gateways(4)gateways(4)NAMEgateways - Specifies Internet routing information to the routed daemon
SYNOPSIS
/etc/gateways
DESCRIPTION
The /etc/gateways file identifies gateways for the routed daemon. Ordi‐
narily, the routed daemon queries the network and builds routing
tables. The routed daemon builds the tables from routing information
transmitted by other hosts directly connected to the network. However,
there may be gateways that this command cannot identify through its
queries. These unidentified gateways are known as distant gateways.
Such gateways should be identified in the /etc/gateways file, which the
routed daemon reads when it starts.
The general format of an file entry in the /etc/gateways file is: Des‐
tination Name1 gateway Name2 metric Value Type
The following is a brief description of each element in an /etc/gate‐
ways file entry: A keyword that indicates whether the route is to a
network or to a specific host. The two possible keywords are net and
host. The name associated with Destination. Name1 can be either a
symbolic name (as used in the /etc/hosts or /etc/networks file) or an
Internet address specified in dotted-decimal format. An indicator that
the following string identifies the gateway host. The name or address
of the gateway host to which messages should be forwarded. An indica‐
tor that the next string represents the hop count to the destination
host or network. The hop count, or number of gateways, from the local
network to the destination network. A keyword that indicates whether
the gateway should be treated as active, passive, or external. The
three possible keywords are as follows: An active gateway is treated
like a network interface. That is, it is expected to exchange RIP
(Routing Information Protocol) routing information. Information about
it is maintained in the internal routing tables as long as it is active
and is included in any routing information that is transmitted through
RIP. If it does not respond for a period of time, the route associated
with it is deleted from the internal routing tables. A passive gateway
is not expected to exchange RIP routing information. Information about
it is maintained in the routing tables indefinitely and is included in
any routing information that is transmitted through RIP. An external
gateway is identified to inform the routed daemon that another routing
process will install such a route and that alternative routes to that
destination should not be installed. Information about external gate‐
ways is not maintained in the internal routing tables and is not trans‐
mitted through RIP.
Note that these routes must be to networks.
EXAMPLES
To specify a route to a network through a gateway host with an entry in
the gateways file, enter: net net2 gateway host4 metric 4 passive
This example specifies a route to a network, net2, through the
gateway host4. The hop count metric to net2 is 4, and the gate‐
way is treated as passive. To specify a route to a host through
a gateway host with an entry in the gateways file, enter: host
host2 gateway host4 metric 4 passive
This example specifies a route to a host, host2, through the
gateway host4. The hop count metric to host2 is 4, and the gate‐
way is treated as passive. To specify a route to a host through
an active Internet gateway with an entry in the gateways file,
enter: host host10 gateway 192.100.11.5 metric 9 active
This example specifies a route to a specific host, host10,
through the gateway 192.100.11.5. The hop count metric to host10
is 9 and the gateway is treated as active. To specify a route
to a host through a passive Internet gateway with an entry in
the gateways file, enter: host host10 gateway 192.100.11.5 met‐
ric 9 passive
This example specifies a route to a specific host, host10,
through the gateway 192.100.11.5. The hop metric count to
host10 is 9 and the gateway is treated as passive. To specify a
route to a network through an external gateway, enter a line in
the following format: net net5 gateway host7 metric 11 external
This example specifies a route to a network, net5, through the
gateway host7. The hop count metric to net5 is 11 and the gate‐
way is treated as external (that is, it is not advertised
through RIP, but is advertised through an unspecified routing
protocol).
SEE ALSO
Daemons: gated(8), routed(8)gateways(4)