So exit out of the Telnet session from rather three four rather one two, rather three and we can see
some net translations taking place.
Show IP net translation.
We can see our two net translations in the table, which will time out after a period of time.
Wrote a four.
I'll also exit out of the Telnet session.
Currently we've got those two natural translation entries.
Let's do a Y shock capture.
So I'm going to capture on the outside interface.
And in this case, let's look at what's arriving at router three.
So what's arriving on that port?
I'm going to filter this for Telnet.
And on writer one I'll telnet to router three.
We can see the Telnet data.
So.
Some Telnet negotiation taking place and we being prompted for our password.
So we see this in the Wireshark capture.
What I'll do is enter a password of Cisco and log in.
And here you can see.
See?
I see.
Oh, there's the Cisco login password.
But what's important to notice is the traffic is coming from a source of 8 to 1 one one going to 8112.
So it looks like or appears like the traffic is coming from this host going to this host, whereas in
actual fact, the traffic is coming from our one.
But in the wide shot capture, we can see that all the communication is between 8112 and 8111.
So in this example, a root of three prompt is being sent from router three to router one.
Let's stop that capture.
And have a look at it on this side.
So I'll have a look at it on the switch.
So on this part of the network here.
I'll do a photo for Telnet once again and I'll exit out of the Telnet session.
Notice this was still part of the same Telnet session.
But notice now the address is from ten 11128112.
His E.
X.
I.
T.
Exit.
And then we have this session closed.
So in this example, the traffic is from this IP address as the source to this IP address is the destination.
But when it's on this interface, it's changed to 8111.
So that's an example of Pat in real time.
Let's do it with two devices.
I'll do the caption now on this side, but have two talented sessions going at the same time.
So Telnet.
Rather one telnet to router three.
And rather for telnet to router three.
Notice on all the output you only see 8111 communicating with 8112.
You don't see.
That the communication is actually from writer one and of four and all the output.
It looks like it's the same two devices communicating with each other.
Whereas in actual fact, there are multiple devices communicating here.
And not just a single source device talking to a single destination device.
Now you can see that by looking at the port numbers.
So for this session, the port number is 19207.
So that's part of the same session.
19207.
But notice here, it's a different session.
Number 3245732457.
If we look at the net translations show IP net translation, we can see the actual port numbers used
by the devices in the sessions.
So three, two, four, five, seven.
Scrolling down 19 to oh seven.
So there's the first device, ten 111 and yes, the second 110 114.
That's once again how the right is able to differentiate between the devices.
Let's have a look at verbose output in the show.
IP net translations verbose output.
We can see when it was created.
So this one was created 2 minutes and 38 seconds ago, this one, 2 minutes and 34 seconds ago.
You can see the use and the timeout and what's left on these entries.
What's important to remember for dynamic net translations such as this is that multiple internal IP
addresses are being mated to a single external IP address.
You mustn't forget.
To include the overload keyword.
If you forget that keyword, only one device will be able to access the internet.
Overloading enables pat or port address translation, which allows multiple internal devices to share
the same global IP address and the router that's doing the net or in this case, port address translation
or Pat can differentiate between the sessions based on the port numbers.