routed - Manages network routing tables
/usr/sbin/routed [-dgt] [-q|-s] [logfile]
-d 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
-g 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.
-q 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.
-s 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.
-t 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 pro-
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
Use the routed daemon to manage the RIP only. Use gated to manage RIP plus
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 routing 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 infor-
mation, (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
+ 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 internal
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 invali-
dated 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.
In addition to managing routes to directly connected hosts and networks,
routed maintains information about distant and external gateways. At
startup, routed reads the /etc/gateways file to learn about these gateways.
The /etc/gateways file contains information about routes through distant
and external gateways to hosts and networks that can be advertised through
RIP. These routes are either static routes to specific destinations, or
default routes that apply when a static route to a destination is unspeci-
Gateways that supply RIP routing information are marked active in the
/etc/gateways file. The routed daemons distributes RIP routing information
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
Gateways that do not exchange RIP routing information are marked passive 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 routing
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
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 messages sent and
received that are related to changed routes.
The following signals have the specified effect when sent to the routed
process using the kill(1) command:
Displays internal routing tables.
SIGHUP, SIGTERM, or SIGQUIT
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.
1. The gated and routed daemons should not both be run on the same host,
as this may produce unpredictable results.
2. Routes through external gateways must be to networks only.
Specifies the command path
Routes through distant and external gateways
Contains the network name database