Introduction to IT and Cybersecurity
Video Description
Cisco Discovery Protocol Lab Our next lesson explains the proprietary protocol Cisco Discovery Protocol. The purpose of this protocol is to map out your network and why it should be turned off in a secure environment. You'll learn its default settings, how to run and configure it, what its output reveals and what can be done with the information displayed.
Video Transcription
00:04
the next topic of discussion is a very sharp topic, and it deals with Cisco Discovery Protocol.
00:11
Cisco Discovery Protocol is a layer to protocol that is used to map out your network.
00:17
Now the words map out. Your network should set. Send warning bells in your head because insecure environments
00:25
you should not allow people to map out your network. So this protocol should be turned off
00:31
if you are in a secure environment, which
00:34
most of the time happens In the DC Washington metro area,
00:39
However,
00:43
CDP works between devices.
00:46
It is Cisco proprietary and on by default.
00:50
So if I go on rather one
00:52
and CDP is on by default
00:55
and if I say execute the command
00:58
show CDP neighbors,
01:02
I see if physically you see look at art apology. You see a router two or one
01:11
is connected to a router. One
01:14
on router to one serial 0102 rather one serial 000
01:19
So if I go into outer one and execute the show CDP neighbor command or neighbors command,
01:26
I see the device i d of the device at the other end, which is rather one
01:32
my local interfere serial 010
01:36
is connected to serial 000 off router one.
01:42
So my router to one serial 010 is connected to serial 000 on router one.
01:51
The platform on Router one is a C 2800 series router.
01:56
If I execute the command Sure. CDP neighbor detail, neighbors detail.
02:01
I see a little bit more detail about Router one.
02:05
Router one is running version 12.4
02:09
sub release 15 T operating system.
02:15
My interface serial 010
02:20
is connected to
02:22
robber ones.
02:23
Serial 000
02:27
The platform ISS see 2800 series router
02:30
and I also see rowdier ones I p. Address, which is 200. 202 100.1
02:38
to show you that router ones I p address on serial 000 is actually 202 102 101.
02:45
I can go into Router One and execute the
02:50
you shou ID be inter fees,
02:53
brief command. And as you see, serial 000 on Router one. Has I p 201 11
03:00
now a variation of the show
03:05
CDP neighbors detail command because this one sure, you detailed information about all the devices you are connected to.
03:13
So if I execute this command on router one, it won't be as clean or if I execute this command. Yes, on router one.
03:23
Sure CDP neighbors detail.
03:27
I see detail about switch one
03:30
so router ones interface faceted at 00 is connected to switch ones. Fast. Ethan at Zito's Last 24
03:38
and the switch is a 35 60. Switch running
03:43
operating system version. $12 to sub release. 37 s e.
03:47
And I see information about rotter to a one, which is connected on the other side. On serial 000 router to one's address is 202 102 102
03:59
router ones into face 0000 is connected to
04:02
router to one's interface. Hero 010 and router to one is a C 2800.
04:11
See 2800 studies router
04:15
Now what if I just wanted to see you out? Or to a one? Variations of the shore CDB neighbor detail command is show CDP entry
04:27
are to a one are to a one being are two router to a one's host name
04:32
and hit enter. Then it would show me information Just about our to a one
04:38
and set off all my neighbors.
04:42
Another variation of the shore CDP neighbor detail Command is sure CDP
04:46
entry
04:48
show CDP Entry star which stands for Show all my entries once again similar to the show CDP Neighbor Detail command, you see switch one and router to a one, which is on the cereal and over our one
05:05
again. It showed me information about which one
05:10
and our to a one
05:12
Which one is connected to our one on fast Internet 00 locally and
05:18
fast. Lieutenant zero slash 24 on the switch in
05:21
and our two alone disconnected
05:26
on s 000
05:28
on our one to our two ones as 010
05:32
Now, as I said, you should turn off CDP if you are in a secure environment so I could go to interferes. Fascinating that 00 and say no
05:45
cdp
05:46
enable. That turns off CDP on my fastest in at 00 interface which is connected to switch one. Now if I ask for
05:59
let's clear the CDP table for us
06:02
with this Claire CDB table command. Now, if I look at show cdp
06:11
neighbor detail
06:15
I don't see anything because CDP has not talked back and forth yet.
06:23
Let me bounce the interfaces.
06:27
Let me just reload this router real quick to hasten the process. I saved my work with the W R Command and reloaded the router.
06:38
You would not do this at work. I'm just trying to hasten the process of the lab
06:44
show CDP neighbor detail
06:49
That seems to have turned off CDP on all the interfaces.
06:57
Okay, we will go back a little bit.
07:00
No, we can keep rolling.
07:01
So as I said that in a secure environment, CDP should be turned off
07:08
on your devices.
07:11
You could
07:13
either
07:14
go into an interface and say
07:16
no CDP unable to turn our CDP per interface.
07:21
Or you could say no CDP run
07:27
from config motew globally turnoff CDP on that device.
07:31
Now, if execute the command show CDP neighbor,
07:39
I hear or I get a message saying CDP is not enabled.
07:44
This concludes our CDP lecture
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