Master the concepts of Network Address Translation (NAT) and Port Address Translation (PAT), essential for connecting private networks to the internet. Learn about static NAT, dynamic NAT, PAT/NAPT implementations, translation table management, and security configurations that enable secure network communication and address conservation.
Core concepts underlying NAT-PAT Implementation
NAT translates private IP addresses to public IP addresses, allowing multiple devices on a local network to share a single public IP address. This process involves modifying the IP header of packets as they traverse the NAT device.
Port Address Translation (PAT) extends NAT by also translating port numbers, allowing many internal hosts to share a single public IP address. Each connection is identified by a unique combination of IP address and port number.
Essential processes and techniques in NAT/PAT operation
One-to-one mapping between private and public IP addresses that remains constant
Mapping: Permanent
Use Case: Web servers, mail servers
Temporary mapping from private IP to public IP from a pool of addresses
Mapping: Temporary
Use Case: Limited public IP pool
Multiple private IPs mapped to single public IP using unique port numbers
Mapping: Many-to-One
Use Case: Home/office networks
Explore NAT-PAT concepts through advanced interactive visualizations
Simulate NAT/PAT configuration and packet translation processes
Manage PAT sessions and connection mappings with different protocols
Advanced tools for NAT-PAT analysis and calculations
Calculate available ports for PAT based on network requirements
Estimate NAT performance metrics based on configuration
How NAT/PAT differs from other networking concepts
Practical examples with solutions to understand NAT-PAT concepts
Trace the NAT translation process when a private host (192.168.1.100) accesses a public server (203.0.113.1).
Original Packet: Src=192.168.1.100:12345, Dst=203.0.113.1:80
After NAT: Src=203.0.113.10:12345, Dst=203.0.113.1:80
Return Packet: Src=203.0.113.1:80, Dst=203.0.113.10:12345
After Reverse NAT: Src=203.0.113.1:80, Dst=192.168.1.100:12345
The private host can communicate with the public server through NAT translation, with the NAT device maintaining a translation table entry for the session.
Configure PAT to allow 100 internal hosts to access the internet using a single public IP address.
!
interface GigabitEthernet0/0
description LAN Interface
ip address 192.168.1.1 255.255.255.0
ip nat inside
!
interface GigabitEthernet0/1
description WAN Interface
ip address 203.0.113.10 255.255.255.252
ip nat outside
!
access-list 1 permit 192.168.1.0 0.0.0.255
!
ip nat inside source list 1 interface GigabitEthernet0/1 overload
!Access List: Defines which internal addresses to translate
Interface Config: Marks inside/outside interfaces
Overload: Enables PAT (many-to-one translation)
Effect: All internal hosts share single public IP with unique ports
Internal hosts cannot reach external servers despite NAT configuration.
Step 1: Check interface configuration (inside/outside)
Step 2: Verify access lists allow traffic
Step 3: Check translation table for entries
Step 4: Verify routing to destination
Show NAT translations: show ip nat translations
Show NAT statistics: show ip nat statistics
Clear NAT table: clear ip nat translation *
Debug NAT: debug ip nat
Test your understanding of NAT-PAT concepts
Hover over the cards to learn more about key concepts
Address translation
Port translation
Mapping storage
Internal addresses
External addresses
Translation device
Network protection
Connection tracking