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NOSVIEW
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ROUTE
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1992-12-31
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===== NOSview [301]
route
=====
_________________________________________________________________
route
_________________________________________________________________
Display the IP routing table.
>> Example of a 'route' display output:
..............................................................
: Dest Len Interface Gateway Metric P Timer Use :
: uk 32 tnc0 1 P man 1 :
: ns9liz 32 tnc0 ns9gwb 1 man 3 :
: region42 24 tnc0 ns9gwa 1 man 0 :
: 192.1.2.0 24 sl0 1 P man 0 :
: region41 24 tnc0 ns9bob 1 P man 0 :
: default 0 tnc0 1 P man 4 :
:............................................................:
The 'P' entries are private entries which are not distributed to
other hosts.
_________________________________________________________________
route add <target_host>[/bits] | default <interface>
[<gateway_host>[<metric>]]
_________________________________________________________________
The 'route add' command adds an entry to the routing table. It
requires at least two more arguments: the target host and the
name of the interface to which its packets should be sent.
If the target is not local, the gateway should also be specified.
(If the interface is a point-to-point link, then <gateway_host>
may be omitted even if the target is non-local, because this
field is only used to determine the gateway's link level address,
if any).
If the destination is directly reachable, <gateway_host> is also
unnecessary since the destination address is used to determine
the interface link address.
The optional '/bits' suffix to <target_host> specifies how many
leading bits in the host IP address are to be considered
significant in the routing comparisons. If not specified, 32
bits (i.e. full significance) is assumed.
With this option, a single routing table entry may refer to many
hosts all sharing a common bit string prefix in their IP
addresses. For example, ARPA Class A, B and C networks would use
suffixes of /8, /16 and /24 respectively. Hence the command
'route add 44/8 sl0 44.64.0.2' causes any IP addresses beginning
with '44' in the first 8 bits to be routed to 44.64.0.2; the
remaining 24 bits are "don't-cares".
To make displayed reports more meaningful, subnets can be given
names in /domain.txt, and then used in the 'route' command. For
example, if "region42" is defined as "44.191.42.0" in the hosts
file, you can then give a command of the form 'route add
region42/24 ...'
When an IP address to be routed matches more than one entry in
the routing table, the entry with largest bits parameter (i.e.
the "best" match) is used. This allows individual hosts or
blocks of hosts to be exceptions to a more general rule for a
larger block of hosts.
The special target 'default' is used to route datagrams to
addresses not matched by any other entries in the routing table;
it is equivalent to specifying a '/bits' suffix of '/0'. Care
must be taken with 'default' entries since two nodes with default
entries pointing at each other will route packets to unknown
addresses back and forth in a loop until their time-to-live (TTL)
fields expire. (Routing loops for specific addresses can also be
created, but this is less likely to occur accidentally).
>> Examples: route add default en0 192.5.6.7
route add 44.191.42.0/24 tnc0 ns9gwa
route add region42/24 tnc0 ns9gwa
route add default tnc0
route add ns9jim tnc0
route add 192.3.4.5 sl0 (no gateway, as SLIP is
point-to-point)
_________________________________________________________________
route addprivate <target_host>[/bits] | default <interface>
[<gateway_host> [<metric>]]
_________________________________________________________________
The 'route addprivate' command is identical to 'route add' except
that it also marks the new entry as private; it will never be
included in outgoing RIP updates.
>> Example: route addprivate region41/24 ns9bob
_________________________________________________________________
route drop <target_host>[/bits]
_________________________________________________________________
The 'route drop' command deletes an entry from the table. If a
packet arrives for the deleted address and a default route is in
effect, it will be used.
>> Examples: route drop ns9liz
route drop region42/24
_________________________________________________________________
route flush
_________________________________________________________________
Remove all automatically-entered entries from the IP routing
table.
_________________________________________________________________
route lookup <target_host>
_________________________________________________________________
Display the routing table entry for <target_host>.
>> Examples: route lookup region42
route lookup ns9liz
There are two built-in interfaces: loopback and encap.
Loopback is for internal purposes only.
The encap is an IP encapsulator interface. This is used to
encapsulate a complete IP datagram into an IP datagram so that it
gets "piggy-backed". It is often used to carry AMPRnet datagrams
over the Internet. This way two sites can interchange AMPRnet
datagrams with each other.
Some extra notes: An Internet gateway has 2 IP addresses: one on
AMPRnet and one on the Internet. You should make sure that the
interface connected to the Internet has the 'ifconfig ipaddr' set
correctly. Note: This previously only worked as gateway for
other stations. There was some guessing done in picking an IP
address when encap is used localy. The guessing takes the worst
guess. The code now uses the local IP address as source when the
route starts at the local station. If this is not what you want,
you can overrule this by setting the IP address of the pseudo-
encap interface to what you want it to be.
[Additional notes from PA0GRI: I have 3 systems on an Ethernet
with network 129.179.122.128/25. In the office I have another
net linked to the Internet. The addresses there are in the
129.179.122.0/25 range. Now I have a radio link with 44.137.0.2
and 44.137.1.2 on respective sites. On the 44.137.0.2 system I
have 'route add 44.0.0.0/8 encap 44.137.1.1 99'. On a next
system on my local Ethernet I have 44.137.0.1 / 129.179.122.129.
To get from that system to say 44.62.0.1 I have to add an encap
to my local gateway with:
'route add 44.0.0.0/8 encap 129.179.122.130'.
A 'route add default ec0 129.179.122.130' gives me access to the
Internet. Otherwise it will lookup the address for the interface
to be used to reach 129.179.122.130 and will use 129.179.122.129.
Now 44.62.0.1 will NEVER know where it came from. So
adding the encap on the second system solves the problem].