Now to connect to GNS3 I need to connect the switch to this cloud.
It's basically bridging the GNS3 network to my physical network.
So I've created a connection between the virtual and the physical network that'll allow this phone to
register.
Now, it may take a while to register, but once it's registered, I should be able to make calls from
the physical phone to the virtual phones in my GNS3 topology.
Here's the GNS3 router so show ePhone at the moment, it says that the third phone has registered.
It's a 7970.
It's got this IP address, it's got this telephone number.
So I should, in theory, be able to make calls from my physical phone to these virtual phones.
So let's try that together, so hopefully you can see that I'm going to go for.
I can hear the phone dial tone/
I'll dial 1001 notice over there, you can see the phone is ringing.
So I've got a call from a physical phone to a virtual phone.
Well, go talk here.
So there's a bit of delay, but again, you don't typically talk to yourself
and have phones that are so close to each other.
This is a call from a physical phone to a virtual phone.
OK, but what we actually want to do is, is use Wireshark to capture that so I'm gonna capture traffic
between the physical network and the virtual GNS3 network.
So Wireshark is capturing there's a lot of traffic on this network, so I'll keep it fairly short
and make the call again.
So dial tone.
You hear the phone ringing, I'll answer the phone.
This is a call from a physical phone to a virtual phone testing
1 2 3.
My name is David Bombal and I'm talking to myself.
It's not strange at all.
Bye
OK, call has ended.
I'll stop that
capture in Wireshark.
Now you can filter in Wireshark.
You can see there's a lot of other traffic here, like Dropbox synching, stuff like that happening
but what we actually want to look for is some UDP traffic that looks like this.
Traffic going from 10.1.1.120 to 10.1.1.1.
Now you might ask, how do you know that if you go to telephony, VoIP calls, you can see information
about calls here.
So as an example, you can see the call information from this IP address and the phone numbers.
So let's decode that as RTP
and click OK, again, you can see G7-11 ulaw, so that's the default protocol used by these
phones.
Go to telephony, RTP, RTP streams, there are the two streams.
I'll analyze that.
Click play streams.
Here are the streams.
This is a call from a physical phone to a virtual phone testing
1 2 3.
My name is David Bombal and I'm talking to myself.
So it's not strange at all.
Bye
So, again, I'm looking at both streams there.
If I go to telephony, RTP, RTP streams, I'll select.
The source phone, which is 10.1.1.120 and click analyze click play streams.
Now we only get the one stream rather than the
this is a call,, the reply from a physical phone to a virtual phone.
So yeah, you only get the original part of the audio rather than the duplication.
This is a call from a physical phone to a virtual phone testing
1 2 3.
My name is David Bombal and I'm talking to myself.
It's not strange at all.
OK, so that is an example of using Wireshark to capture voice calls and replay them between a physical
and a virtual phone.
What I'll do is save this file, and I've save the other one as well.
So that you can do this yourself.
So I'm gonna say audio physical.
Virtual ethical hack.
I'll stop this capture here.
So, again, what I've done is build a topology in GNS3 with some switches, a router which is acting
as a core manager or a Cisco unified communications manager, express router, in other words, allowing IP
phones to call each other.
And I've set up calls between virtual phones and set up calls between a virtual and physical phone.
I mean, just as a last step, I could call that physical phone from this virtual phone.
So here's my physical phone and I'll press three here, I'll cause myself deaf with my ringtone
but as you can see, it's ringing off the hook, testing.
This is a call from a virtual to physical phone,
and there you go.
So hopefully you enjoyed this video.
Let me know what other types of captures you'd like to see, in my Wireshark, course I do many
and I want to teach you how to capture traffic, how to analyze it.
Do you understand how ARP works?
Do you understand how spanning tree works?
Can you use Wireshark to analyze what's going on in the network?
Can you use Wireshark to look for problems?