Configuring PAT/NAT in cisco routers

Question

hello, first sorry for my bad english
i just wanted to know how configuring PAT (port address translation)
like this :?
amir(config)#ip nat inside source static tcp 192.168.1.1 1000 172.16.1.1 1000
or not?
2nd question i have is:
when i need to write: "ip nat inside source"... and when i need to write "ip nat outside" ..
and the last question for now is:
how i can (if that's possible) to configure dynamic PAT - I mean that any computer on my LAN will go out to the internet with the same address but with diffrent ports - in random mode.(i mean without configuring static one by one)
i hope i was clear enough, tanks a lot!

Answer 1

Hi Tiger,
1) Yes your first statement is a static PAT statement which will say source ip with source port 1000 is translated to 172.16.1.1 with same port number but yes it is a static PAT entry.
2) Coming to your 2nd question
"ip nat inside source" is a global config command which says any traffic which hits the inside interface nat the source ip address.
"ip nat inside" is a interface mode command which should be done going to any interface. This command specifies which will be an inside interface which will nat the incoming traffic.
3) Coming to your last question
For dynamic PAT you just need to configure overload command at the end of your nat statement.
This link will give you a very broad and nice picture of how NAT can be configured in different situation
http://www.cisco.com/warp/public/556/12.html#6
HTH
Ankur