Routing Information Protocol, RIPv1 (RFC 1058), RIPv2
     (RFC 1723), and Internet Router Discovery Protocol	(RFC 1256) to maintain
     the kernel	routing	table.	The RIPv1 protocol is based on the reference
     4.3BSD daemon.

     It	listens	on the udp(7P) socket for the route service (see services(4))
     for Routing Information Protocol packets.	It also	sends and receives
     multicast Router Discovery	ICMP messages.	If the host is a router,
     routed periodically supplies copies of its	routing	tables to any directly
     connected hosts and networks.  It also advertise or solicits default
     routes using Router Discovery ICMP	messages.

     When started (or when a network interface is later	turned on), routed
     uses an AF_ROUTE address family facility to find those directly connected
     interfaces	configured into	the system and marked "up".  It	adds necessary
     routes for	the interfaces to the kernel routing table.  Soon after	being
     first started, and	provided there is at least one interface on which RIP
     has not been disabled, routed deletes all pre-existing non-static routes
     in	kernel table.  Static routes in	the kernel table are preserved and
     included in RIP responses if they have a valid RIP	metric (see

     If	more than one interface	is present (not	counting the loopback
     interface), it is assumed that the	host should forward packets among the
     connected networks.  After	transmitting a RIP request and Router
     Discovery Advertisements or Solicitations on a new	interface, the daemon
     enters a loop, listening for RIP request and response and Router
     Discovery packets from other hosts.

     When a request packet is received,	routed formulates a reply based	on the
     information maintained in its internal tables.  The response packet
     generated contains	a list of known	routes,	each marked with a "hop	count"
     metric (a count of	16 or greater is considered "infinite").  Advertised
     metrics reflect the metric	associated with	interface (see ifconfig(1M)),
     so	setting	the metric on an interface is an effective way to steer

     Responses do not include routes with a first hop on the requesting
     network to	implement in part split-horizon.  Requests from	query programs
     such as rtquery(1M) are answered with the complete	table.

									Page 1

ROUTED(1M)							    ROUTED(1M)

     The routing table maintained by the daemon	includes space for several
     gateways for each destination to speed recovery from a failing router.
     RIP response packets received are used to update the routing tables
     provided they are from one	of the several currently recognized gateways
     or	advertise a better metric than at least	one of the existing gateways.

     When an update is applied,	routed records the change in its own tables
     and updates the kernel routing table if the best route to the destination
     changes.  The change in the kernel	routing	table is reflected in the next
     batch of response packets sent.  If the next response is not scheduled
     for a while, a flash update response containing only recently changed
     routes is sent.

     In	addition to processing incoming	packets, routed	also periodically
     checks the	routing	table entries.	If an entry has	not been updated for 3
     minutes, the entry's metric is set	to infinity and	marked for deletion.
     Deletions are delayed until the route has been advertised with an
     infinite metric to	insure the invalidation	is propagated throughout the
     local internet.  This is a	form of	poison reverse.

     Routes in the kernel table	that are added or changed as a result of ICMP
     Redirect messages are deleted after a while to minimize black-holes.
     When a TCP	connection suffers a timeout, the kernel tells routed, which
     deletes all redirected routes through the gateway involved, advances the
     age of all	RIP routes through the gateway to allow	an alternate to	be
     chosen, and advances of the age of	any relevant Router Discovery Protocol
     default routes.

     Hosts acting as internetwork routers gratuitously supply their routing
     tables every 30 seconds to	all directly connected hosts and networks.
     These RIP responses are sent to the broadcast address on nets that
     support broadcasting, to the destination address on point-to-point	links,
     and to the	router's own address on	other networks.	 If RIPv2 is enabled,
     multicast packets are sent	on interfaces that support multicasting.

     If	no response is received	on a remote interface, if there	are errors
     while sending responses, or if there are more errors than input or	output
     (see netstat(1M)),	then the cable or some other part of the interface is
     assumed to	be disconnected	or broken, and routes are adjusted

     The Internet Router Discovery Protocol is handled similarly.  When	the
     daemon is supplying RIP routes, it	also listens for Router	Discovery
     Solicitations and sends Advertisements.  When it is quiet and listening
     to	other RIP routers, it sends Solicitations and listens for
     Advertisements.  If it receives a good Advertisement and it is not
     multi-homed, it stops listening for broadcast or multicast	RIP responses.
     It	tracks several advertising routers to speed recovery when the
     currently chosen router dies.  If all discovered routers disappear, the
     daemon resumes listening to RIP responses.	 It continues listen to	RIP
     while using Router	Discovery if multi-homed to ensure all interfaces are

									Page 2

ROUTED(1M)							    ROUTED(1M)

     The Router	Discovery standard requires that advertisements	have a default
     "lifetime"	of 30 minutes.	That means should something happen, a client
     can be without a good route for 30	minutes.  It is	a good idea to reduce
     the default to 45 seconds using "-P rdisc_interval=45" on the command
     line or "rdisc_interval=45" in the	/etc/gateways file.

     While using Router	Discovery (which happens by default when the system
     has a single network interface and	a Router Discovery Advertisement is
     received),	there is a single default route	and a variable number of
     redirected	host routes in the kernel table.  On a host with more than one
     network interface,	this default route will	be via only one	of the
     interfaces.  Thus,	multi-homed hosts running with -q might	need no_rdisc
     described below.

     See the pm_rdisc facility described below to support "legacy" systems
     that can handle neither RIPv2 nor Router Discovery.

     By	default, neither Router	Discovery advertisements nor solicitations are
     sent over point to	point links (e.g. PPP).	 The netmask associated	with
     point-to-point links (such	as SLIP	or PPP,	with the IFF_POINTOPOINT flag)
     is	used by	routed to infer	the netmask used by the	remote system when
     RIPv1 is used.

     Routed is started during system initialization from /etc/init.d/network
     using site-dependent options and arguments	in the file
     /etc/config/routed.options.  The options are:

     -s	  this option forces routed to supply routing information.  This is
	  the default if multiple network interfaces are present on which RIP
	  or Router Discovery have not been disabled, and if the kernel	switch

     -q	  is the opposite of the -s option.  This is the default when only one
	  interface is present.

     -d	  Do not run in	the background.	 This option is	meant for interactive
	  use -	do not put it in the routed.options file.

     -g	  This flag is used on internetwork routers to offer a route to	the
	  "default" destination.  It is	equivalent to "-F 0/0,1" and is
	  present mostly for historical	reasons.  A better choice is
	  "-P pm_rdisc"	on the command line or pm_rdisc	in the /etc/gateways
	  file.	 since a larger	metric will be used, reducing the spread of
	  the potentially dangerous default route.  This is typically used on
	  a gateway to the Internet, or	on a gateway that uses another routing
	  protocol whose routes	are not	reported to other local	routers.
	  Notice that because a	metric of 1 is used, this feature is
	  dangerous.  It is more commonly accidentally used to create chaos
	  with routing loop than to solve problems.

									Page 3

ROUTED(1M)							    ROUTED(1M)

     -h	  This causes host or point-to-point routes to not be advertised,
	  provided there is a network route going the same direction.  That is
	  a limited kind of aggregation.  This option is useful	on gateways to
	  ethernets that have other gateway machines connected with point-topoint
	links such as SLIP.

     -m	  This causes the machine to advertise a host or point-to-point	route
	  to its primary interface.  It	is useful on multi-homed machines such
	  as NFS servers.  This	option should not be used except when the cost
	  of the host routes it	generates is justified by the popularity of
	  the server.  It is effective only when the machine is	supplying
	  routing information, because there is	more than one interface.  The
	  -m option overrides the -q option to the limited extent of
	  advertising the host route.

     -A	  do not ignore	RIPv2 authentication if	we do not care about RIPv2
	  authentication.  This	option is required for conformance with	RFC
	  1723,	However, it makes no sense and breaks using RIP	as a discovery
	  protocol to ignore all RIPv2 packets that carry authentication when
	  this machine does not	care about authentication.

     -t	  increases the	debugging level, which causes more information to be
	  logged on the	tracefile specified with -T or standard	out.  The
	  debugging level can be increased or decreased	with the SIGUSR1 or
	  SIGUSR2 signals, or with the rtquery command.

     -v	  displays and logs the	version	of daemon.

     -T	tracefile
	  increases the	debugging level	to at least 1 and causes debugging
	  information to be appended to	the trace file.	 Note that because of
	  security concerns, it	is wisest to not run routed routinely with
	  tracing directed to a	file.

     -F	net[/mask][=metric]
	  minimize routes in transmissions via interfaces with addresses that
	  match	net/mask, and synthesizes a default route to this machine with
	  the metric.  The intent is to	reduce RIP traffic on slow, point-topoint
	links such as PPP links	by replacing many large	UDP packets of
	  RIP information with a single, small packet containing a "fake"
	  default route.  If metric is absent, a value of 14 is	assumed	to
	  limit	the spread of the "fake" default route.

	  This is a dangerous feature that when	used carelessly	can cause
	  routing loops.  Notice also that more	than one interface can match
	  the specified	network	number and mask.  See also -g.

     -P	parms
	  is equivalent	to adding the parameter	line parms to the
	  /etc/gateways	file.

									Page 4

ROUTED(1M)							    ROUTED(1M)

     Any other argument	supplied is interpreted	as the name of a file in which
     routed's actions should be	logged.	 It is better to use -T	instead	of
     appending the name	of the trace file to the command.

     routed also supports the notion of	"distant" passive or active gateways.
     When routed is started, it	reads the file /etc/gateways to	find such
     distant gateways which may	not be located using only information from a
     routing socket, to	discover if some of the	local gateways are passive,
     and to obtain other parameters.  Gateways specified in this manner	should
     be	marked passive if they are not expected	to exchange routing
     information, while	gateways marked	active should be willing to exchange
     RIP packets.  Routes through passive gateways are installed in the
     kernel's routing tables once upon startup and are not included in
     transmitted RIP responses.

     Distant active gateways are treated like network interfaces.  RIP
     responses are sent	to the distant active gateway.	If no responses	are
     received, the associated route is deleted from the	kernel table and RIP
     responses advertised via other interfaces.	 If the	distant	gateway
     resumes sending RIP responses, the	associated route is restored.

     Such gateways can be useful on media that do not support broadcasts or
     multicasts	but otherwise act like classic shared media like Ethernets
     such as some ATM networks.	 One can list all RIP routers reachable	on the
     ATM network in /etc/gateways with a series	of "host" lines.  Note that it
     is	usually	desirable to use RIPv2 in such situations to avoid generating
     lists of inferred host routes.

     Gateways marked external are also passive,	but are	not placed in the
     kernel routing table nor are they included	in routing updates.  The
     function of external entries is to	indicate that another routing process
     will install such a route if necessary, and that alternate	routes to that
     destination should	not be installed by routed.  Such entries are only
     required when both	routers	may learn of routes to the same	destination.

     The /etc/gateways file is comprised of a series of	lines, each in one of
     the following two formats or consist of parameters	described later.
     Blank lines and lines starting with '#' are comments.

     net Nname[/mask] gateway Gname metric value {passive|active|external}
     host Hname	      gateway Gname metric value {passive|active|external}

     Nname or Hname is the name	of the destination network or host.  It	may be
     a symbolic	network	name or	an Internet address specified in "dot"
     notation (see inet(3N)).  (If it is a name, then it must either be
     defined in	/etc/networks or /etc/hosts, or	name service must have been
     started before routed.)  mask is an optional number between 1 and 32
     indicating	the netmask associated with Nname.

     Gname is the name or address of the gateway to which RIP responses	should
     be	forwarded.  Value is the hop count to the destination host or network.
     "host hname" is equivalent	to "net	nname/32".

									Page 5

ROUTED(1M)							    ROUTED(1M)

     One of the	keywords passive, active or external must be present to
     indicate whether the gateway should be treated as passive or active (as
     described above), or whether the gateway is external to the scope of the
     RIP protocol.

     As	can be seen when debugging is turned on	with such lines	create
     psuedo-interfaces.	 To set	parameters for remote or external interfaces,
     a line starting with if=alias(Hname), if=remote(Hname), etc. should be

     Lines that	start with neither "net" nor "host" must consist of one	or
     more of the following parameter settings, separated by commas or blanks:

	  indicates that the other parameters on the line apply	to the
	  interface name ifname.

	  advertises a route to	network	nname with mask	mask and the supplied
	  metric (default 1).  This is useful for filling "holes" in CIDR
	  allocations.	This parameter must appear by itself on	a line.	 The
	  network number must specify a	full, 32-bit value, as in
	  instead of 192.0.2.

	  Do not use this feature unless necessary.  It	is dangerous.

	  specifies that netmask of the	network	of which nname/mask1 is	a
	  subnet should	be mask2.  For example ripv1_mask=,27
	  marks as a subnet of instead of

	  specifies a RIPv2 cleartext password that will be included on	all
	  RIPv2	responses sent,	and checked on all RIPv2 responses received.
	  Any blanks, tab characters, commas, or '#', '|', or NULL characters
	  in the password must be escaped with a backslash (\).	 The common
	  escape sequences \n, \r, \t, \b, and \xxx have their usual meanings.
	  The KeyID must be unique but is ignored for cleartext	passwords.  If
	  present, start and stop are timestamps in the	form
	  year/month/day@hour:minute.  They specify when the password is
	  valid.  The valid password with the most future is used on output
	  packets, unless all passwords	have expired, in which case the
	  password that	expired	most recently is used, or unless no passwords
	  are valid yet, in which case no password is output.  Incoming
	  packets can carry any	password that is valid,	will be	valid within
	  24 hours, or that was	valid within 24	hours.	To protect the
	  secrets, the password	settings are valid only	in the /etc/gateways
	  file and only	when that file is readable only	by UID 0.

									Page 6

ROUTED(1M)							    ROUTED(1M)

	  specifies a RIPv2 MD5	password.  Except that a KeyID is required,
	  this keyword is similar to passwd.

	  turns	off aggregation	of subnets in RIPv1 and	RIPv2 responses.

	  turns	off aggregation	of networks into supernets in RIPv2 responses.

	  marks	the interface to not be	advertised in updates sent via other
	  interfaces, and turns	off all	RIP and	router discovery through the

	  disables all RIP processing on the specified interface.  If no
	  interfaces are allowed to process RIP	packets, routed	acts purely as
	  a router discovery daemon.

	  Note that turning off	RIP without explicitly turning on router
	  discovery advertisements with	rdisc_adv or -s	causes routed to act
	  as a client router discovery daemon, not advertising.

	  causes RIPv2 packets to be broadcast instead of multicast.

	  causes RIPv1 received	responses to be	ignored.

	  causes RIPv2 received	responses to be	ignored.

	  turns	off RIPv1 output and causes RIPv2 advertisements to be
	  multicast when possible.

	  is equivalent	to no_ripv1_in and no_ripv1_out.

	  disables the Internet	Router Discovery Protocol.

	  disables the transmission of Router Discovery	Solicitations.

	  specifies that Router	Discovery solicitations	should be sent,	even
	  on point-to-point links, which by default only listen	to Router
	  Discovery messages.

									Page 7

ROUTED(1M)							    ROUTED(1M)

	  disables the transmission of Router Discovery	Advertisements

	  specifies that Router	Discovery Advertisements should	be sent, even
	  on point-to-point links, which by default only listen	to Router
	  Discovery messages

	  specifies that Router	Discovery packets should be broadcast instead
	  of multicast.

	  sets the preference in Router	Discovery Advertisements to the
	  optionally signed integer N.	The default preference is 0.  Default
	  routes with smaller or more negative preferences are preferred by

	  sets the nominal interval with which Router Discovery	Advertisements
	  are transmitted to N seconds and their lifetime to 3*N.

	  has an identical effect to "-F net/mask,metric" with the network and
	  mask coming from the specified interface.

	  is similar to	fake_default.  When RIPv2 routes are multicast,	so
	  that RIPv1 listeners cannot receive them, this feature causes	a
	  RIPv1	default	route to be broadcast to RIPv1 listeners.  Unless
	  modified with	fake_default, the default route	is broadcast with a
	  metric of 14.	 That serves as	a "poor	man's router discovery"

	  causes RIP packets from that router and other	routers	named in other
	  trust_gateway	keywords to be accepted, and packets from other
	  routers to be	ignored.  If networks are specified, then routes to
	  other	networks will be ignored from that router.

	  causes RIP to	allow ICMP Redirect messages when the system is	acting
	  as a router and forwarding packets.  Otherwise, ICMP Redirect
	  messages are overridden.

FILES    [Toc]    [Back]

     /etc/gateways		 for distant gateways
     /etc/config/routed.options	 Site-dependent	options

									Page 8

ROUTED(1M)							    ROUTED(1M)

     gated(1M),	udp(7P), icmp(7P), rtquery(1M)

BUGS    [Toc]    [Back]

     It	does not always	detect unidirectional failures in network interfaces
     (e.g., when the output side fails).

									PPPPaaaaggggeeee 9999
[ Back ]
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