routed(8)routed(8)NAMErouted - Manages network routing tables
SYNOPSIS
/usr/sbin/routed [-dgt] [-q|-s] [logfile]
OPTIONS
Enables additional debugging information, such as bad packets received,
to be logged. The routed daemon remains under control of the host that
started it; therefore, an interrupt from the controlling host stops the
routed process. Causes the routing daemon to run on a gateway host.
This option is used on internetwork routers to offer a route to the
default destination. Inhibits the routed daemon from supplying Routing
Information Protocol (RIP) data. The -q option conflicts with the -s
option. Do not use the -q and -s options together. Causes routed to
supply RIP information even if it is not functioning as an Internet
router. The -s option conflicts with the -q option. Do not use the -s
and -q options together. Causes all packets sent or received to be
written to standard output. The routed daemon remains under control of
the host that started it; therefore, an interrupt from the controlling
host stops the routed process.
OPERANDS
The optional logfile operand specifies a log file where the routed dae‐
mon writes information about its actions. This log contains informa‐
tion about any changes to the routing tables and a history of recent
route change messages sent and received that are related to changed
routes.
DESCRIPTION
Use the routed daemon to manage the RIP only. Use gated to manage RIP
plus other protocols.
When routed starts, it finds any interfaces to directly connected hosts
and networks that are configured into the system and marked as up. If
multiple interfaces are present, routed assumes that the local host
forwards packets between networks. The routed daemon transmits an RIP
request packet on each interface (using a broadcast packet if the
interface supports it) and then enters a loop, listening for RIP rout‐
ing requests and response packets from other hosts. In addition, if
routed is to supply RIP information to other hosts, it periodically
sends RIP update packets (containing copies of its routing tables) to
any directly connected hosts and networks.
When routed receives a RIP request packet and can supply RIP routing
information, (the -s option is set), it generates a reply (response
packet) based on the information maintained in the kernel routing
tables. The response packet contains a list of known routes, each
marked with a hop count metric (the number of host-to-host connections
in the route). The metric for each route is relative to the sending
host. A metric of 16 or greater is considered to be infinite, or beyond
reach.
Updating Routing Tables
If RIP processing is enabled, routed uses information contained in the
RIP response and update packets from other hosts to update its routing
tables. However, routed uses the information in the RIP routing packet
to update the tables only if at least one of the following conditions
exists: No routing table entry exists for the destination network or
host, and the metric associated with the route is finite (that is, the
metric is less than 16). The source host of the packet is the router
in the existing routing table entry. The routing table entry is old
and the new information is about a route that is at least as efficient
as the existing route. The new route is shorter than the one that is
currently stored in the routing tables. (Note that routed determines
relative route length by comparing the new metric with the one stored
in the routing table.)
When routed updates its internal routing tables, it generates an RIP
update packet to all directly connected hosts and networks. Before
updating the kernel routing tables, routed pauses for a brief period to
allow any unstable conditions to stabilize.
Besides processing incoming RIP packets, routed also checks the inter‐
nal routing table entries periodically. The metric for any entry that
has not been updated for 3 minutes is set to infinity and marked for
deletion. The deletion is delayed for 60 seconds so that information
about the invalidated route can be distributed throughout the network.
A host that acts as an RIP router supplies its routing tables to all
directly connected hosts and networks every 30 seconds.
Using Gateways
In addition to managing routes to directly connected hosts and net‐
works, routed maintains information about distant and external gate‐
ways. At startup, routed reads the /etc/gateways file to learn about
these gateways.
The /etc/gateways file contains information about routes through dis‐
tant and external gateways to hosts and networks that can be advertised
through RIP. These routes are either static routes to specific destina‐
tions, or default routes that apply when a static route to a destina‐
tion is unspecified.
Gateways that supply RIP routing information are marked active in the
/etc/gateways file. The routed daemons distributes RIP routing informa‐
tion to active gateways; if no RIP routing information is received from
the gateway for a period of time, routed deletes the associated route
from the routing tables.
Gateways that do not exchange RIP routing information are marked pas‐
sive in the /etc/gateways file. The routed daemon maintains information
about passive gateways indefinitely, and includes information about
them in any RIP routing information transmitted.
Gateways are identified as external to inform routed that another rout‐
ing process installs the route.
Information about external gateways is not maintained in the routing
tables. Note that routes through external gateways must be to networks
only.
If a logfile is specified, routed writes information about its actions
to the specified log file. The log contains information about any
changes to the routing tables and a history of recent route change mes‐
sages sent and received that are related to changed routes.
Signals
The following signals have the specified effect when sent to the routed
process using the kill(1) command: Displays internal routing tables.
Broadcasts RIP packets with hop counts set to infinity. Essentially,
these signals disable the local host as a router. On a second SIGHUP,
SIGTERM, or SIGQUIT, routed terminates.
RESTRICTIONS
The gated and routed daemons should not both be run on the same host,
as this may produce unpredictable results. Routes through external
gateways must be to networks only.
FILES
Specifies the command path Routes through distant and external gateways
Contains the network name database
SEE ALSO
Commands: route(8)
Daemons: gated(8)routed(8)
