RIPV2 with Basic Authentication
Loopback Interfaces:
The Loopback interfaces are representing our networks behind the router itself that faces the outside world.
Key Chain
When making the key chain we will call it RIPV2 we can call it anything we want like NICKSKEY, spurs, or anything you can think of really.
**** Remember after creating the key we have to enable it on the interface that is advertising RIP traffic ! not inside the router rip configuration itself!
A good analogy of this is think of a cook in the kitchen when you're going to a restaurant. The cook has all the utensils and "networks" to get the job done and make the all the meals in his kitchen ( in our case keep the networks inside our RIP configuration) BUT who does the advertising or talking? Its the waitress or the interface talking to other networks! So the waitress or the "interface" has to know of the authentication being advertised so the cook in the kitchen can deliver the meals ( networks) to the correct person or in this case to the correct router !
172.16.16.0 Network
Each 172.X.X.X network on the interfaces of each router represent the public or "outer-facing" connections to other networks.
R3:
This router in the topology will NOT be able to authenticate with R1 or R2
The configuration :
R1:
key chain RIPV2 ( This will start the making of the key chain "whatever name you want")
key 1 ( The key number 0 through 2147483647 )
key-string cisco ( The key string is the password or "string" this can be unencrypted or encrypted )
interface Loopback0
ip address 1.1.1.1 255.255.255.0 ( Represent a network behind the router )
!
interface Loopback1
ip address 11.11.11.1 255.255.255.0
!
interface FastEthernet0/0
description Link to R3 ( Dont forget descriptions are always good!)
ip address 172.16.16.9 255.255.255.252
ip rip authentication mode md5 ( Enabling of rip authentication using MD5 HASH/Digest)
ip rip authentication key-chain RIPV2 ( Enabling the key chain we want to use..in this case its the key we made beforehand called RIPV2 )
duplex auto
speed auto
no shutdown ( Remember to do a no shutdown to turn the interface ON )
!
interface FastEthernet0/1
description Link to R2
ip address 172.16.16.1 255.255.255.252
ip rip authentication mode md5
ip rip authentication key-chain RIPV2
duplex auto
speed auto
no shutdown
RIP CONFIGURATION
router rip ( enters rip configuration )
version 2 ( we want version 2 not 1 )
network 172.16.0.0 ( remember rip will show the network as classful so we just keep it simple and do the classful range which will cover all the interfaces going to R2 and R3 instead of putting in two)
network 1.0.0.0
network 11.0.0.0
no auto-summary ( We can auto-summarize the networks so that they show up in the routing table as only advertising the /30's and /24's and not an entire /16 or /8 subnet !)
R2:
key chain RIPV2
key 1
key-string cisco
interface Loopback0
ip address 2.2.2.1 255.255.255.0
!
interface Loopback1
ip address 22.22.22.1 255.255.255.0
!
interface FastEthernet0/0
description Link to R1
ip address 172.16.16.2 255.255.255.252
ip rip authentication mode md5
ip rip authentication key-chain RIPV2
duplex auto
speed auto
!
interface FastEthernet0/1
description Link to R3
ip address 172.16.16.5 255.255.255.252
ip rip authentication mode md5
ip rip authentication key-chain RIPV2
duplex auto
speed auto
!
router rip
version 2
network 2.0.0.0
network 22.0.0.0
network 172.16.0.0
no auto-summary
R3:
*****This router will not have authentication to show that the routes will not be seen by R1 or R2
interface Loopback0
ip address 3.3.3.1 255.255.255.0
!
interface Loopback1
ip address 33.33.33.1 255.255.255.0
!
interface FastEthernet0/0
description Link to R1
ip address 172.16.16.10 255.255.255.252
duplex auto
speed auto
!
interface FastEthernet0/1
description Link to R2
ip address 172.16.16.6 255.255.255.252
duplex auto
speed auto
!
router rip
version 2
network 3.0.0.0
network 33.0.0.0
network 172.16.0.0
no auto-summary
So now the network is configured we should see the following on Router 1:
R1#sh ip route
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
2.0.0.0/24 is subnetted, 1 subnets
R 2.2.2.0 [120/1] via 172.16.16.2, 00:00:21, FastEthernet0/1
172.16.0.0/30 is subnetted, 3 subnets
C 172.16.16.8 is directly connected, FastEthernet0/0
R 172.16.16.4 [120/1] via 172.16.16.2, 00:00:21, FastEthernet0/1
C 172.16.16.0 is directly connected, FastEthernet0/1
22.0.0.0/24 is subnetted, 1 subnets
R 22.22.22.0 [120/1] via 172.16.16.2, 00:00:22, FastEthernet0/1
11.0.0.0/24 is subnetted, 1 subnets
C 11.11.11.0 is directly connected, Loopback1
We see both R1 networks and R2 networks BUT we do not see R3. This is because R3 does not have authentication. So we are going to do a debug to show what R3 is seeing when it advertises out to R1 and R2:
R3# debug ip rip
*Mar 1 01:03:45.695: RIP: sending v2 update to 224.0.0.9 via FastEthernet0/0 (172.16.16.10)
*Mar 1 01:03:45.695: RIP: build update entries
*Mar 1 01:03:45.695: 3.3.3.0/24 via 0.0.0.0, metric 1, tag 0
*Mar 1 01:03:45.699: 33.33.33.0/24 via 0.0.0.0, metric 1, tag 0
*Mar 1 01:03:45.699: 172.16.16.4/30 via 0.0.0.0, metric 1, tag 0
Router 3 knows of all its own networks but not R2 or R1's
R3#
*Mar 1 01:03:50.919: RIP: ignored v2 packet from 172.16.16.9 (invalid authentication)
It ignores the multicast advertisement because of invalid authentication no key passwords are being exchanged in this case we don't have the "waitress"
R3#
*Mar 1 01:03:55.939: RIP: ignored v2 packet from 172.16.16.5 (invalid authentication)
Again the packets are ignored because the authentication is invalid we need the password to get the information
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