Nat, Nat Overload & PAT? Please help!!

ralbertos21

I understand that NAT enables you to use a private IP address from a LAN and translates an IP address into a public one when accessing the internet...

I am still confused on what the purpose of NAT Overload means.. does that convert many LAN IP addresses into one Public IP address so it can be usable on the Internet?

PAT??? I have no clue what this is ...

How did you all learn
Inside local/Outside local
Inside global/Oustide global ??

deth1k

NAT overload is PAT, meaning port address translation.

ralbertos21

So NAT overload is PAT then... okay so my question now is why do they refer it to as "overloading?"



Thanks

deth1k

Well, that's just Cisco way of configuring it and calling it an "overload".

xenodamus

I think of it as "overloading" that 1 public IP address with translations from a bunch of private ones using port numbers. As far as what PAT is, think about this -

When you use NAT to translate an inside address to an outside address it takes 1 of each...as in:

Inside 10.0.0.1 > Outside 65.5.53.216
Inside 10.0.0.2 > Outside 65.5.53.217
Inside 10.0.0.3 > Outside 65.5.53.218

The purpose of PAT is to use port numbers to translate multiple inside addresses using 1 public address:

Inside 10.0.0.1 > Outside 65.5.53.216:25000
Inside 10.0.0.2 > Outside 65.5.53.216:26000
Inside 10.0.0.3 > Outside 65.5.53.216:27000

That way everyone on the inside network can be publicly routable using a single IP. Much more efficient use of the dwindling IPv4 address space.

instant000

Please review this thread. It should clear up your questions.

http://www.techexams.net/forums/security/88883-pat-nat-dnat-how-tell-one.html

d6bmg

Remember this sequence: Inside local -> Inside Global ----> Internet ----> Outside Global -> Outside Local (optional)
This is the sequence of data flow.

ralbertos21

xenodamus wrote: »

I think of it as "overloading" that 1 public IP address with translations from a bunch of private ones using port numbers. As far as what PAT is, think about this -

When you use NAT to translate an inside address to an outside address it takes 1 of each...as in:

Inside 10.0.0.1 > Outside 65.5.53.216
Inside 10.0.0.2 > Outside 65.5.53.217
Inside 10.0.0.3 > Outside 65.5.53.218

The purpose of PAT is to use port numbers to translate multiple inside addresses using 1 public address:

Inside 10.0.0.1 > Outside 65.5.53.216:25000
Inside 10.0.0.2 > Outside 65.5.53.216:26000
Inside 10.0.0.3 > Outside 65.5.53.216:27000

That way everyone on the inside network can be publicly routable using a single IP. Much more efficient use of the dwindling IPv4 address space.

You couldn't of explained this any better my friend, wow great stuff! Now i see the picture

ralbertos21

instant000 wrote: »

Please review this thread. It should clear up your questions.

http://www.techexams.net/forums/security/88883-pat-nat-dnat-how-tell-one.html

awesome thread just read it