GATED(1M)GATED(1M)NAMEgated - gateway routing daemon
SYNOPSIS
/usr/etc/gated [ -t[ierpuRH] ] [ logfile ]
DESCRIPTION
Gated is a routing daemon that handles multiple routing protocols and
replaces routed(1M), egpup(1M), and any routing daemon that speaks the
HELLO routing protocol. Gated currently handles the RIP, EGP, and HELLO
routing protocols. Gated can be configured to perform all routing
protocols or any combination of the three. The configuration for gated
is stored in the file /usr/etc/gated.conf.
COMMAND LINE TRACING OPTIONS
Gated can be invoked with a number of tracing flags and/or a log file.
Tracing flags may also be specified in the configuration file with the
``traceflags'' clause. Gated forks and detaches itself from the
controlling terminal unless tracing flags are specified without
specifying a log file, in which case all tracing output is sent to the
controlling terminal. The valid tracing flags are as follows:
-t If used alone, log all error messages, route changes and EGP packets
sent and received. Using this flag alone turns on the i, e, r, and
p trace flags automatically. When used with another flag, the -t
has no effect and only the accompanying flags are recognized. Note
that when using other flags, -t must be used with them.
i Log all internal errors and interior routing errors.
e Log all external errors due to EGP, exterior routing errors, and EGP
state changes.
r Log all routing changes.
p Trace all EGP packets sent and received.
u When used with p, R, H or N, display the entire contents of routing
packets sent and received.
R Trace all RIP packets sent or received.
H Trace all HELLO packets sent or received.
N Trace all SNMP transactions.
Gated always logs fatal errors. If no log file is specified and no
tracing flags are set, all messages are sent to /dev/null.
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GATED(1M)GATED(1M)SIGNAL PROCESSING
Gated catches a number of signals and performs specific actions.
Currently gated does special processing with the SIGHUP, SIGINT and
SIGUSR1 signals.
When a SIGHUP is sent to gated and gated is invoked with trace flags and
a log file, tracing is toggled off and the log file is closed. At this
point the log file may be moved or removed. The next SIGHUP to gated
will toggle the tracing on. Gated reads the configuration file and sets
the tracing flags to those specified with the ``traceflags'' clause. If
no ``traceflags'' clause is specified tracing is resumed using the trace
flags specified on the command line. The log file specified in the
command line is created if necessary and the trace output is sent to that
file. The trace output is appended to an already existing log file.
This is useful for having rotating log files like those of the syslog(1M)
daemon.
Sending gated a SIGINT will cause a memory dump to be scheduled within
the next sixty seconds. The memory dump will be written to the file
/usr/tmp/gated_dump. Gated will finish processing pending routing updates
before performing the memory dump. The memory dump contains a snapshot
of the current gated status, including the interface configurations, EGP
neighbor status and the routing tables. If the file /usr/tmp/gated_dump
already exists, the memory dump will be appended to the existing file.
On receipt of a SIGUSR1, gated will reread selected information from the
configuration file. This information currently includes the
``announcetoAS'', ``noannouncetoAS'' and ``validAS''. If no errors are
detected the new configuration information is put into effect, if errors
are detected, the configuration information is not changed. Gated will
also check the interface status on receipt of a SIGUSR1.
CONFIGURATION FILE OPTIONS FOR CONTROLLING TRACING OUTPUT
traceflags traceflag [traceflag] [traceflag] ...
The clause tells the gated process what level of tracing output is
desired. This option is read during gated initialization and whenever
gated receives a SIGHUP. This option is overridden at initialization
time if tracing flags are specified on the command line. The valid
tracing flags are as follows:
internal Log all internal errors and interior routing errors.
external Log all external errors due to EGP, exterior routing errors,
and EGP state changes.
route Log all routing changes.
egp Trace all EGP packets sent and received.
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update When used with egp, rip, hello or snmp, display the contents
of all routing packets sent and received.
rip Trace all RIP packets sent and received.
hello Trace all HELLO packets sent and received.
icmp Trace all ICMP redirect packets received.
snmp Trace all SNMP transactions.
stamp Print a timestamp to the log file every 10 minutes.
general A combination of ``internal'', ``external'', ``route'' and
``egp''.
all Enable all of the above tracing flags.
If more than one ``traceflags'' clause is used, the tracing flags
accumulate.
DEFAULT CONFIGURATION
Gated normally reads configuration information from /usr/etc/gated.conf.
If this file does not exist, gated assumes a default configuration file
of:
RIP yes
HELLO no
EGP no
In addition, if the configuration file does not exist, there is only one
network interface, and a default route is installed in the kernel, gated
will exit assuming that a simple default route is adequate.
CONFIGURATION FILE OPTIONS FOR HANDLING ROUTING PROTOCOLS
In this section, the numerous configuration options are explained. Each
time the gated process is started, it reads the file /usr/etc/gated.conf
to obtain its instructions on how routing will be managed with respect to
each protocol. The configuration options are as follows:
RIP {yes | no | supplier | pointopoint | quiet | gateway #}
This tells the gated process how to perform the RIP routing protocol.
Only one of the above RIP arguments is allowed after the keyword ``RIP''.
If more than one is specified, only the first one is recognized. A list
of the arguments to the RIP clause follows:
yes Perform the RIP protocol. Process all incoming RIP packets
and supply RIP information every thirty seconds only if there
are two or more network interfaces.
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no Do not perform the RIP protocol. Do not perform RIP.
supplier Perform the RIP protocol. Process all incoming RIP packets
and force the supplying of RIP information every thirty
seconds no matter how many network interfaces are present.
pointopoint Perform the RIP protocol. Process all incoming RIP packets
and force the supplying of RIP information every thirty
seconds no matter how many network interfaces are present.
When this argument is specified, RIP information will not be
sent out in a broadcast packet. The RIP information will be
sent directly to the gateways listed in the
``sourceripgateways'' option described below.
quiet Process all incoming RIP packets, but do not supply any RIP
information no matter how many network interfaces are
present.
gateway # Process all incoming RIP packets, supply RIP information
every thirty seconds, and announce the default route
(0.0.0.0) with a metric of #. The metric should be specified
in a value that represents a RIP hopcount. With this option
set, all other default routes coming from other RIP gateways
will be ignored. The default route is only announced when
actively peering with at least one EGP neighbor and therefore
should only be used when EGP is used.
If no ``RIP'' clause is specified, RIP will not be performed.
HELLO {yes | no | supplier | pointopoint | quiet| gateway #}
This tells gated how to perform the HELLO routing protocol. The
arguments parallel the RIP arguments, but do have some minor differences.
Only one of the above HELLO arguments is allowed after the keyword
``HELLO''. If more than one is specified, only the first one is
recognized. A list of the arguments to the HELLO clause follows:
yes Perform the HELLO protocol. Process all incoming HELLO
packets and supply HELLO information every fifteen seconds
only if there are two or more network interfaces.
no Do not perform the HELLO protocol. Do not perform HELLO.
supplier Perform the HELLO protocol. Process all incoming HELLO
packets and force the supplying of HELLO information every
fifteen seconds no matter how many network interfaces are
present.
pointopoint Perform the HELLO protocol. Process all incoming HELLO
packets and force the supplying of HELLO information every
fifteen seconds no matter how many network interfaces are
present. When this argument is specified, HELLO
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information will not be sent out in a broadcast packet.
The HELLO information will be sent directly to the gateways
listed in the ``sourcehellogateways'' option described
below.
quiet Process all incoming HELLO packets, but do not supply any
HELLO information despite the number of network interfaces
present.
gateway # Process all incoming HELLO packets, supply HELLO
information every fifteen seconds, and announce the default
route (0.0.0.0) with a time delay of #. The time delay
should be specified in milliseconds. The default route is
only announced when actively peering with at least one of
EGP neighbor, therefore should only be used when running
EGP.
If no ``HELLO'' clause is specified, HELLO will not be performed.
EGP {yes | no}
This clause allows the processing of EGP by gated to be turned on or off.
no Do not perform any EGP processing.
yes Perform all EGP operations.
Please note that by default, EGP processing will take place. Therefore,
if no ``EGP'' clause is specified, all EGP operations will take place.
autonomoussystem #
If performing the EGP protocol, this clause must be used to specify the
autonomous system number (#). If not specified, gated will exit and give
a fatal error message.
egpmaxacquire #
If performing the EGP protocol, this clause specifies the number of EGP
peers with whom gated will be performing EGP. This number must be
greater than zero and less than or equal to the number of EGP neighbors
specified or gated will exit. If this clause is omitted, all EGP
neighbors will be acquired.
egpneighbor gateway
metricin metric
egpmetricout egpmetric
ASin asin
ASout asout
AS as
nogendefault
acceptdefault
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defaultout egpmetric
validate
intf interface
sourcenet net
gateway gateway
If performing the EGP protocol, this clause specifies with whom gated
will be performing EGP. ``Gateway'' can be either a symbolic name in
/etc/hosts or an IP hostname in Internet dot (a.b.c.d) notation. Dot
notation is recommended to avoid confusion. Each EGP neighbor will be
acquired in the order listed in the configuration file.
The ``metricin'' option is used to specify the internal time delay to be
used as a metric for all of the routes learned from this neighbor. It
should be specified as a time delay from zero to 30000. If this option
and the validate option are not used, the internal metric used is the EGP
distance multiplied by 100.
The ``egpmetricout'' option is used to specify the EGP distance used for
all nets advertised to this neighbor. It should be specified as an EGP
distance in the range of 0 to 255. If this option is not specified, the
internal time delay for each route will be converted to an EGP distance
by division by 100 with distances greater than 255 being set to 255.
The ``ASin'' option is used to verify the autonomous system number of
this neighbor. If the autonomous system number specified in neighbor
acquisition packets does not verify an error message is generated
refusing the connection. If this option is not specified, no
verification of autonomous system numbers is done.
The ``ASout'' option is used to specify the autonomous system number in
EGP packets sent to this neighbor. If not specified, the autonomous
system specified in the ``autonomoussystem'' clause is used. This clause
should not normally be used, it is reserved for a special situation
interfacing between the ARPAnet and NSFnet.
The ``AS'' option is used to specify that autonomous system number that
will be assigned to routes learned from this neighbor. If not specified,
the autonomous system used in the EGP packets received from this neighbor
will be used. This clause should not normally be used, it is reserved
for a special situation interfacing between the ARPAnet and NSFnet.
The ``nogendefault'' option is used to specify this neighbor should not
be considered for the internal generation of default when ``RIP gateway''
or ``HELLO gateway'' is used. If not specified, the internal default
will be generated when actively peering with this neighbor.
The ``acceptdefault'' option is used to specify that the default route
(net 0.0.0.0) should be considered valid when received from this
neighbor. If this option is not specified, the reception of the default
route will cause a warning message to be printed and the route to be
ignored.
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The ``defaultout'' option is used to specify that the internally
generated default may be passed to this EGP neighbor at the specified
distance. The distance should be specified as an EGP distance from 0 to
255. A default route learned from another gateway will not be propagated
to an EGP neighbor. Normally, no default route will be passed via EGP.
The ``acceptdefault'' option should not be specified when the
``defaultout'' option is used. The egpmetric specified in the
``egpmetricout'' option does not apply, the default route will always use
the metric specified by the ``defaultout'' option.
The ``validate'' option is used to specify that all networks received
from this EGP neighbor must be specified in ``validAS'' clause that also
specifies the autonomous system of this neighbor. Networks not having a
``validAS'' clause will be ignored after a warning message is printed.
The ``intf'' option is used to specify the interface used to send EGP
packets to this neighbor. This option is only required when there is no
common net/subnet with this egpneighbor. This option currently is only
present for testing purposes and does not imply correct operation when
peering with an egpneighbor that does not share a common net/subnet.
The ``sourcenet'' option is used to specify the source network to be
specified in EGP poll packets sent to this neighbor. If this option is
not specified, the network (not subnet) of the interface used to
communicate with this neighbor is used. This option is currently only
present for testing purposes and does not imply correct operation when
used.
The ``gateway'' option is used to specify the gateway to be used when
installing routes learned from an EGP neighbor on a different network.
Normally these routes would be ignored. This option is currently only
present for testing purposes and correct operation can not be assured
when it is used.
CONFIGURATION FILE OPTIONS FOR HANDLING ROUTING INFORMATION
The following configuration file options tell gated how to deal with both
incoming and outgoing routing information.
trustedripgateways gateway [gateway] [gateway] .....
trustedhellogateways gateway [gateway] [gateway] .....
When these clauses are specified, gated will only listen to RIP or HELLO
information, respectively from these RIP or HELLO gateways. ``gateway''
can be either a symbolic name from /etc/hosts or an IP host address in
dot notation (a.b.c.d). Again, dot notation is recommended to eliminate
confusion. Please note that the propagation of routing information is
not restricted by this clause.
sourceripgateways gateway [gateway] [gateway] .....
sourcehellogateways gateway [gateway] [gateway] .....
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Gated will send RIP or HELLO information directly to the gateways
specified. If ``pointopoint'' is specified in the ``RIP'' or ``HELLO''
clauses mentioned above, gated will only send RIP or HELLO information to
the specified gateways. Gated will NOT send out any information using
the broadcast address. If ``pointopoint'' is not specified in those
clauses and gated is supplying of RIP or HELLO information, gated will
send information to the specified gateways as well as broadcasting it
using a broadcast address.
noripoutinterface intfaddr [intfaddr] [intfaddr] .....
nohellooutinterface intfaddr [intfaddr] [intfaddr] .....
noripfrominterface intfaddr [intfaddr] [intfaddr] .....
nohellofrominterface intfaddr [intfaddr] [intfaddr] .....
The above clauses turn protocols on and off on a per interface basis.
``no{rip|hello}frominterface'' means that no RIP or HELLO information
will be accepted coming into the listed interfaces from another gateway.
``no{rip|hello}outinterface'' means that no RIP or HELLO knowledge will
be sent out of the listed interfaces. ``intfaddr'' should be in dot
notation (a.b.c.d).
passiveinterfaces intfaddr [intfaddr] [intfaddr] .....
In order to dynamically determine if an interface is properly
functioning, gated will time out an interface when no RIP, HELLO or EGP
packets are being received on that particular interface. PSN interfaces
send a RIP or HELLO packet to themselves to determine if the interface is
properly functioning as the delay between EGP packets may be longer than
the interface timeout. Interfaces that have timed out automatically have
their routes re-installed when routing information is again received over
the interface. The above clause stops gated from timing out the listed
interfaces. The interfaces listed will always be considered up and
working. If gated is not a RIP or HELLO supplier, all interfaces will
not be aged and the ``passiveinterfaces'' automatically applies to all
interfaces.
interfacemetric intfaddr metric#
This feature allows the specification of an interface metric for the
listed interface. On systems that support interface metrics, this clause
will override the kernel's metric. On systems that do not have support
for an interface metric, this feature allows the specification of one.
The interface metric is added to the true metric of each route that comes
in via routing information from the listed interface. The interface
metric is also added to the true metric of any information sent out via
the listed interface. The metric of directly attached interfaces is also
set to the interface metric, routing information broadcast about directly
attached nets will be based on the interface metric specified. This
clause is required for each interface on which an interface metric is
desired.
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reconstmetric intfaddr metric#
This is a first attempt to throw hooks for fallback routing into gated.
If the above clause is used, the metrics of the routes contained in any
RIP information coming into the listed interface will be set to the
specified ``metric#''. Metric reconstitution should not be used lightly,
since it could be a major contributor in the formation of routing loops.
USE THIS WITH EXTREME CAUTION. Any route that has a metric of infinity
will not be reconstituted and left as infinity.
fixedmetric intfaddr proto {rip|hello} metric#
This is another attempt to throw hooks for fallback routing into gated.
If the above clause is used, all routing information sent out the
specified interface will have a metric of ``metric#''. For RIP, specify
the metric as a RIP hopcount from 0 to infinity. For HELLO, specify the
metric as a HELLO delay in milliseconds from 0 to infinity. Any route
that has a metric of infinity will be left as infinity. Fixed metrics
should also be USED WITH EXTREME CAUTION!
donotlisten net intf addr [addr] ... proto {rip|hello}
donotlistenhost host intf addr [addr] ... proto {rip|hello}
This clause reads as follows: keyword ``donotlisten'' followed by a
network number, which should be in dot notation followed by keyword
``intf''. Then a list of interfaces in dot notation precede the keyword
``proto'', followed by ``rip'' or ``hello''.
This means that any information regarding ``net'' coming in via the
specified protocols AND from the specified interfaces will be ignored.
The keyword ``all'' may be used after the keyword ``intf'' to specify all
interfaces on the machine. For example:
donotlisten 10.0.0.0 intf 128.84.253.200 proto rip
means that any RIP information about net 10.0.0.0 coming in via interface
128.84.253.200 will be ignored. One clause is required for each net on
which this restriction is desired.
donotlisten 26.0.0.0 intf all proto rip hello
means that any RIP and HELLO information about net 26.0.0.0 coming in via
any interface will be ignored.
``donotlistenhost'' can be described the same way as above except that a
host address is provided instead of a network address. Restrictions of
the nature described above are applied to the specified host route
learned of by the specified routing protocol.
listen net gateway addr [addr] ... proto {rip|hello}
listenhost host gateway addr [addr] ... proto {rip|hello}
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This clause reads as follows: keyword ``listen'' followed by a network
number which should be in dot notation followed by keyword ``gateway''.
Then a list of gateways in dot notation should precede the keyword
``proto'', followed by ``rip'' or ``hello''.
This means to only listen to information about network ``net'' by the
specified protocol(s) only from the listed ``gateways''. For example:
listen 128.84.0.0 gateway 128.84.253.3 proto hello
means that any HELLO information about net 128.84 coming in via gateway
128.84.253.3 will be accepted. Any other information about 128.84 from
any other gateway will be rejected. One clause is necessary for each net
to be restricted.
listenhost 26.0.0.15 gateway 128.84.253.3 proto rip
means that any information about host 26.0.0.15 must come via RIP and
from gateway 128.84.253.3. All other information regarding this host
will be ignored.
announce net intf addr [addr] ... proto type [egpmetric #]
announcehost host intf addr ... proto type [egpmetric #]
noannounce net intf addr [addr] ... proto type [egpmetric #]
noannouncehost host intf addr ... proto type [egpmetric #]
These clauses allow restriction of the networks and hosts announced and
by which protocol. The ``announce{host}'' and ``noannounce{host}''
clauses may not be used together on the same interface. With the
``announce{host}'' clause, gated will only announce the nets or hosts
that have an associated ``announce{host}'' clause with the appropriate
protocol. With the ``noannounce{host}'' clause, gated will announce
everything, EXCEPT those nets or hosts that have an associated
``noannounce{host}'' clause. This allows a choice of announcing only
what is on the announce list or everything except those nets on the
noannounce list on a per interface basis.
The arguments are the same as in the ``donotlisten'' clause except
``egp'' may be specified in the ``proto'' field. ``type'' can either be
``rip'', ``hello'', ``egp'', or any combination of the three. When
``egp'' is specified in the ``proto'' field, an egp metric must be
specified. This is the metric at which gated will announce the listed
net via EGP.
Please note that these are not static route entries. These restrictions
will only apply if the net or host is learned via one of the routing
protocols. If a restricted network suddenly becomes unreachable and goes
away, announcement of this net will stop until it is learned again.
Currently, only one ``announce{host}'' or ``noannounce{host}'' may be
specified per network or host. It is not possible to announce a network
or host via HELLO out one interface and via RIP out another.
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Some examples:
announce 128.84 intf all proto rip hello egp egpmetric 0
announce 10.0.0.0 intf all proto rip
announce 0.0.0.0 intf 128.84.253.200 proto rip
announce 35.0.0.0 intf all proto rip egp egpmetric 3
With only these four ``announce'' clauses in the configuration file,
gated will only announce these four nets. It will announce 128.84.0.0
via RIP and HELLO to all interfaces and announce it via EGP with a metric
of 0. Net 10.0.0.0 will be announced via RIP to all interfaces. Net
0.0.0.0 (default) will be announced by RIP out interface 128.84.253.200
only. Net 35.0.0.0 will be announced via RIP to all interfaces and
announced via EGP with a metric of 3. These are the only nets that will
be broadcast by this gateway. Once the first ``announce'' clause is
specified, only the nets with ``announce'' clauses will be broadcast;
this includes local subnets. Once an ``announce{host}'' or
``noannounce{host}'' has an ``all'' specified after an ``intf'', that
clause is applied globally and the option of having per interface
restrictions is lost. If no routing announcement restrictions are
desired, ``announce'' clauses should not be used. All information
learned will then be propagated out. Please note that this has no affect
on the information to which gated listens. Any net that does not have an
``announce'' clause is still added to the kernel routing tables, but it
is not announced via any of the routing protocols. To stop nets from
being added to the kernel the ``donotlisten'' clause may be used.
announce 128.84 intf 128.59.2.1 proto rip
noannounce 128.84 intf 128.59.1.1 proto rip
The above clauses mean that on interface 128.59.2.1, only information
about 128.84.0.0 will be announced via RIP, but on interface 128.59.1.1,
all information will be announced, except 128.84.0.0 via RIP.
noannounce 128.84 intf all proto rip hello egp egpmetric 0
noannounce 10.0.0.0 intf all proto hello
These clauses mean that except for the two specified nets, all nets will
be propagated. Specifically, net 128.84.0.0 will not be announced on any
interface via any protocols. Knowledge of 128.84.0.0 is not sent
anywhere. Net 10.0.0.0 will not be announced via HELLO to any interface.
This also implies that net 10.0.0.0 will be announced to every interface
via RIP. This net will also be broadcast via EGP with a metric specified
in the ``defaultegpmetric'' clause.
defaultegpmetric #
This is a default EGP metric to use when there are no routing
restrictions. Normally, with no routing restrictions, gated announces
all networks learned via HELLO or RIP via EGP with this specified default
EGP metric. If this clause is not used, the default EGP metric is set to
255, which would make any EGP advertised route of this nature be ignored.
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When there are no routing restrictions, any network with a direct
interface is announced via EGP with a metric of 0. Note that this does
not include subnets, but only the non-subnetted network.
defaultgateway gateway proto [metric metric] {active|passive}
This default gateway is installed in the kernel routing tables during
initialization and reinstalled whenever information about the default
route is lost. This route is installed with the time delay equivalent of
a RIP metric of 15 unless another metric is specified with the metric
option.
If `RIP gateway' or `HELLO gateway' are in use this default route is
deleted when successfully peering with an EGP neighbor not specified for
``nogendefault''.
An ``active'' default route will be overridden by any other default route
learned via another routing protocol. A ``passive'' default route will
only be overridden by a default route with a lower metric.
An ``active'' default route will not be propagated in routing updates, a
``passive'' default route will be propagated.
``gateway'' should be an address in dot notation. ``metric'' is optional
and should be a metric in the specified protocol between zero and
infinity, if not specified a RIP metric of 15 is used. ``proto'' should
be either ``rip'', ``egp'', or ``hello''. The ``proto'' field
initializes the protocol by which the route was learned. Although in
this case it is unused, but the field is remains for consistency.
net netaddr gateway addr metric hopcnt {rip|egp|hello}
host hostaddr gateway addr metric hopcnt {rip|egp|hello}
The following clauses install a static route to net ``netaddr'' or host
``hostaddr'' through gateway ``addr'' at a metric of ``hopcnt'' learned
via either RIP, HELLO, or EGP. As usual, dot notation is recommended for
the addresses. This route will be installed in the kernel's routing
table and will never be affected by any other gateway's RIP or HELLO
announcements. The protocol by which it was learned is important if the
route is to be announced via EGP. If the protocol is ``rip'' or
``hello'' and there are no routing restrictions, then this route will be
announced by EGP with a metric of ``defaultegpmetric''. If the protocol
is ``egp'' and there are no routing restrictions, then this route will be
announced by EGP with a metric of ``hopcnt''.
egpnetsreachable net [net] [net] .....
This option was left in as a ``soft restriction''. It cannot be used
when the ``announce'' or ``noannounce'' clauses are used. Normally, with
no restrictions, gated announces all routes learned from RIP and HELLO
via EGP. The ``egpnetsreachable'' clause restricts EGP announcement to
those nets listed in the clause. The metric used for the HELLO and RIP
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learned routes is the value given in the ``defaultegpmetric'' clause. If
this clause does not specify a value, the value is set to 255. With the
``egpnetsreachable'' clause, individual unique EGP metrics may not be set
for each net. The ``defaultegpmetric'' is used for all networks except
those that are directly connected, which use a metric of 0.
martiannets net [net] [net] ...
This clause appends to gated's list of ``martian'' networks. ``Martian''
networks are those known to be invalid and should be ignored. When gated
hears about one of these networks through any means, it will immediately
ignore it. If ``external'' tracing is enabled, a message will be printed
to the trace log. Multiple occurrences of the ``martiannets'' clause
accumulate.
An initial list of ``martian'' networks is coded into gated. This list
contains 127.0.0.0, 128.0.0.0, 191.253.0.0, 192.0.0.0, 223.255.255.0, and
224.0.0.0.
CONFIGURATION FILE OPTIONS FOR AUTONOMOUS SYSTEM ROUTING
In the internal routing tables, gated maintains the autonomous system
number from which each route was learned. Autonomous systems are used
only when an exterior routing protocol is in use, in this case EGP.
Routes are tagged with the autonomous system number of the EGP peer from
which they were learned. Routes learned via the interior routing
protocols, RIP and HELLO, are tagged with the autonomous system number
specified in the ``autonomoussystem'' clause.
Gated normally does not propagate routes learned from exterior routing
protocols to interior routing protocols. Historically this is because of
the ARPANET core EGP speakers which do not have adequate validation of
routing information they receive. Some of the following clauses allow
exterior routes to be propagated via interior protocols. Therefore it is
imperative that utmost care be taken when allowing the propagation of
exterior routes.
The following clauses provide limited control over routing based on
autonomous system number.
validAS net AS as metric metric
The ``validAS'' clause is used for validation of networks from certain
AS. When an EGP update is received from a neighbor which has the
``validate'' option specified on the associated ``egpneighbor'' clause a
``validAS'' clause is searched for specifying that network and the
autonomous system number of the EGP neighbor. If the appropriate
``validAS'' clause is located, the network is considered for addition to
the routing table with the specified metric. If a ``validAS'' clause is
not located, a warning message is printed and the network is ignored.
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GATED(1M)GATED(1M)
A network may be specified in several ``validAS'' clauses as being
associated with several different autonomous systems.
announcetoAS as0 {restrict|norestrict} ASlist as1 as2 as3 ...
noannouncetoAS as0 {restrict|norestrict} ASlist as1 as2 as3 ...
The ``announcetoAS'' and ``noannouncetoAS'' control the exchanging of
routing information between different autonomous systems. Normally gated
will not propagate routing information between autonomous systems. The
exception to this is that routes learned from gated's own autonomous
system via RIP and HELLO will be propagated via EGP. These clauses allow
information learned via EGP from one autonomous system to be propagated
via EGP to another autonomous system or via RIP and HELLO to gated's own
autonomous system.
If the ``announcetoAS'' clause is specified, information learned via EGP
from autonomous systems as1, as2, as3, ... will be propagated to
autonomous system as0. If gated's own autonomous system, as specified in
the ``autonomoussystem'' clause, is specified as as0, this information
will be propagated via RIP and HELLO. Routing information from
autonomous systems not specified in the ASlist will not be propagated to
autonomous system as0.
If the ``noannouncetoAS'' clause is specified, information learned via
EGP from all autonomous systems except as1, as2, as3, ... will be
propagated to autonomous systems as0. If gated's own autonomous system
is specified as as0, this information will not be propagated via RIP and
HELLO.
The ``[no]restrict'' option controls the application of ``announce'' and
``noannounce'' clauses to the propagation of routes to different
autonomous systems. If ``restrict'' is specified, normal announcement
restrictions do apply, if ``norestrict'' is specified, announcement
restrictions are not considered, all routes from the source autonomous
systems are propagated to the destination autonomous system.
Only one ``announcetoAS'' or ``noannounceAS'' clause may be specified per
target autonomous system.
NOTES ON CONFIGURATION OPTIONS
If EGP is being used when supplying the default route (via ``RIP
gateway'' or ``HELLO gateway'') and all EGP neighbors are lost, the
default route will not be advertised until at least one EGP neighbor is
regained.
With the complexity of the current network topology and with many back-
door paths to networks, the use of routing restrictions is recommended.
With the current routing strategies, it is easy for illegal or invalid
networks to penetrate into the ARPAnet Core or the NSFnet backbone.
Using routing restrictions does take a little more maintenance time and
routing restrictions are not the long term answer, but, for now, in order
to be good Internet players, we must use them.
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GATED(1M)GATED(1M)GATED INTERNAL METRICS
Gated stores all metrics internally as a time delay in milliseconds to
preserve the granularity of HELLO time delays. The internal delay ranges
from 0 to 30000 milliseconds with 30000 representing infinity. Metrics
from other protocols are translated to and from a time delay as they are
received and transmitted. EGP distances are not comparable to HELLO and
RIP metrics but are stored as a time delay internally for comparison with
other EGP metrics. The conversion factor between EGP distances and time
delays is 100. RIP and interface metrics are translated to and from the
internal time delays with the use of the following translation tables:
Time Delay RIP metric RIP metric Time Delay
0 - 0 0 0 0
1 - 100 1 1 100
101 - 148 2 2 148
149 - 219 3 3 219
220 - 325 4 4 325
326 - 481 5 5 481
482 - 713 6 6 713
714 - 1057 7 7 1057
1058 - 1567 8 8 1567
1568 - 2322 9 9 2322
2323 - 3440 10 10 3440
3441 - 5097 11 11 5097
5098 - 7552 12 12 7552
7553 - 11190 13 13 11190
11191 - 16579 14 14 16579
16580 - 24564 15 15 24564
24565 - 30000 16 16 30000
NOTES ON IMPLEMENTATION SPECIFICS
In the gated configuration file, all references to POINT-TO-POINT
interfaces must use the DESTINATION address.
All protocols have a two minute hold down. When a routing update
indicates that the route in use is being deleted, gated will not delete
the route for two minutes.
Changes can be made to the interfaces and gated will notice them without
having to restart the process. If the netmask, subnetmask, broadcast
address, or interface metric are changed, the interface should be marked
down with ifconfig(1M), then marked up at least thirty seconds later.
Flag changes do not require the interface to be brought down and back up.
RIP propagates and listens to host routes, thus allowing the consistent
handling of PTP links. The RIP_TRACE commands are also supported.
Subnet interfaces are supported. Subnet information will only be
propagated on interfaces to other subnets of the same network. For
example, if there is a gateway between two class B networks, the subnet
routes for each respective class B net are not propagated into the other
class B net. Just the class B network number is propagated.
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GATED(1M)GATED(1M)
Gated listens to host and network REDIRECTs and tries to take an action
on the REDIRECT for its own internal tables that parallels the kernel's
action. In this way, the redirect routine in gated parallels the
Berkeley kernel redirect routine as closely as possible. Unlike the
Berkeley kernel, gated times out routes learned via a REDIRECT after six
minutes. The route is then deleted from the kernel routing tables. This
helps keep the routing tables more consistent. Any route that was
learned via a REDIRECT is NOT announced by any routing protocol.
The gated EGP code verifies that all nets sent and received are valid
class A, B or C networks per the EGP specification. Information about
networks that do not meet these criteria is not propagated. If an EGP
update packet contains information about a network that is not either
class A, B or C, the update is considered to be in error and is ignored.
FILES
/usr/etc/gated.conf configuration file.
/usr/tmp/gated_dump memory dump file
/usr/etc/gated gated itself
SEE ALSOrouted(1M)
RFC827 EXTERIOR GATEWAY PROTOCOL (EGP)
RFC888 "STUB" EXTERIOR GATEWAY PROTOCOL
RFC891 DCN Local-Network Protocols (HELLO)
RFC904 Exterior Gateway Protocol Formal Specification
RFC911 EGP GATEWAY UNDER BERKELEY UNIX 4.2
CREDITS
This program was derived from Paul Kirton's EGP for UNIX, UC at
Berkeley's routed(1M), and HELLO routines by Mike Petry at the University
of Maryland.
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