So what are you doing in this example the source address translation.
We're not going to do destination address translation as source address translation tends to be the
most common implementation of MacT and that's what you need to know for the CCN a certification with
source address translation you're typically netting devices on your internal network that use our FC
19:18 addresses for those devices to access devices on the Internet their addresses need to be translated
or changed from an RF see 19:18 address to a publicly readable address.
In this example the router has an IP address of 1.1 but one to one and we are going to not host 10 wondered
one but one to an IP address of one that one that one but two.
So in this example we not netting the PCs IP address to the routers IP address.
I'll show you that example in a moment.
In this example we are enacting one internal IP address or private IP address to a dedicated public
IP address.
In this example we've also got a server on internet with an IP address of to to to to to to to.
So the Rodda will populate to the next table as follows.
Inside a local address is tendered.
Wondered.
One inside global is one that one one to a T outside local and outside global are set to to to to to
to talk to.
In this example we not netting the outside address we are only getting the inside address if you are
sniffing this local area network connection between the PC and the router using Y shock and I'm going
to demonstrate that in a moment what you would see is that the source address of the packet is set to
10 to 1 to 1 to 1.
That's the physical IP address of the host the destination address for Traffic is to to to to to to
a T.
In other words the PC has initiated a session to the server.
And if you capture traffic on the local network so addresses the PC's actual IP address and destination
address is the servers IP address.
However when the traffic hits the router the Radu will look in the NAT table because it's receiving
traffic on an inside interface which you configure and the traffic is destined to an outside interface.
So you configure the Rodda with the inside and outside interfaces.
And because of that configuration the router looks in the next table to see if addresses should be noted
in this case the source IP address matches an entry in the table.
So the source IP address is going to be changed to one that won that one but to the destination address
is not going to be changed it's going to remain as two toe to toe to toe to the right will change the
source address.
And then for the traffic to the Internet the source address matches the same tree of ten that wandered
one one and the destination address matches this entry to to to to to to to.
So the router is going to change the source IP address to 1.1 but one to two has per the inside global
entry in the NAT table.
In this example the outside local and outside global addresses are the same.
So the router doesn't change the destination address in the packet.
If you sniffed the traffic using wireshark on this link from the router to the internet you would see
that the source address is set now to 1.1 but one to two rather than 10.
One but one but one which it was said to you on the inside network when the traffic arrives at the server
and the server receives the traffic the server believes that it's talking with a host with an IP address
of 1.1 but one to two the server never sees that the actual source IP address was tendered wondered
wondered one when the server replies the source and destination addresses are swapped around.
So the source address is now to to to to to to a T and the destination address is now.
Wondered.
Wondered wonder tea.
The packet is now routed across the Internet and arrives at the NAT router.
When the router receives the traffic it sees that the traffic is destined to not be address of 1.1 but
wander to the road it will check in its NOT table whether it has a matching entry.
In this case it does the inside global address.
He's wondered wondered wonder too which matches the destination address.
So what the router will do is it will not.
The IP address.
Wonder wonder wonder.
T and change it to 10.
That one that one but one before forwarding the traffic on to the local network.
The source address of people too is not changed because those entries are the same in the net table
for outside local and outside global.
So once again if you sniffed the traffic between the route and the PC you would see that the destination
address is tendered wondered wondered one source or races to to to to to to t.
And that's because the router has changed the destination IP address based on the inside local entry.
Now that's essentially how that works.
This is a simple one to one mapping with basic Nat.