| ROUTED(8) | System Manager's Manual | ROUTED(8) | 
routed, rdisc —
| routed | [ -sqdghmAtv] [-Ttracefile] [-Fnet[/mask[,metric]]] [-Pparms] | 
routed is a daemon 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(4) socket for the
    route(8) 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,
    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),
    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
    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,
    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"). The advertised metric for a route reflects the
    metrics associated with interfaces (see
    ifconfig(8)) through which
    it is received and sent, so setting the metric on an interface is an
    effective way to steer traffic. See also
    adj_inmetric and
    adj_outmetric parameters below.
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, 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 ensure 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(1)), 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.
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 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.
The following options are available:
-srouted 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 sysctl
      net.inet.ip.forwarding=1.-q-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.-d-g-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 a
      routing loop than to solve problems.-h-m-m option
      overrides the -q option to the limited extent of
      advertising the host route.-A-t-T or standard
      out. The debugging level can be increased or decreased with the
      SIGUSR1 or SIGUSR2 signals or with the
      rtquery(8) command.-T
    tracefilerouted
      routinely with tracing directed to a file.-v-F
    net[/mask][,metric]-g.-P
    parmsAny other argument supplied is interpreted as the name of a file
    in which the actions of routed 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 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
    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
  | extern>host Hname
  gateway Gname
  metric value
  <passive |
  active |
  extern>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(3)). (If it is a name, then
    it must either be defined in /etc/networks or
    /etc/hosts, or
    named(8), 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 .
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
    -t, such lines create pseudo-interfaces. To set
    parameters for remote or external interfaces, a line starting with
    if=alias(Hname),
    if=remote(Hname), etc. should be used.
if=ifnamesubnet=nname[/mask][,metric]Do not use this feature unless necessary. It is dangerous.
ripv1_mask=nname/mask1,mask2nname/mask1 is a subnet should be
      mask2. For example
      ripv1_mask=192.0.2.16/28,27
      marks 192.0.2.16/28 as a subnet of 192.0.2.0/27 instead of 192.0.2.0/24.
      It is better to turn on RIPv2 instead of using this facility, for example
      with ripv2_out.passwd=XXX[|KeyID[start|stop]]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 the next 24 hours, or that was valid within the
      preceding 24 hours. To protect the secrets, the passwd settings are valid
      only in the /etc/gateways file and only when that file
      is readable only by UID 0.md5_passwd=XXX|KeyID[start|stop]KeyID is required, this keyword is similar to
      passwd.no_agno_super_agpassiveno_riprouted 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.
no_rip_mcastno_ripv1_inno_ripv2_inripv2_outripv2no_ripv1_in and
      no_ripv1_out. This enables RIPv2.no_rdiscno_solicitsend_solicitno_rdisc_advrdisc_advbcast_rdiscrdisc_pref=Nrdisc_interval=Nfake_default=metric-F
      net[/mask][=metric] with the network and mask coming
      from the specified interface.pm_rdiscfake_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" protocol.adj_inmetric=deltaadj_outmetric=deltaadj_inmetric delta of
      the receiving interface, the metric set for the interface by which it is
      transmitted with
      ifconfig(8), and the
      adj_outmetric delta of the
      transmitting interface.trust_gateway=rname[|net1/mask1|net2/mask2|...]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.redirect_okInternet Transport Protocols, XSIS 028112, Xerox System Integration Standard.
routed command appeared in
  4.2BSD.
| May 17, 2004 | NetBSD 9.4 |