Transcript .::Network Address Translation::. (NAT)

.::Network Address Translation::.
(NAT)
By
Tim Kaddoura
(CS158B // Dr. Stamp)
IP Address Allocation Overview
140
120
100
80
60
40
20
0
IPv4 IPv6

IPv4 Address
Type
IPv6 Address
Type


IPv4 – address
length is 4 bytes
long.
IPv6 – address
length is 16 bytes
long.
232 V.S 2128
Got NAT?!



NAT operates at the
network layer of the
OSI reference model
NAT is a hotel
receptionist
NAT allows for a
“one to one”,
“one to many”, or
“many to many”
mapping
NAT in Different Flavors




Static NAT: (one to one) from unregistered
(local) to registered (global).
Dynamic NAT: (one to one) similar to Static
Nat, but assigns from a pool of registered IP
addresses.
Overloading: (many to one) Most common
NAT at homes and small businesses.
Overlapping: (many to many) Most common
in organizations.
NAT Operation
GENERAL
View
Overloading
View
NAT Operation
(using a table)
Source Computer
Source Computer's IP
Address
Source Computer's
Port
NAT Router's IP
Address
NAT Router's Assigned
Port Number
A
192.168.32.10
400
215.37.32.203
1
B
192.168.32.13
50
215.37.32.203
2
C
192.168.32.15
3750
215.37.32.203
3
D
192.168.32.18
206
215.37.32.203
4
NAT and Built-In Security



NAT acts as a firewall.
Trudy will have trouble if she is outside
the network.
How about Trudy being inside the
network?!
NAT and SNMP



Problem, problem, and some more
problems!
SNMP’s crucial IP information is no
longer known.
Solution: IBM’s Comprehensive Network
Address Translator (CNAT).
To NAT or not to NAT!?

NAT is a good interim solution.

NAT is scalable.

NAT offers some security.

… To NAT!