Network address translation (NAT) allows remapping of one IP address space to another. Types of NAT include static NAT, dynamic NAT, and port address translation (PAT). NAT provides benefits like IP address conservation, security, and flexibility. On Cisco routers, NAT operations follow an order of inside-to-outside and outside-to-inside translation. NAT can be deployed in scenarios involving MPLS VPNs, IP multicast, high availability, and application-level gateways. Configuration of NAT varies between Cisco routers and ASA firewalls.
This document provides an overview of Network Address Translation (NAT) including:
- Why NAT is used to connect networks with private IP addresses to the Internet and during network mergers.
- NAT implementation considerations such as advantages of address conservation and flexibility but disadvantages of delays and incompatible applications.
- Common NAT configurations like dynamic NAT, dynamic NAT with overloading, and static NAT.
How to configure static nat on cisco routersIT Tech
This document provides instructions for configuring static network address translation (NAT) on a Cisco router to map a private IP address to a public IP address. It explains that NAT allows private IP addresses on an internal network to be represented by public IP addresses on the external network. It then outlines the steps to configure static NAT on a Cisco router by defining the inside and outside interfaces, and using commands like "ip nat inside" and "ip nat outside" to identify the interfaces and "ip nat inside source static" to define the address mapping. It verifies the NAT configuration is working properly using show commands.
This document discusses Network Address Translation (NAT) and Port Address Translation (PAT). It defines key NAT terms and private IP address ranges. It then describes the main features of NAT and PAT, including static and dynamic NAT mappings and how PAT uses port numbers to map multiple private IPs to a single public IP. The document provides examples for configuring static NAT, dynamic NAT, and PAT. It also discusses troubleshooting NAT and changing dynamic NAT configurations.
NAT (network address translation) & PAT (port address translation)Netwax Lab
NAT (Network Address Translation) allows private IP networks to connect to the Internet by translating private IP addresses to public IP addresses. It operates on a router, connecting internal and external networks. NAT provides security by hiding internal network addresses and conserving IP addresses. There are various NAT types, including static NAT for one-to-one address mapping, dynamic NAT for mapping private addresses to public addresses from a pool, and NAT overload/PAT for mapping multiple private addresses to a single public address using ports.
This document describes network address translation (NAT) and different NAT types. It includes a course on Cisco CCNA about NAT taught at Tehran Institute of Technology. The course covers introduction to NAT and private vs public addresses. It then describes static NAT, dynamic NAT, and port address translation. The document provides examples of configuring static and dynamic NAT on routers to allow internal hosts to access the internet using public IP addresses.
NAT is used to translate private IP addresses to public IP addresses to allow access to the internet. There are different types of NAT including static NAT for one-to-one mapping, dynamic NAT for mapping multiple private addresses to public addresses from a pool, and NAT overload/PAT which maps multiple private addresses to a single public address using port addressing. The document provides configuration examples for static, dynamic, and overload NAT on a Cisco router.
- IPv4 addresses will be exhausted within 1000 days, so IPv6 adoption is urgently needed
- Getting IPv6 addresses from your LIR and setting up basic routing is straightforward using existing IPv4 knowledge and tools
- A sample IPv6 network deployment plan is outlined, including addressing schemes, interface configuration, routing protocols, and DNS/reverse DNS setup
This document provides an overview of Network Address Translation (NAT) including:
- Why NAT is used to connect networks with private IP addresses to the Internet and during network mergers.
- NAT implementation considerations such as advantages of address conservation and flexibility but disadvantages of delays and incompatible applications.
- Common NAT configurations like dynamic NAT, dynamic NAT with overloading, and static NAT.
How to configure static nat on cisco routersIT Tech
This document provides instructions for configuring static network address translation (NAT) on a Cisco router to map a private IP address to a public IP address. It explains that NAT allows private IP addresses on an internal network to be represented by public IP addresses on the external network. It then outlines the steps to configure static NAT on a Cisco router by defining the inside and outside interfaces, and using commands like "ip nat inside" and "ip nat outside" to identify the interfaces and "ip nat inside source static" to define the address mapping. It verifies the NAT configuration is working properly using show commands.
This document discusses Network Address Translation (NAT) and Port Address Translation (PAT). It defines key NAT terms and private IP address ranges. It then describes the main features of NAT and PAT, including static and dynamic NAT mappings and how PAT uses port numbers to map multiple private IPs to a single public IP. The document provides examples for configuring static NAT, dynamic NAT, and PAT. It also discusses troubleshooting NAT and changing dynamic NAT configurations.
NAT (network address translation) & PAT (port address translation)Netwax Lab
NAT (Network Address Translation) allows private IP networks to connect to the Internet by translating private IP addresses to public IP addresses. It operates on a router, connecting internal and external networks. NAT provides security by hiding internal network addresses and conserving IP addresses. There are various NAT types, including static NAT for one-to-one address mapping, dynamic NAT for mapping private addresses to public addresses from a pool, and NAT overload/PAT for mapping multiple private addresses to a single public address using ports.
This document describes network address translation (NAT) and different NAT types. It includes a course on Cisco CCNA about NAT taught at Tehran Institute of Technology. The course covers introduction to NAT and private vs public addresses. It then describes static NAT, dynamic NAT, and port address translation. The document provides examples of configuring static and dynamic NAT on routers to allow internal hosts to access the internet using public IP addresses.
NAT is used to translate private IP addresses to public IP addresses to allow access to the internet. There are different types of NAT including static NAT for one-to-one mapping, dynamic NAT for mapping multiple private addresses to public addresses from a pool, and NAT overload/PAT which maps multiple private addresses to a single public address using port addressing. The document provides configuration examples for static, dynamic, and overload NAT on a Cisco router.
- IPv4 addresses will be exhausted within 1000 days, so IPv6 adoption is urgently needed
- Getting IPv6 addresses from your LIR and setting up basic routing is straightforward using existing IPv4 knowledge and tools
- A sample IPv6 network deployment plan is outlined, including addressing schemes, interface configuration, routing protocols, and DNS/reverse DNS setup
This document provides an overview of IPv6 basics including:
- The need for IPv6 due to the depletion of IPv4 addresses with the rise of Internet of Things devices.
- IPv6 uses a 128-bit address format composed of 8 groups of 4 hexadecimal digits separated by colons.
- IPv6 addresses are categorized into different types including link-local, unique local, and global unicast addresses.
- IPv6 uses prefix lengths like CIDR notation to represent prefixes and subnets are based on dividing the 64-bit prefix.
- IPv6 addresses can be auto-configured using EUI-64 or randomly generated interface IDs, and DHCPv6 can assign addresses and options.
This document outlines an IPv6 lab and techtorial that covers IPv6 addressing, neighbor discovery, static routing, OSPFv3, BGP, and tunneling. The agenda includes lectures on these topics as well as corresponding labs to provide hands-on experience. Prerequisites for the session are basic network engineering knowledge and interest in Cisco technologies. The document then goes on to describe IPv6 addressing formats, types of addresses, and how addresses are allocated to interfaces.
This document discusses various techniques for allowing peer-to-peer communication between hosts located behind Network Address Translation (NAT) devices, including NAT traversal using UDP hole punching, TCP hole punching, relaying, connection reversal, and the TURN protocol. It also covers proxy protocols like SOCKS that can be used to traverse NATs, as well as the UPnP standard for automatic port forwarding configuration.
Network Address Translation (NAT) allows private IP networks to connect to the public Internet using a single public IP address. NAT is run on routers and works by replacing the private IP addresses and port numbers in data packets with public IP addresses and port numbers when the packets leave the private network, and translating them back when packets return. This conserves public IP addresses and allows private networks to use non-routable address ranges while still accessing the Internet. Common NAT configurations include one-to-one mapping of addresses, IP masquerading of multiple private addresses to a single public address, and load balancing multiple servers accessed through a single public IP.
This document discusses network address translation (NAT) and how it allows private IP addresses on a local network to connect to public IP addresses on the internet. It explains that NAT involves translating IP addresses and ports so that a private network can be represented by a single public IP address from the perspective of the internet. It also describes different types of NAT, such as basic NAT, port address translation, source NAT, and destination NAT. Specific scenarios like browsing the web, port forwarding, and issues with certain protocols like FTP are also covered at a high level.
This document provides an overview of IPv6 including:
- The expanded 128-bit addressing scheme and different address types like unicast, multicast, etc.
- Simplified header format compared to IPv4 and removal of checksumming at the network layer.
- Transition mechanisms between IPv4 and IPv6 like 6to4 and ISATAP addressing.
- Hierarchical and aggregatable global address allocation policies and interface identifier assignments.
- IPv6 header options and their processing model compared to IPv4.
This document provides an overview of IPv6 addressing and connectivity. It describes the various types of IPv6 addresses including global aggregateable unicast addresses, site-local addresses, unique local addresses, and link-local addresses. It also covers IPv6 address formats and special addresses like the unspecified, loopback, multicast, and solicited node multicast addresses. Transition mechanisms from IPv4 to IPv6 are also briefly mentioned.
The “Hands on Experience with IPv6 Routing and Services” Techtorial will provide attendees an opportunity to configure, troubleshoot, design and implement an IPv6 network using IPv6 technologies and features such as: IPv6 addressing, IPv6 neighbor discovery, HSRPv6, static routing, OSPFv3, EIGRPv6 and BGPv6. You will be provided with a scenario made up of an IPv4 network where you will get the opportunity to configure and implement IPv6 based on the requirements on the network, i.e., where would you deploy dual stack, where it make sense to do funneling and how to deploy IPv6 routing protocols without impacting your existing Network infrastructure.
IPv6 Autoconfig full process from initial configuration of IPV6 Node. Refreshment of IPv6 Addresses using RA or DHCPv6. How to keep your home config everywhere you go and only logout when you want to, not when you move to a new access point.
IPv6 is the next generation Internet Protocol that provides a vastly larger number of IP addresses compared to the current IPv4. It features 128-bit addressing which allows for trillions of devices to have unique IP addresses. IPv6 also aims to make networking more secure and allow for more efficient routing. The transition from IPv4 to IPv6 is underway, with most modern operating systems and network hardware now supporting IPv6, though applications support is still growing. IPv6's expanded addressing capabilities and additional features will help meet future demands on the Internet as more devices connect online.
Network Address Translation (NAT) allows a single device like a router to act as an agent between a private network and the public internet using a single public IP address. This conserves limited public IP addresses as only the NAT device needs a public IP, while an entire private network can use private IP addresses. NAT works by translating the private IP address and port of devices in the private network to the public IP address and unique port of the NAT device when communicating with the public internet, and vice versa for incoming traffic. This allows all private network devices to access the internet through the single public IP address of the NAT device.
This document provides an introduction to IPv6, including an overview of its key features and differences from IPv4. It discusses how IPv6 was developed to address the exhaustion of IPv4 address space and larger routing tables. The core features covered are the new IPv6 header format, its large 128-bit address space, stateless and stateful address configuration, built-in security via IPsec, and improved support for areas like quality of service and network interactions through protocols like Neighbor Discovery.
The document discusses IPv6 addressing and summarizes:
- IPv6 addresses are 128-bit hexadecimal addresses consisting of 8 sections separated by colons, with the first 3 sections making up the prefix or network portion and the last 4 sections being the interface ID.
- Addressing hierarchies are defined, with the first bits identifying the registry and subsequent bits identifying the ISP and site.
- Methods for compressing zeros, representing loopback addresses, and defining link-local and multicast addresses are covered.
- IPv6 enhances IPv4 by allowing larger addresses and more efficient routing while introducing features like built-in encryption.
Network address translation (NAT) is a method of remapping one IP address space into another by modifying network address information in Internet Protocol (IP) datagram packet headers while they are in transit across a traffic routing device.
This document provides an overview of IPv6 including:
- The history and motivations for developing IPv6 due to IPv4 address exhaustion.
- An introduction to IPv6 addressing and prefixes.
- Transition technologies like tunnels to help with gradual IPv6 deployment.
- IPv6 control protocols for tasks like neighbor discovery and routing.
- Details on how IPv6 addresses are represented textually and allocated.
The document discusses IPv6 Neighbor Discovery. It explains that Neighbor Discovery allows nodes on the same link to discover each other, determine link-layer addresses, find routers, and maintain reachability information for active neighbors. It describes the various Neighbor Discovery message types and processes, including address resolution, duplicate address detection, and redirect function. Conceptual data structures for neighbor caches, destination caches, prefix lists, and default router lists are also outlined.
Internet Protocol version 6 (IPv6) is what you are going to discover onwards. Here, you will get format, features and related required information of IPv6 addresses and its related protocols.
IPv6 is the most recent version of the Internet Protocol. It features a 128-bit address space, compared to 32 bits in IPv4, allowing for many more IP addresses. IPv6 also includes features like stateless autoconfiguration of hosts, plug and play capability, built-in IP security, and mobility. Transition mechanisms like dual stacking, tunneling, and translation are needed for IPv6 hosts to communicate with IPv4 networks during the transition period. Most modern operating systems and applications now support IPv6.
You may have hoped to retire before IPv6 became a reality, but unfortunately the IPv4 address exhaustion came too fast. For the rest of us, we’re going to bite off a small piece of the 15-year old IPv6 pie and talk about how to get started!
• Address format refresher
• IPv4 and IPv6 protocol comparison
• IPv6 neighbor discovery and auto-configuration
• Current migration and coexistence strategies
• ICMPv6, DHCPv6, and DNSv6
• How to get started at home
Network Address Translation (NAT) allows devices on a private network to use public IP addresses to access the Internet. NAT translates private IP addresses to public IP addresses to conserve the limited number of public addresses. There are three main types of NAT: static NAT assigns a public IP to a device; dynamic NAT uses a pool of public IPs; and port address translation uses ports of a single public IP for multiple private devices. NAT provides advantages like acting as a firewall and allowing unlimited private devices to share a single public IP. However, it also causes some applications to work less effectively and complicates troubleshooting when IP addresses change.
The document discusses the issues with Network Address Translation (NAT) and why the author cares about IPv6. It summarizes the key impacts of NAT, including that it prevents devices on the same network from acting as peers, relies on external hosts or relays, and is vulnerable to denial of service attacks and loss of state. The author argues that this goes against the intended peer-to-peer nature of the Internet protocols and that IPv6 removes the fundamental constraints of NAT by allowing nodes to use their own IP addresses and communicate directly.
This document provides an overview of IPv6 basics including:
- The need for IPv6 due to the depletion of IPv4 addresses with the rise of Internet of Things devices.
- IPv6 uses a 128-bit address format composed of 8 groups of 4 hexadecimal digits separated by colons.
- IPv6 addresses are categorized into different types including link-local, unique local, and global unicast addresses.
- IPv6 uses prefix lengths like CIDR notation to represent prefixes and subnets are based on dividing the 64-bit prefix.
- IPv6 addresses can be auto-configured using EUI-64 or randomly generated interface IDs, and DHCPv6 can assign addresses and options.
This document outlines an IPv6 lab and techtorial that covers IPv6 addressing, neighbor discovery, static routing, OSPFv3, BGP, and tunneling. The agenda includes lectures on these topics as well as corresponding labs to provide hands-on experience. Prerequisites for the session are basic network engineering knowledge and interest in Cisco technologies. The document then goes on to describe IPv6 addressing formats, types of addresses, and how addresses are allocated to interfaces.
This document discusses various techniques for allowing peer-to-peer communication between hosts located behind Network Address Translation (NAT) devices, including NAT traversal using UDP hole punching, TCP hole punching, relaying, connection reversal, and the TURN protocol. It also covers proxy protocols like SOCKS that can be used to traverse NATs, as well as the UPnP standard for automatic port forwarding configuration.
Network Address Translation (NAT) allows private IP networks to connect to the public Internet using a single public IP address. NAT is run on routers and works by replacing the private IP addresses and port numbers in data packets with public IP addresses and port numbers when the packets leave the private network, and translating them back when packets return. This conserves public IP addresses and allows private networks to use non-routable address ranges while still accessing the Internet. Common NAT configurations include one-to-one mapping of addresses, IP masquerading of multiple private addresses to a single public address, and load balancing multiple servers accessed through a single public IP.
This document discusses network address translation (NAT) and how it allows private IP addresses on a local network to connect to public IP addresses on the internet. It explains that NAT involves translating IP addresses and ports so that a private network can be represented by a single public IP address from the perspective of the internet. It also describes different types of NAT, such as basic NAT, port address translation, source NAT, and destination NAT. Specific scenarios like browsing the web, port forwarding, and issues with certain protocols like FTP are also covered at a high level.
This document provides an overview of IPv6 including:
- The expanded 128-bit addressing scheme and different address types like unicast, multicast, etc.
- Simplified header format compared to IPv4 and removal of checksumming at the network layer.
- Transition mechanisms between IPv4 and IPv6 like 6to4 and ISATAP addressing.
- Hierarchical and aggregatable global address allocation policies and interface identifier assignments.
- IPv6 header options and their processing model compared to IPv4.
This document provides an overview of IPv6 addressing and connectivity. It describes the various types of IPv6 addresses including global aggregateable unicast addresses, site-local addresses, unique local addresses, and link-local addresses. It also covers IPv6 address formats and special addresses like the unspecified, loopback, multicast, and solicited node multicast addresses. Transition mechanisms from IPv4 to IPv6 are also briefly mentioned.
The “Hands on Experience with IPv6 Routing and Services” Techtorial will provide attendees an opportunity to configure, troubleshoot, design and implement an IPv6 network using IPv6 technologies and features such as: IPv6 addressing, IPv6 neighbor discovery, HSRPv6, static routing, OSPFv3, EIGRPv6 and BGPv6. You will be provided with a scenario made up of an IPv4 network where you will get the opportunity to configure and implement IPv6 based on the requirements on the network, i.e., where would you deploy dual stack, where it make sense to do funneling and how to deploy IPv6 routing protocols without impacting your existing Network infrastructure.
IPv6 Autoconfig full process from initial configuration of IPV6 Node. Refreshment of IPv6 Addresses using RA or DHCPv6. How to keep your home config everywhere you go and only logout when you want to, not when you move to a new access point.
IPv6 is the next generation Internet Protocol that provides a vastly larger number of IP addresses compared to the current IPv4. It features 128-bit addressing which allows for trillions of devices to have unique IP addresses. IPv6 also aims to make networking more secure and allow for more efficient routing. The transition from IPv4 to IPv6 is underway, with most modern operating systems and network hardware now supporting IPv6, though applications support is still growing. IPv6's expanded addressing capabilities and additional features will help meet future demands on the Internet as more devices connect online.
Network Address Translation (NAT) allows a single device like a router to act as an agent between a private network and the public internet using a single public IP address. This conserves limited public IP addresses as only the NAT device needs a public IP, while an entire private network can use private IP addresses. NAT works by translating the private IP address and port of devices in the private network to the public IP address and unique port of the NAT device when communicating with the public internet, and vice versa for incoming traffic. This allows all private network devices to access the internet through the single public IP address of the NAT device.
This document provides an introduction to IPv6, including an overview of its key features and differences from IPv4. It discusses how IPv6 was developed to address the exhaustion of IPv4 address space and larger routing tables. The core features covered are the new IPv6 header format, its large 128-bit address space, stateless and stateful address configuration, built-in security via IPsec, and improved support for areas like quality of service and network interactions through protocols like Neighbor Discovery.
The document discusses IPv6 addressing and summarizes:
- IPv6 addresses are 128-bit hexadecimal addresses consisting of 8 sections separated by colons, with the first 3 sections making up the prefix or network portion and the last 4 sections being the interface ID.
- Addressing hierarchies are defined, with the first bits identifying the registry and subsequent bits identifying the ISP and site.
- Methods for compressing zeros, representing loopback addresses, and defining link-local and multicast addresses are covered.
- IPv6 enhances IPv4 by allowing larger addresses and more efficient routing while introducing features like built-in encryption.
Network address translation (NAT) is a method of remapping one IP address space into another by modifying network address information in Internet Protocol (IP) datagram packet headers while they are in transit across a traffic routing device.
This document provides an overview of IPv6 including:
- The history and motivations for developing IPv6 due to IPv4 address exhaustion.
- An introduction to IPv6 addressing and prefixes.
- Transition technologies like tunnels to help with gradual IPv6 deployment.
- IPv6 control protocols for tasks like neighbor discovery and routing.
- Details on how IPv6 addresses are represented textually and allocated.
The document discusses IPv6 Neighbor Discovery. It explains that Neighbor Discovery allows nodes on the same link to discover each other, determine link-layer addresses, find routers, and maintain reachability information for active neighbors. It describes the various Neighbor Discovery message types and processes, including address resolution, duplicate address detection, and redirect function. Conceptual data structures for neighbor caches, destination caches, prefix lists, and default router lists are also outlined.
Internet Protocol version 6 (IPv6) is what you are going to discover onwards. Here, you will get format, features and related required information of IPv6 addresses and its related protocols.
IPv6 is the most recent version of the Internet Protocol. It features a 128-bit address space, compared to 32 bits in IPv4, allowing for many more IP addresses. IPv6 also includes features like stateless autoconfiguration of hosts, plug and play capability, built-in IP security, and mobility. Transition mechanisms like dual stacking, tunneling, and translation are needed for IPv6 hosts to communicate with IPv4 networks during the transition period. Most modern operating systems and applications now support IPv6.
You may have hoped to retire before IPv6 became a reality, but unfortunately the IPv4 address exhaustion came too fast. For the rest of us, we’re going to bite off a small piece of the 15-year old IPv6 pie and talk about how to get started!
• Address format refresher
• IPv4 and IPv6 protocol comparison
• IPv6 neighbor discovery and auto-configuration
• Current migration and coexistence strategies
• ICMPv6, DHCPv6, and DNSv6
• How to get started at home
Network Address Translation (NAT) allows devices on a private network to use public IP addresses to access the Internet. NAT translates private IP addresses to public IP addresses to conserve the limited number of public addresses. There are three main types of NAT: static NAT assigns a public IP to a device; dynamic NAT uses a pool of public IPs; and port address translation uses ports of a single public IP for multiple private devices. NAT provides advantages like acting as a firewall and allowing unlimited private devices to share a single public IP. However, it also causes some applications to work less effectively and complicates troubleshooting when IP addresses change.
The document discusses the issues with Network Address Translation (NAT) and why the author cares about IPv6. It summarizes the key impacts of NAT, including that it prevents devices on the same network from acting as peers, relies on external hosts or relays, and is vulnerable to denial of service attacks and loss of state. The author argues that this goes against the intended peer-to-peer nature of the Internet protocols and that IPv6 removes the fundamental constraints of NAT by allowing nodes to use their own IP addresses and communicate directly.
This document provides an introduction to Network Address Translation (NAT) and describes a simple simulation configured to allow hosts from a private network to access a server through its public IP address. NAT is designed to separate private IP addresses from public IP addresses. The simulation involves configuring two routers, with one router using static NAT with Port Address Translation (PAT) to allow a server to be accessed via its public IP, and the other router using dynamic NAT and PAT to allow multiple private IPs to access the network. This demonstrates how NAT can translate private network addresses to access resources externally using public IP addresses.
The document outlines an agenda for a 3HOWs event discussing IPv6 and MPLS technology. The morning sessions will cover how to deal with IPv6, including why it is important now due to limited IPv4 addresses, IPv6 addressing details, and how to connect to IPv6. The afternoon will discuss how to connect with MPLS technology, the benefits it provides for interconnecting offices, and actual customer case studies. Questions from attendees will conclude the event.
CCNA stands for Cisco Certified Network Associate. Routers are networking devices that direct data packets to their destination. Routers use routing protocols like RIP to share information and determine the best paths between networks. Access control lists (ACLs) allow routers to filter traffic and restrict access to networks for security purposes. Network Address Translation (NAT) allows multiple devices to share public IP addresses to communicate on the Internet.
The document discusses the upcoming introduction of IPv6. [1] IPv6 is a new standard for IP numbering that will provide more IP addresses as the current IPv4 addresses are running out. [2] It will help overcome limitations in the old IPv4 system and ensure there are enough addresses available into the next century. [3] The document outlines some of the key features and improvements IPv6 will provide, such as larger packet sizes, better security features, quality of service support, and mobility support.
This document discusses the Teredo protocol, which enables IPv6 connectivity for nodes located behind IPv4 NAT devices. It explains how Teredo works by tunneling IPv6 packets over UDP through NATs. While Teredo allows IPv6 connectivity, it also raises security concerns by bypassing security controls and allowing unsolicited traffic. The document analyzes attacks that could exploit vulnerabilities in Teredo tunnels, such as a denial of service attack against a Teredo server using a single packet. It investigates whether Teredo represents a security risk or is a worthwhile transition mechanism from IPv4 to IPv6.
This document provides an overview and agenda for a course on Introduction to IPv6 for Service Providers. The course covers IPv6 essentials such as addressing, operations, applications/services, routing protocols, and transition strategies. It discusses the rationale for adopting IPv6 including the depletion of IPv4 addresses and the need to support the growing number of internet-connected devices. The document outlines some of the key limitations of IPv4 like fragmentation and the issues with long-term reliance on Network Address Translation (NAT) to overcome the address space depletion.
This document proposes using Locator/ID Separation Protocol (LISP) to simplify routing in networks that use IPsec VPN devices (IVDs). LISP separates endpoint identifiers from routing locators, allowing more efficient routing between secure routers connected via IVDs without needing full-mesh generic routing encapsulation (GRE) tunnels. LISP uses IP/UDP encapsulation that works seamlessly over IVDs, and limits the number of IP prefixes IVDs must store to simplify operations. The document compares LISP to the current GRE tunnel approach and outlines how LISP's separation of identifiers and locators can improve routing scalability and mobility in IVD networks.
This document provides an overview of Network Address Translation (NAT) for IPv4. It contains the following sections:
1. NAT Operation - Explains the purpose and function of NAT, the different types of NAT (static, dynamic, PAT), and the advantages and disadvantages of NAT.
2. Configure NAT - Details how to configure static NAT, dynamic NAT, PAT, and port forwarding on Cisco routers using the command line interface.
3. Troubleshoot NAT - Covers how to troubleshoot NAT issues in a network.
The document is intended to instruct users on the basic concepts and configuration of NAT to provide IPv4 address translation and scalability in small to medium business networks.
MikroTik is a Linux-based router that can be installed and fully operated on a regular PC. It has many features, including performing functions like NAT, bandwidth management, and filtering at the 3-layer network level, allowing it to efficiently route high bandwidth and perform operations like NAT and filtering on low-end hardware. MikroTik also offers stability, security, and ease of configuration through its web interface and command line tools.
NAT maps private IP addresses to public IP addresses, allowing multiple devices on a private network to share a single public IP address to access the Internet. It is commonly used when there is a shortage of IPv4 addresses. There are different types of NAT, including dynamic NAT which maps private addresses to public addresses on a need basis, and NAPT which allows thousands of devices to share one IP address by also mapping port numbers. NAT solves issues like merging networks with duplicate private addresses and changing ISPs without renumbering an entire network.
Using a set of Network Critical Success Factors (NCSFs) - things network operators need to get right to run a good network - I then use them to evaluate IPv4 Network Address Translation.
I then look at the fundamental nature of IPv6 (and IPv4), and how it can better suite the two different application communications architectures - client-server and peer-to-peer.
Finally, I describe how some of the perceived benefits of NAT can be achieved with IPv6 without performing address translation.
This is an updated version of my AusNOG 2016 presentation on the same topic.
This document provides a 3-paragraph summary of a 10-page project report on IPv6. The report was submitted by Udipto Ghosh to MIT Pune in partial fulfillment of a post-graduate diploma in management. The summary discusses that IPv6 is an evolutionary upgrade to IPv4 designed to allow continued growth of the internet. It also describes some key features of IPv6 like larger address space and auto-configuration. The transition from IPv4 to IPv6 is expected to occur gradually as IPv6 is deployed incrementally for early benefits while coexisting with IPv4 for a long time.
This document discusses setting up a redundant LAN network. It describes what a LAN network is and the importance of network redundancy. It then provides details on various methods for implementing redundancy, including creating VPNs, using redundancy protocols like HSRP and VRRP, basic routing, MPLS routing, access lists, NAT/PAT, and configuring redundant LAN connections. The document includes configuration examples and concludes that the project was a valuable learning experience for understanding real-world networking operations.
Now more than ever, today’s businesses require reliable network connectivity and access to corporate resources. Connections to and from business units, vendors and SOHOs are all equally important to keep the continuity when needed. Business runs all day, every day and even in off hours. Most companies run operations around the clock, seven days a week so it’s important to realize that to keep a solid business continuity strategy, redundancy technologies should be considered and/or implemented.
So, we need to keep things up and available all the time. This is sometimes referred to five nines (99.999) uptime. The small percentage of downtime is accounted for unforeseen incidents, or ‘scheduled maintenance’ and usually set to take place during times of least impact, like in the middle of the night, or on holiday weekends if planned. If this is not a part of your systems and network architecture it should be considered if you want to keep a high level of availability. Because things break and unforeseen events do take place, we need to evaluate the need for creating an architecture that is ‘highly available’, or up as much as possible, with failures foreseen ahead of time and the only downtime, is to do planned maintenance.
Solving QoS multicast routing problem using aco algorithm Abdullaziz Tagawy
In IP multicasting messages are sent from the source node to all destination nodes. In order to meet QoS requirements an optimizing algorithm is needed. We propose an Ant Colony Optimization algorithm to do so. Ants release a chemical called pheromone while searching for food. They are capable of finding shortest path to their target. This can give an effective optimal solution to our Multicast Routing Problem.
The document discusses DHCP, NAT, and forwarding of IP packets. It begins by explaining DHCP and how DHCP servers dynamically assign IP addresses and network configuration parameters to devices on a network. It then covers network address translation, how NAT allows private IP addresses to be mapped to public IP addresses. The document concludes by discussing how routers forward IP packets based on the destination address, and methods for routing tables and longest prefix matching to determine the appropriate path for packet forwarding.
NAT maps private IP addresses to public IP addresses, allowing multiple devices on a private network to share a single public IP address to access the Internet. It is commonly used to conserve public IP addresses and avoid renumbering networks when changing ISPs. There are different types of NAT including static NAT, dynamic NAT, and NAPT, each with different mapping behaviors between private and public addresses.
This presentation summarizes the Cisco Certified Network Associate (CCNA) certification and covers networking concepts relevant to the CCNA including networking devices, the OSI model, IP addressing, routing, access lists, network address translation, switches, virtual LANs, WAN connection types, wireless technology, and comparisons of 802.11 wireless standards.
The CSC SSM runs Content Security and Control software on some ASA models to provide protection against viruses, spyware, spam, and other unwanted traffic. It can scan FTP, HTTP/HTTPS, POP3, and SMTP traffic on their standard ports. You must obtain configuration information like the IP addresses and passwords to set up traffic scanning between the ASA and CSC SSM. The document provides steps to create access lists and policy maps to divert specified traffic to the CSC SSM for scanning.
The document discusses various TCP inspection policies that can be set on an ASA firewall to control and inspect TCP connections and traffic. These policies include limiting the number of simultaneous and partially opened TCP connections, setting timeout durations for idle, half-closed and embryonic connections, decrementing TTL values, using random sequence numbers, and verifying TCP properties like retransmissions, checksums, ACK flags, and sequence numbers within windows. The policies are implemented using class-maps, policy-maps and applying the policies to interfaces.
The document discusses configuring an ASA firewall to inspect HTTP traffic and block various threats such as URL redirection, Java applets, ActiveX controls, .exe file extensions, blocked sites by host, non-English languages, compression methods other than zip/rar, and HTTPS sites using DNS inspection. It also covers inspecting HTTP on non-standard ports, blocking Hotmail attachments, torrent traffic, and using FQDN objects to block domains.
Virtual Switching System (VSS) allows two physical switches to be combined into one logical switch, eliminating spanning tree blocking and increasing bandwidth. Key aspects of VSS include the virtual switch link (VSL) that carries control traffic, protocols like LMP and RRP that manage the VSL and determine the active and standby roles, and stateful switchover (SSO) for redundancy. VSS provides a loop-free topology to spanning tree and acts as a single logical node, simplifying management and recovery from failures.
vPC allows links connected to two Nexus switches to appear as a single port channel to a third device. It provides advantages like eliminating STP blocked ports, using all available uplink bandwidth, and fast convergence upon failures. Configuring vPC involves the vPC peer switches, peer link, domain, and member ports. vPC avoids loops at the data plane layer. It can be used within a single data center for active-active server connectivity or between two data centers to extend VLANs across sites at layer 2. Object tracking allows vPC to modify its state based on peer link states.
IPSec VPN is used to securely connect sites over the internet by forming an encrypted tunnel between peers. It uses the IPSec protocol suite including ESP and AH to provide data confidentiality, integrity, and authentication. IKE negotiates IPSec security associations and keys using either IKEv1 or IKEv2. NAT traversal (NAT-T) allows IPSec to work through NAT devices by encapsulating packets in UDP port 4500. Phase 1 of IKE establishes an IKE security association to protect further negotiation, while Phase 2 establishes IPSec security associations to encrypt data traffic.
1. NAT/PAT Explained
Content
NAT/PAT Explained on Cisco Router
o What do you mean by NAT/PAT
Types of NAT
Static NAT
Dynamic NAT
Static PAT
Advantages of using NAT/PAT
IPv4 Address Conservation
Security
Flexibility
Order of Operation Cisco Router
Inside-to-Outside
Outside-to-Inside
What is DNAT
What is SNAT
Terminology Used
Inside Local
Inside Global
Outside Local
Outside Global
o NAT Deployment Scenario
NAT Virtual Interface or NVI
NAT on a stick or hair-pinning
NAT with MPLS VPN or VRF-Aware NAT
NAT with IP Multicast
NAT Box-to-Box High-Availability or SNAT
NAT using Application Layer Gateways (ALG)
NAT Port Translation (NAT-PT)
NAT in Overlapping Networks
NAT for TCP Load Distribution
NAT with HSRP
NAT using Route Map
NAT with IPSec VPN
NAT with Rotary
NAT/PAT on Cisco ASA
o NAT in Routed Mode
o NAT in transparent Mode
2. o NAT with Context Mode - Shared Interface using NAT
o Difference between NAT on 8.2 and 8.3 +
Upgrade from 8.2 to 8.4
o NAT Order of Operation on 8.2 and 8.3 +
o What is Network Object NAT
o What is Twice NAT
o Types of NAT
NAT Control
NAT Exemptions
Configuration on 8.2
Configuration on 8.4
Identity NAT
Configuration on 8.2
Configuration on 8.4
Static NAT
Configuration on 8.2
Configuration on 8.4
Static PAT
Configuration on 8.2
Configuration on 8.4
Dynamic NAT
Configuration on 8.2
Configuration on 8.4
Dynamic PAT
Configuration on 8.2
Configuration on 8.4
Dynamic Policy NAT
Configuration on 8.2
Configuration on 8.4
o Troubleshooting NAT on ASA
NAT/PAT on Nexus Switches
o NAT support on Nexus Switches
o ITD support for SLB NAT on Nexus Switches
o Configuration on Nexus Switches for NAT Support
3. NAT/PAT Explained on Router
What do you mean by NAT/PAT
Network address translation (NAT) is a methodology of remapping one IP address space into another by
modifying network address information in Internet Protocol (IP) datagram packet headers while they are
in transit across a traffic routing device. PAT translates multiple real addresses to a single mapped IP
address by translating the real address and source port to the mapped address and a unique port
Types of NAT
Static NAT
Static address translation (static NAT)—Allows one-to-one mapping between local and global addresses.
It is bi-directional in nature, means both the IPs can initiate the traffic.
For static inside NAT, routing is first checked and then only the packet is translated.
For static outside NAT, translation is first done and then the routing is checked
Dynamic NAT
Dynamic NAT translates a group of real addresses to a pool of mapped addresses that are routable on
the destination network. The mapped pool may include fewer addresses than the real group. With
dynamic NAT, translations do not exist in the NAT table until the router receives traffic that requires
translation. Dynamic translations have a timeout period after which they are purged from the
translation table.
PAT or Port Address translation
PAT (or overloading) is a feature of Cisco IOS NAT that is used to translate internal (inside local) private
addresses to one or more outside (inside global, usually registered) IP addresses. Unique source port
numbers on each translation are used to distinguish between the conversations. PAT assigns a unique
source port for each UDP or TCP session. If available, the real source port number is used for the
mapped port. However, if the real port is not available, by default the mapped ports are chosen from
the same range of ports as the real port number: 0 to 511, 512 to 1023, and 1024 to 65535. Therefore,
ports below 1024 have only a small PAT pool that can be used.
4. Advantages of using NAT/PAT
IP address conservation - Saving depleting public IPv4 address
Security Purpose - Inside IP address is always hidden from the outside world.
Flexibility – It brings in a lot of flexibility to the environment while assigning address scheme
Order of Operation on Cisco Router –
http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/6209-5.html
Inside-to-Outside Outside-to-Inside
If IPSec then check input access list If IPSec then check input access list
Decryption - for CET or IPSec Decryption - for CET or IPSec
Check input access list Check input access list
Check input rate limits Check input rate limits
Input accounting Input accounting
Redirect to web cache Redirect to web cache
Policy routing NAT outside to inside (global to local translation)
Routing Policy routing
NAT inside to outside (local to global translation) Routing
Crypto (check map and mark for encryption) Crypto (check map and mark for encryption)
Check output access list Check output access list
Inspect (Context-based Access Control (CBAC)) Inspect CBAC
TCP intercept TCP intercept
Encryption Encryption
Queueing Queueing
What is DNAT
Destination network address translation (DNAT) is a technique for transparently changing the
destination IP address of an end route packet and performing the inverse function for any replies. Any
router situated between two endpoints can perform this transformation of the packet. DNAT is
commonly used to publish a service located in a private network on a publicly accessible IP address. This
use of DNAT is also called port forwarding, or DMZ when used on an entire server, which becomes
exposed to the WAN, becoming analogous to an undefended military demilitarized zone (DMZ).
What is SNAT
Stateful NAT (SNAT) allows two or more network address translators to function as a translation group.
One member of the translation group handles traffic requiring translation of IP address information.
Additionally, it informs the backup translator of active flows as they occur.
5. Terminology used
Inside Local – Configured IP address assigned to a host on the inside network.
Inside Global – The IP address of an inside host as it appears to the outside network, "Translated IP
Address".
Outside Global – The IP address of an outside host as it appears to the inside network.
Outside Local – The configured IP address assigned to a host in the outside network.
NAT Deployment Scenarios
NAT Virtual Interface or NVI
With the introduction of this new feature, called as NAT Virtual Interface (NVI) we can get rid of legacy
"inside" and "outside" commands. We don't need to configure static route for "ip nat inside source"
command. Instead we just enable nat on the interface and make it NVI.
More on this - http://blog.ine.com/2008/02/15/the-inside-and-outside-of-nat/
NAT on a stick or NAT Hair-pinning
What do we mean by Network Address Translation (NAT) on a stick? The term "on a stick" usually
implies the use of a single physical interface of a router for a task. Just as we can use sub interfaces of
the same physical interface to perform Inter-Switch Link (ISL) trunking, we can use a single physical
interface on a router in order to accomplish NAT. The need for NAT on a stick is rare.
Example - Nat on a stick is basically used when you usually have only one physical interface on the
router and you have a requirement to perform nat translation say on your internal network.
More on this - https://networklessons.com/network-services/cisco-ios-nat-stick-configuration-example/
6. NAT with MPLS VPNs or VRF aware NAT
Network Address Translation (NAT) Integration with MPLS VPNs feature allows multiple Multiprotocol
Label Switching (MPLS) Virtual Private Networks (VPNs) to be configured on a single device to work
together. NAT can differentiate which MPLS VPN it receives IP traffic from even if the MPLS VPNs are all
using the same IP addressing scheme. This enhancement enables multiple MPLS VPN customers to share
services while ensuring that each MPLS VPN is completely separate from the other. MPLS service
providers would like to provide value-added services such as Internet connectivity, domain name servers
(DNS), and voice over IP (VoIP) service to their customers. The providers require that their customers; IP
addresses be different when reaching the services. Because MPLS VPN allows customers to use
overlapped IP addresses in their networks, NAT must be implemented to make the services possible.
The Match-in-VRF Support for NAT feature extends VRF-aware NAT by supporting intra-VPN NAT
capability. In the intra-VPN NAT, both the local and global address spaces for end hosts are isolated to
their respective VPNs, and as a result translated addresses for hosts overlap each other. To separate the
address space for translated addresses among VPNs, configure the match-in-vrf keyword in the NAT
mapping (ip nat inside source command) configuration. Both static and dynamic NAT configurations
support the match-in-vrf keyword.
Example - Consider you are an ISP and providing various services to different customers. Two of your
customers are using same internal network range (i.e. 192.168.10.0/24) and are in different VRF.
Everything is fine, but there is request for both of these to access a shared service provided by ISP. How
will you keep both the Customers different while accessing shared services? The solution is to use NAT
with MPLS VPN's, so that while accessing the shared service both use NATted IP.
More on this - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/12-4/nat-
12-4-book/iadnat-mpls-vpn.html
NAT with IP Multicast
The IP Multicast Dynamic Network Address Translation (NAT) feature supports the source address
translation of multicast packets. You can use source address translation when you want to connect to
the Internet, but not all your hosts have globally unique IP addresses. NAT translates the internal local
addresses to globally unique IP addresses before sending packets to the outside network. The IP
multicast dynamic translation establishes a one-to-one mapping between an inside local address and
one of the addresses from the pool of outside global addresses.
Example - When a user (Source - 192.168.10.1) wants to send a multicast traffic over the internet. The
NATting device in the middle will change the source address 192.168.10.1 to a public IP (For example -
224.1.1.10) given in the pool, destination will remain the same.
7. More on this - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-2/nat-
xe-2-book/iadnat-multicast-dynamic.html
NAT Box-to-Box High-Availability or SNAT
SNAT involves two or more routers performing the NAT function as a group. These NAT routers
exchange information in their NAT translation databases with each other. Whenever a new NAT
connection occurs via one of the NAT routers, the router relays that information to the others in the
SNAT group. But these routers aren't just exchanging the IP addresses of the NAT IP flows; they're also
exchanging the TCP state of those flows. The standby routers have already created the NAT translation
table and are waiting for a failure on the active router. Only sessions that are already statically defined
receive the benefit of redundancy without the need for this feature. In the absence of SNAT, sessions
that use dynamic NAT mappings would be severed in the event of a critical failure and would have to be
reestablished.
Note - Cisco announces the end-of-sale and end-of life dates for the Cisco IOS Stateful Failover of
Network Address Translation (SNAT). The recommended replacement for the Cisco IOS SNAT feature is
the Cisco ASA Adaptive Security Appliance beginning with release 7.0.
Example – You have high availability configured between two routers and you want NAT information to
propagate to standby device in case the primary device fails
More on this - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/15-
mt/nat-15-mt-book/iadnat-b2b-ha.html
NAT using Application Layer Gateways (ALG)
NAT performs translation services on any TCP/UDP traffic that does not carry source and destination IP
addresses in the application data stream. Protocols that do not carry the source and destination IP
addresses include HTTP, TFTP, telnet, archive, finger, Network Time Protocol (NTP), Network File System
(NFS), remote login (rlogin), remote shell (rsh) protocol, and remote copy (rcp). Specific protocols that
embed the IP address information within the payload require the support of an ALG. An ALG is used with
NAT to translate the SIP or SDP messages. The NAT Support for SIP feature allows SIP embedded
messages passing through a router configured with NAT to be translated and encoded back to the
packet. An ALG is used with NAT to translate the SIP or SDP messages.
Example – When you are using protocols like SIP, SCCP, RTSP, IP Multicast, MPLS VPN (VRF- Aware NAT),
PPTP Support, IPSec ESP Tunnel Mode in a PAT Configuration
More on this - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-
3s/asr1000/nat-xe-3s-asr1k-book/iadnat-applvlgw.html
8. NAT-PT or NAT Port Translation
Network Address Translation (NAT)-Port Translation (PT) is a migration tool that helps customers
transitions their IPv4 networks to IPv6 networks. NAT-PT allows direct communication between IPv6-
only networks and IPv4-only networks.
Example – When you want to connect completely IPv4 Network to completely IPv6 Network
More on this - http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-
nat/113275-nat-ptv6.html
NAT in Overlapping Networks
The solution involves intercepting Domain Name System (DNS) name-query responses from the outside
to the inside, setting up a translation for the outside address, and fixing up the DNS response before
forwarding it to the inside host. A DNS server is required to be involved on both sides of the NAT device
to resolve users wanting to have connection between both networks. This is called as overlapping NAT
or Twice NAT.
Example - Assume Company A has been assigned a block of IP address for years and now it’s re-assigned
to Company B. Company A do not want to go through all the IP changes in their network and would like
to continue with the same range as Company B. Now what if Company A user wants to access a server
on Company B's network? A DNS request is generated and the device will see that the IP address is local
to Company A. So in order to solve this issue, we must translate both the source and destination
address.
More on this - http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/13774-
3.html
NAT for TCP Load Distribution
By using Network Address Translation (NAT), you can establish a virtual host on the inside network that
coordinates load sharing among real hosts. Destination addresses that match an access list are replaced
with addresses from a rotary pool. Allocation is done on a round-robin basis and only when a new
connection is opened from the outside to inside the network
Example - You have a scenario where, you have a couple of web servers and want to load balance traffic
between them but you don't want to spend a fortune buying Load Balancers.
More on this - http://gns3vault.com/network-services/nat-tcp-load-balancing/
9. NAT with HSRP
NAT with HSRP is different from SNAT (Stateful NAT) it is a stateless system. The current session is not
maintained when failure takes place. During static NAT configuration (when a packet does not match
any STATIC rule configuration), the packet is sent through without any translation.
Example – When you have HSRP configured between two devices
More on this - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_nat/configuration/xe-
3s/asr1000/nat-xe-3s-asr1k-book/iadnat-ha.html
NAT using Route-Maps
The advantage of using route-maps is that under the match command you can have more options other
than source IP address. For example, under the route-map, match interface or match ip next-hop can be
specified. By using route-maps, you can specify the IP address as well as the interface or the next-hop
address to which the packet is to be forwarded. Therefore,
Example - route-maps with NAT are used in a scenario where the subscriber is multi-homing to different
ISPs.
More on this - http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/13739-
nat-routemap.html
NAT with IPSec VPN
The IPSec ESP through NAT feature provides the ability to support multiple concurrent IPSec ESP tunnels
or connections through a Cisco IOS NAT device configured in overload or Port Address Translation (PAT)
mode. The IPSec NAT transparency feature introduces support for IPSec traffic to travel through NAT or
PAT points in the network by addressing many known incompatibilities between NAT and IPSec.
10. NAT/PAT on Cisco ASA
NAT in Routed Mode
When the ASA receives the packet and if it's a new session it will first check security policy configured.
Then, the ASA translates the local source address (10.1.2.27) to the global address 209.165.201.10,
which is on the outside interface subnet. The ASA then records that session and forwards the packet
from the outside interface.
NAT in transparent Mode
Using NAT in transparent mode eliminates the need for the upstream or downstream routers to perform
NAT for their networks. Because the transparent firewall does not have any interface IP addresses, you
cannot use interface PAT. When the ASA runs in transparent mode, the outgoing interface of a packet is
determined by performing a MAC address lookup instead of a route lookup. However, If traffic that is at
least one hop away from the ASA with NAT enabled—The ASA needs to perform a route lookup to find
the next hop gateway; you need to add a static route on the ASA for the real host address.
NAT with Context Mode - Shared Interface using NAT
Each packet that enters the ASA must be classified, so that the ASA can determine to which context to
send a packet. If you share an interface, but do not have unique MAC addresses for the interface in each
context, then the destination IP address is used to classify packets. The destination address is matched
with the context NAT configuration
Difference between NAT on 8.2 and 8.3 +
The main difference between NAT in 8.2 and 8.4 is the command set. With the introduction to network
objects, the configuration differs on 8.2 and 8.4. Network object NAT is a quick and easy way to
configure NAT for a single IP address, a range of addresses, or a subnet. When a packet enters the ASA,
both the source and destination IP addresses are checked against the network object NAT rules. Since
8.3 no longer supports the nat-control command
11. NAT Order of Operation on 8.2 and 8.3 +
Post 8.3 version NAT configurations are divided into 3 sections ( Section 1, 2 and 3 )
NAT Operation in ASA 8.2 and earlier NAT Operation in ASA 8.3+
NAT exemption Twice NAT are by default inserted to the
Section 1 of NAT rules on the ASA
Static NAT, Static Policy NAT, Static PAT,
Static Policy NAT, Static Identity NAT
Network Object NAT rules are always
inserted to the Section 2 of NAT rules
Policy dynamic NAT, NAT with Overlapping
addresses
Twice NAT rules configured with an "after-
auto" parameter will be moved to Section
3 of the NAT configuration
Regular dynamic NAT, Regular identity
NAT
Network Object NAT
All NAT rules that are configured as a parameter of a network object are considered to be network
object NAT rules.
Twice NAT
Twice NAT lets you identify both the source and destination address in a single rule. Specifying both the
source and destination addresses lets you specify that a source address should be translated to A when
going to destination X, but be translated to B when going to destination Y. The destination address is
optional. If you specify the destination address, you can either map it to itself (identity NAT), or you can
map it to a different address. The destination mapping is always a static mapping. Twice NAT also lets
you use service objects for static NAT-with-port-translation. By default, the rule is added to the end of
section 1 of the NAT table (Version 8.3 +).
New Features for ASA Version 9.0+ NAT Updates
New Features for ASA Version 9.5(1)
Carrier Grade NAT enhancements - For carrier-grade or large-scale PAT, you can allocate a block
of ports for each host, rather than have NAT allocate one port translation at a time (see RFC
6888)
New Features for ASA Version 9.1(2)
Support for the ASA CX module and NAT 64
12. New Features for ASA Version 9.0(1)
NAT support for reverse DNS lookups - NAT now supports translation of the DNS PTR record for
reverse DNS lookups when using IPv4 NAT, IPv6 NAT, and NAT64 with DNS inspection enabled
for the NAT rule.
NAT support for IPv6 - NAT now supports IPv6 traffic, as well as translating between IPv4 and
IPv6 (NAT64). Translating between IPv4 and IPv6 is not supported in transparent mode.
Types of NAT
NAT Control
NAT control requires that packets traversing from an inside interface to an outside interface match a
NAT rule; for any host on the inside network to access a host on the outside network, you must
configure NAT to translate the inside host address. Interfaces at the same security level are not required
to use NAT to communicate. However, if you configure dynamic NAT or PAT on a same security
interface, then all traffic from the interface to a same security interface or an outside interface must
match a NAT rule. Similarly, if you enable outside dynamic NAT or PAT, then all outside traffic must
match a NAT rule when it accesses an inside interface. NAT control does not affect static NAT and does
not cause the restrictions seen with dynamic NAT. If you want the added security of NAT control but do
not want to translate inside addresses in some cases, you can apply a NAT exemption or identity NAT
rule on those addresses.
NAT Control 8.2
hostname(config)# nat-control
NAT Control 8.4
There is no nat-control concept in 8.4
NAT Excemption - NAT exemption exempts addresses from translation and allows both translated and
remote hosts to initiate connections.
NAT Excemption - (8.2)
access-list nonat permit ip host 1.1.1.1 host 2.2.2.2
nat (inside) 0 access-list nonat
This tells the ASA, the host is excempted from Natting. Similar to identity nat, but allows outside to
inside initiation, typically used to remove a particular traffic flow from translation
13. Example - Lan to Lan IPSEC with internet access simultaneously
NAT Excemption – (8.4)
8.4 does not have NAT-control concept, so we need to configure Twice NAT
Identity NAT - Identity NAT which is similar to dynamic NAT, you do not limit translation for a host on
specific interfaces. For identity NAT, even though the mapped address is the same as the real address,
you cannot initiate a connection from the outside to the inside (even if the interface access list allows it).
Use static identity NAT or NAT exemption for this functionality.
Identity NAT (8.2)
# static (inside,outside) 10.1.1.1 10.1.1.1 netmask 255.255.255.255
Used to translate an address to itself, only needed when nat-control is on
Identity NAT (8.4)
#object network HOST
# host 10.1.1.1
# nat (inside,outside) static 10.1.1.1
Static NAT—a consistent mapping between a real and mapped IP address. Allows bi-directional traffic
initiation.
Static NAT - (8.2)
#static (dmz, outside) 209.165.201.28 192.168.1.23 mask 255.255.255.0
Permanent translation of public address to private address. Allows outside host to initiate
connection to inside.
Static NAT - (8.4)
#object network DMZ_Network
# host 192.168.1.23 [Real Host]
# nat (dmz,outside) static 209.165.201.28
#access-list outside_in permit ip any host 192.168.1.23 ( real ip should be applied )
#access-group outside_in in out
14. New feature of 8.4 you can specify the translation for an object between multiple interfaces in just 1
line. If we want ASA to perform address translation for our DMZ server on any mapped interface of ASA,
then we can use the "any" keyword in the command
# Object network DMZ_Server
# nat (dmz,any) static 209.165.201.28
Static PAT - PAT translates multiple real addresses to a single mapped IP address by translating the real
address and source port to the mapped address and a unique port
Static PAT - (8.2)
#static (dmz,outside) tcp 10.10.10.10 21 192.168.1.25 2121
Static PAT - (8.4)
#object network FTPSERVER
# host 192.168.1.25
# nat (dmz,outside) static interface service tcp 21 2121
Dynamic NAT - Dynamic NAT translates a group of real addresses to a pool of mapped addresses that
are routable on the destination network
Dynamic NAT - (8.2)
#nat (inside) 1 10.10.10.0 255.255.255.0
#global (outside) 1 100.100.100.10-100.100.100.100
Dynamic NAT - (8.4)
#object network MAPPED_RANGE
# range 100.100.100.10 100.100.100.100
#object network INSIDE_NETWORK
# subnet 10.10.10.0 255.255.255.0
# nat (inside,outside) dynamic MAPPED_RANGE
Translates inside private addresses to pool of public addresses
Note - Does not allow outside host to initiate connection to inside
15. Dynamic PAT—A group of real IP addresses are mapped to a single IP address using a unique source port
of that IP address.
Dynamic PAT - (8.2)
#nat (inside) 1 10.10.10.0 255.255.255.0
#global (outside) 1 interface
Dynamic PAT - (8.4)
#object network INSIDE_NAT
# subnet 10.0.0.0 255.255.255.0
# nat (inside,outside) dynamic interface
*** nat (inside) 1 0 0 means any network on the inside***
Dynamic Policy NAT - Policy NAT lets you identify real addresses for address translation by specifying the
source and destination addresses in an extended access list. You can also optionally specify the source
and destination ports. Regular NAT can only consider the source addresses, not the destination address.
For example, with policy NAT you can translate the real address to mapped address A when it accesses
server A, but also translate the real address to mapped address B when it accesses server B. All types of
NAT support policy NAT, except for NAT exemption. NAT exemption uses an access list to identify the
real addresses, but it differs from policy NAT in that the ports are not considered.
Dynamic Policy NAT (8.2)
# access-list POLICY permit tcp 10.10.10.0 255.255.255.0 host 198.165.201.10 eq 23
# nat (inside) 1 access-list POLICY
# global (outside) 1 100.100.100.1-100.100.100.200
Maps inside ip's to different pools based on ACL
Dynamic Policy NAT (8.4)
Object-nat cannot specify nat conditions based on destination IP
Object-nat cannot configure how to translate the destination ip of the packet
To overcome this we can use Manual NAT or Twice NAT
16. Troubleshooting NAT
Verify layer 2 connectivity
Verify layer 3 routing information
Check access-list configured
show xlate
show conn
show logging
The packet tracer utility can be used to diagnose most NAT-related issues on the ASA
Troubleshooting simple scenario's using packet capture
Run the debug ip nat translations and debug ip packet commands in order to see if the
translations are correct and the correct translation entry is installed in the translation table.
For ASA Version 8.3 +, the evaluation starts at the top (Section 1) and works down until a NAT
rule is matched. Once a NAT rule is matched, that NAT rule is applied to the connection and no
more NAT policies are checked against the packet.
In the case of translating the payload of Domain Name System (DNS) packets, make sure that
translation takes place on the address in the IP header of the packet. If this does not happen,
then NAT does not look into the payload of the packet.
17. NAT/PAT on Cisco Nexus Switches
As far as I know, there are no NAT capabilities on Cisco Nexus 7000 Series Switches.
NAT is only supported on below Nexus Switches
Nexus 9300 Series
Nexus 6000 Series
Nexus 5600 Series
Nexus 3448 Series
ITD support for SLB NAT on Nexus Switches
In SLB-NAT deployment, client can send traffic to a virtual IP address, and need not know about the IP of
the underlying servers. NAT provides additional security in hiding the real server IP from the outside
world. In the case of Virtualized server environments, this NAT capability provides increased flexibility in
moving the real servers across the different server pools without being noticed by the their clients.
With respect health monitoring and traffic reassignment, SLB NAT helps applications to work seamlessly
without client being aware of any IP change
Cisco® Intelligent Traffic Director (ITD) bridges the performance gap between a multi-terabit switch and
gigabit servers and appliances. It provides multiple-terabit Layer 4 load balancing, traffic steering, and
clustering from Cisco Nexus® switches.
NAT Support on various Nexus Switches Models
Nexus
Switches
Nexus
9300 Series
Nexus 7000
Series
Nexus 6000
Series
Nexus
5600 Series
Nexus 4000
Series
Nexus 3548
Series
Static NAT Yes No Yes Yes No Yes
Dynamic
NAT
Yes No Yes Yes No Yes
PAT Yes No Yes Yes No Yes
Twice NAT Yes No Yes Yes No Yes
VRF-Aware
NAT
Yes No Yes Yes No Yes
ITD – SLB
NAT
Yes Yes Yes Yes NA NA
License
Required
FCoE IVR
NAT over
Fibre
Channel
Layer 3 Base
Services
Package
Layer 3
Base
Services
Package
NA Algo Boost
License
NX-OS
Version
Release
7.0(3)I2(1)
Release
6.2(10) –
SLB NAT
Release
7.1(1) N1(1)
Release
7.1(1)
N1(1)
NA Release 6.x
18. Configuration on Nexus Switches for NAT Support
For Nexus Switch 3548 –Example could be found at below link
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus3548/sw/interfaces/602_a1_1/b_N
3548_Interfaces_Config_602_A1_1/b_N3548_Interfaces_Config_602_A1_1_chapter_0101.html
For Nexus Switch 5600 –Example could be found at below link
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5600/sw/interfaces/7x/b_5600_Inte
rfaces_Config_Guide_Release_7x/b_6k_Interfaces_Config_Guide_Release_7x_chapter_01000.html#task
_EF30C89A841A4E2DAF1A9268EF8CBC4D
For Nexus Switch 6000 –Example could be found at below link
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus6000/sw/interfaces/7x/b_6k_Interfa
ces_Config_Guide_Release_7x/b_6k_Interfaces_Config_Guide_Release_7x_chapter_01000.html
For Nexus Switch 9000 –Example could be found at below link
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7x/interfaces/configuratio
n/guide/b_Cisco_Nexus_9000_Series_NXOS_Interfaces_Configuration_Guide_7x/b_Cisco_Nexus_9000_
Series_NX-OS_Interfaces_Configuration_Guide_7x_chapter_01100.html