Tribblix: manual page: in.routed.8

IN.ROUTED(8) Maintenance Commands and Procedures IN.ROUTED(8)

NAME

in.routed, routed - network routing daemon

SYNOPSIS

/usr/sbin/in.routed [-AdghmnqsStVz] [-T tracefile [-v]]
[-F net[/mask ][,metric]] [-P params]

DESCRIPTION

The daemon in.routed, often referred to as routed, is invoked at boot
time to manage the network routing tables. It uses Routing
Information Protocol, RIPv1 (RFC 1058), RIPv2 (RFC 2453), and
Internet Router Discovery Protocol (RFC 1256) to maintain the kernel
routing table. The RIPv1 protocol is based on the reference 4.3BSD
daemon.

in.routed is managed by means of the service management facility
(SMF), using the fault management resource identifier (FMRI):

svc:/network/routing/route:default

The daemon listens on a udp socket for the route service (see
services(5)) for Routing Information Protocol packets. It also sends
and receives multicast Router Discovery ICMP messages. If the host is
a router, in.routed periodically supplies copies of its routing
tables to any directly connected hosts and networks. It also
advertises or solicits default routes using Router Discovery ICMP
messages.

When started (or when a network interface is later turned on),
in.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, in.routed
deletes all pre-existing non-static routes in the kernel table.
Static routes in the kernel table are preserved and included in RIP
responses if they have a valid RIP metric (see route(8)).

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, in.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 an
interface (see ifconfig(8)), so setting the metric on an interface is
an effective way to steer traffic.

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(8) are answered with the complete table.

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, in.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, in.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
in.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(8)), then the cable or some other part of the
interface is assumed to be disconnected or broken, and routes are
adjusted appropriately.

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 listening to RIP while using Router Discovery if multi-
homed to ensure all interfaces are used.

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.
See gateways(5).

While using Router Discovery (which happens by default when the
system has a single network interface and a Router Discover
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 the no_rdisc argument described below.

To support "legacy" systems that can handle neither RIPv2 nor Router
Discovery, you can use the pm_rdisc parameter in the /etc/gateways.
See gateways(5).

By default, neither Router Discovery advertisements nor solicitations
are sent over point-to-point links (for example, PPP). The Solaris OE
uses a netmask of all ones (255.255.255.255) on point-to-point links.

in.routed supports the notion of "distant" passive or active
gateways. When the daemon is started, it reads the file
/etc/gateways to find such distant gateways that cannot 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 are advertised via other interfaces. If the distant
gateway resumes sending RIP responses, the associated route is
restored.

Distant active gateways can be useful on media that do not support
broadcasts or multicasts but otherwise act like classic shared media,
such as some ATM networks. One can list all RIP routers reachable on
the HIPPI or 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 other routes
to that destination should not be installed by in.routed. Such
entries are required only when both routers might learn of routes to
the same destination.

OPTIONS

Listed below are available options. Any other argument supplied is
interpreted as the name of a file in which the actions of in.routed
should be logged. It is better to use -T (described below) instead
of appending the name of the trace file to the command. Associated
SMF properties for these options are described, and can be set by
means of a command of the form:

# routeadm -m route:default name=value

-A

Do not ignore RIPv2 authentication if we do not care about RIPv2
authentication. This option is required for conformance with RFC
2453. 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. This option is equivalent to setting the
ignore_auth property value to false.

-d

Do not run in the background. This option is meant for
interactive use and is not usable under the SMF.

-F net[/mask][,metric]

Minimize routes in transmissions via interfaces with addresses
that match net (network number)/mask (netmask), and synthesizes a
default route to this machine with the metric. The intent is to
reduce RIP traffic on slow, point-to-point 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. Use of this option is equivalent to setting
the minimize_routes property.

-g

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. A larger
metric will be used with the latter alternatives, reducing the
spread of the potentially dangerous default route. The -g (or -P)
option 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. Note that because a metric of 1
is used, this feature is dangerous. Its use more often creates
chaos with a routing loop than solves problems. Use of this
option is equivalent to setting the offer_default_route property
to true.

-h

Causes host or point-to-point routes not to 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 LANs that have other gateway machines connected with
point-to-point links such as SLIP. Use of this option is
equivalent to setting the advertise_host_routes property to
false.

-m

Cause 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. Use of this option is
equivalent to setting the advertise_host_routes_primary property
to true.

-n

Do not install routes in kernel. By default, routes are installed
in the kernel. Use of this option is equivalent to setting the
install_routes property to false.

-P params

Equivalent to adding the parameter line params to the
/etc/gateways file. Can also be set by means of the parameters
property.

-q

Opposite of the -s option. This is the default when only one
interface is present. With this explicit option, the daemon is
always in "quiet mode" for RIP and does not supply routing
information to other computers. Use of this option is equivalent
to setting the quiet_mode property to true.

-s

Force in.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 /dev/ip
ndd variable ip_forwarding is set to 1. Use of this option is
equivalent to setting the supply_routes property to true.

-S

If in.routed is not acting as an internetwork router, instead of
entering the whole routing table in the kernel, it enters only a
default route for each internetwork router. This reduces the
memory requirements without losing any routing reliability. This
option is provided for compatibility with the previous,
RIPv1-only in.routed. Use of this option is generally
discouraged. Use of this option is equivalent to setting the
default_routes_only property to true.

-t

Runs in the foreground (as with -d) and logs the contents of the
packets received (as with -zz). This is for compatibility with
prior versions of Solaris and has no SMF equivalent.

-T tracefile

Increases the debugging level to at least 1 and causes debugging
information to be appended to the trace file. Because of security
concerns, do not to run in.routed routinely with tracing directed
to a file. Use of this option is equivalent to setting the
log_file property to trace file path.

-v

Enables debug. Similar to -z, except, where -z increments
trace_level, -v sets trace_level to 1. Also, -v requires the -T
option. Use of this option is equivalent to setting the debug
property to true.

-V

Displays the version of the daemon.

-z

Increase the debugging level, which causes more information to be
logged on the tracefile specified with -T or stdout. The
debugging level can be increased or decreased with the SIGUSR1 or
SIGUSR2 signals or with the rtquery(8) command.

FILES

/etc/defaultrouter
If this file is present and contains the
address of a default router, the system startup
script does not run in.routed. See
defaultrouter(5).

/etc/gateways
List of distant gateways and general
configuration options for in.routed. See
gateways(5).

NOTES

In keeping with its intended design, this daemon deviates from RFC
2453 in two notable ways:

o By default, in.routed does not discard authenticated RIPv2
messages when RIP authentication is not configured. There
is little to gain from dropping authenticated packets when
RIPv1 listeners will gladly process them. Using the -A
option causes in.routed to conform to the RFC in this
case.

o Unauthenticated RIP requests are never discarded, even
when RIP authentication is configured. Forwarding tables
are not secret and can be inferred through other means
such as test traffic. RIP is also the most common router-
discovery protocol, and hosts need to send queries that
will be answered.

in.routed does not always detect unidirectional failures in network
interfaces, for example, when the output side fails.

March 30, 2022 IN.ROUTED(8)

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

FILES

SEE ALSO

NOTES