System Administration Commands                      in.routed(1M)

NAME
     in.routed, routed - network routing daemon

SYNOPSIS
     /usr/sbin/in.routed [-AdghmnqsStvVz] [-T tracefile] [-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.

     The daemon listens on a udp 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, in.routed periodically
     supplies copies of its routing tables to any  directly  con-
     nected  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(1M)).

     If more than one interface  is  present  (not  counting  the
     loopback interface), it is assumed that the host should for-
     ward packets among the connected networks.  After  transmit-
     ting  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(1M)), 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(1M)   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  adver-
     tise a better metric than at least one of the existing gate-
     ways.

     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  infnite
     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 alter-
     nate 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 con-
     nected 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 multi-
     casting.

     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
     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  gate-
     ways(4).

     While using Router Discovery (which happens by default  when
     the  system has a single network interface and a Router Dis-
     cover 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  inter-
     face,  this default route will be via only one of the inter-
     faces. 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(4).

     By default, neither Router Discovery advertisements nor sol-
     icitations  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  destina-
     tion  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  sup-
     plied  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.

     -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.



     -d

         Do not run in the background. This option is  meant  for
         interactive use.



     -F net[/mask][,metric]

         Minimize routes in  transmissions  via  interfaces  with
         addresses  that  match  net  (network number)/mask (net-
         mask), 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.



     -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 rout-
         ing loop than solves problems.



     -h

         Causes host or point-to-point routes not  to  be  adver-
         tised,  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.



     -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 rout-
         ing information, because there is more than  one  inter-
         face.  The -m option overrides the -q option to the lim-
         ited extent of advertising the host route.



     -n

         Do not install routes in kernel. By default, routes  are
         installed in the kernel.



     -P params

         Equivalent to adding the parameter line  params  to  the
         /etc/gateways file.



     -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.



     -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.



     -S

         If in.routed is not acting as  an  internetwork  router,
         instead  of entering the whole routing table in the ker-
         nel, it enters only a default route for  each  internet-
         work   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.


     -t

         Runs in the foreground (as with -d) and  logs  the  con-
         tents of the packets received (as with -zz). This is for
         compatibility with prior versions of Solaris.



     -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.



     -v

         Enables debug. Same as -z.



     -V

         Displays the version of the daemon.



     -z

         Increase the debugging level, which causes more informa-
         tion  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(1M) 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(4).



     /etc/gateways           List of distant gateways and general
                             configuration options for in.routed.
                             See gateways(4).


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWroute                   |
    |_____________________________|_____________________________|


SEE ALSO
     route(1M),  rtquery(1M),  ioctl(2),  inet(3SOCKET),  defaul-
     trouter(4),  gateways(4), attributes(5), icmp(7P), inet(7P),
     udp(7P)

     Internet Transport  Protocols,  XSIS  028112,  Xerox  System
     Integration Standard

     Routing  Information  Protocol,  v2  (RFC  2453,  STD  0056,
     November 1998)

     RIP-v2 MD5 Authentication (RFC 2082, January 1997)

     Routing Information Protocol, v1 (RFC 1058, June 1988)

     ICMP Router Discovery Messages (RFC 1256, September 1991)

NOTES
     This daemon purposefully deviates from RFC 2453 in two  not-
     able ways:

       o  By default, in.routed does  not  discard  authenticated
          RIPv2  messages  when RIP authentication is not config-
          ured. There is little to gain from  dropping  authenti-
          cated  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.