NAT(Network Address Translation) is a process of changing the source and destination IP addresses and ports. Address translation reduces the need for IPv4 public addresses and hides private network address ranges. This process is usually done by routers or firewalls. Host A request a web page from an Internet server. Laformation Cisco CCNA vous donne un large Ă©ventail de connaissances fondamentales pour toutes les carriĂšres en IT. GrĂące Ă  une combinaison de cours thĂ©oriques et de laboratoires pratiques, vous apprendrez comment installer, utiliser, configurer et vĂ©rifier les rĂ©seaux IPv4 et IPv6 de base. La formation couvre la configuration des Étapespour configurer PAT pour l'image rĂ©seau ci-dessus Ă  l'aide de CLI. Connectez-vous Ă  l'appareil Ă  l'aide de SSH / TELNET et passez en mode activation. Passez en mode config. Staticand dynamic NAT configurations work with PPTP without the requirement of the PPTP application layer gateway (ALG). However, Port Address Translation (PAT) configuration requires the PPTP ALG to parse the PPTP header and facilitate the translation of call IDs in PPTP control packets. NAT then parses the GRE header and translates call IDs for Iwant to configure a PIX 501 firewall for NAT - or more accurately PAT. I want all inside users to be able to access the Internet using their non-routable IP adresses that the PIX will translate at the perimeter. I only have one public IP address available. I do not have a Nousallons voir ici comment mettre en place la surcharge de NAT Ă  l’aide d’un routeur Cisco, et avec Ă  notre disposition un pool d’adresses IP Publiques. Dans une configuration oĂč nous CiscoASA Series Firewall ASDM Configuration Guide 6 Network Object NAT (ASA 8.3 and Later) All NAT rules that are configured as a paramete r of a network object are considered to be network object NAT rules. Network object NAT is a quick and easy way to configure NAT for a single IP address, a range of addresses, or a subnet. After you ASA5506-X Basic Configuration Tutorial. The ASA 5506-X has a default configuration out-of-the-box. This default configuration has the following characteristics: Internal LAN: /24. Internal LAN can access the Internet. The WAN (outside) interface (GE1/1) is configured to receive IP address from DHCP. Whatare NAT and PAT? : explained with the configuration of NAT with PAT in Cisco packet tracer. We will also enable PAT as it immensely increases the capability of NAT. NAT (Network Address Translation) is used to translate the Exolab: DĂ©couverte NAT-RIP via Packet Tracer. IntitulĂ© long. ActivitĂ© Packet-Tracer de dĂ©couverte et de mise en pratique : - Du NAT dynamique et statique - Du routage dynamique avec le protocole RIP, en version 2. Maquette Ă  complĂ©ter par Ă©tape (au dĂ©part, Ă©quipements paramĂ©trĂ©s au niveau des interfaces uniquement) VUvuAtV. Network Address Translation NAT replaces IP addresses within a packet with different IP addresses. NAT is very useful in these instances Conserving IP address space. Implementing TCP load distribution. Connecting networks with overlapping addresses. During network migration, which involves the renumbering of nodes. Connecting a private network using an unregistered address to a public network like the Internet. Distributing other Transmission Control Protocol TCP and User Datagram Protocol UDP based router configured for NAT maintains a translation table that has the mapping between the addresses used in the translation. Configuring NAT involves identifying the NAT inside and NAT outside interfaces, then configuring the way the addresses are to be translated, depending on the requirement. A router configured with NAT translates only traffic that is forwarded between the inside and outside interfaces, and the flow that matches the criteria specified for translation. Traffic that does not meet these conditions is forwarded without any translation. To configure the inside and outside interfaces, issue the ip nat inside and ip nat outside commands under the respective interfaces. A static NAT configuration creates a one-to-one mapping and translates a specific address to another address. This type of configuration creates a permanent entry in the NAT table, as long as the configuration is present and is useful when users on both inside and outside networks need to initiate a connection. To configure static NAT, issue the ip nat inside source static or ip nat outside source static commands in global configuration mode, depending on where the host is located. Static NAT can also be used to redirect traffic using a particular port to a different port on a host. This is helpful when the users belonging to the inside network use a particular port number to access a particular application like a web server available on the inside or outside network. The same application is accessed by users from the outside network using a different port number. To redirect traffic to a different port, issue the ip nat inside source {static {tcpudp local-ip local-port global-ip global-port} [extendable] or ip nat outside source {static tcpudp global-ip global-port local-ip local-port} [extendable] commands in global configuration mode, depending on whether the inside or outside network is available. Another type of configuration is dynamic NAT, which is useful when a limited number of addresses is available instead of the actual number of hosts to be translated. The addresses used for translation are configured by issuing the ip nat pool command in global configuration mode. The hosts to be translated are specified by issuing the access-list command or match statements in the route-map command. The pool and the list of hosts to be translated are linked together by issuing the ip nat inside source list name pool name command or the ip nat inside source route-map name pool name command in global configuration mode. The command can be issued for an outside network by replacing the keyword "inside" with "outside". Dynamic NAT creates an entry in the NAT table, when the host initiates a connection and establishes a one-to-one mapping between the addresses. But the mapping could vary depending on the address available in the pool at the time of communication. Dynamic NAT allows sessions to be initiated from inside or outside networks for which it is configured. Dynamic NAT entries are removed from the translation table if the host does not communicate for a specific period of time, which is configurable, and the address is returned to the pool for use by another host. Another form of dynamic translation is overloading or Port Address Translation PAT, which allows many hosts to be mapped to a single address at the same time. When PAT is configured, the router makes use of the source port numbers to distinguish the sessions from different hosts. PAT creates an extended translation entry in the NAT table by including the protocol as well as the port information. PAT is configured by adding the overload option to the dynamic NAT configuration command, which binds the hosts and the pool. Static and dynamic NAT can be configured simultaneously when it is required. This occurs in cases where many addresses are not available for translation, and certain devices must be statically configured for NAT at the same time. For more information on configuring NAT refer to these documents NAT Local and Global Definitions Configuring Static and Dynamic NAT Simultaneously Configuring Network Address Translation Getting Started View more Cisco How-To Tutorials Search 54,082 current Cisco Job openings worldwide! Join the Network World communities on Facebook and LinkedIn to comment on topics that are top of mind. Brad Reese is research manager at advancing the careers of 600,000-plus certified individuals in the growing Cisco Career Certification Program. Copyright © 2008 IDG Communications, Inc. Configuring NAT for multiple Vlans on a Cisco router is a challenge that many inexperienced Cisco network engineers have had to contend with at one stage of their careers or the other. While NAT implementation is really not a big deal, its successful implementation on a Cisco router configured for multiple vlans can give you a grief, if you do not know what you are doing. In my previous post, I shared with us on how to configure dhcp on a Cisco router with multiple vlans. You can find it here. In this post, using a slightly modified version of the previous network topology, I will share with us on how to configure NAT for multiple vlans on a Cisco router. Network topology Objective Our objective in this lab is to configure NAT for the three vlans represented in the network topology. We can NAT all three vlans to one public IP or to separate public IPs. For this demonstration, each vlan will be NATed to the public IP on the WAN interface of the router. Public IPs to be used in the NAT for multiple vlans Vlan 10 private subnet= Public IP= Vlan 20 private subnet= Public IP= Vlan 30 private subnet= Public IP= You may also like How to redistribute static routes into eigrp using Cisco Packet Tracer Configuring NAT for multiple vlans First, we create three access-lists to match the private subnets. Routerconfigaccess-list 10 permit Routerconfigaccess-list 20 permit Routerconfigaccess-list 30 permit Next, we create pools for the vlans. Routerconfigip nat pool timigate netmask Configure the NAT statement. Each statement will reference corresponding access-list and NAT pool for that vlan. See below. Routerconfigip nat inside source list 10 pool timigate overload Routerconfigip nat inside source list 20 pool timigate overload Routerconfigip nat inside source list 30 pool timigate overload The final step is to define the inside and outside interfaces. This is where most people run into trouble. They use the physical interface instead of the sub-interfaces. Where sub-interfaces are used for vlans, these sub-interfaces must be defined and used as the NAT inside interfaces. See below. Routerconfigint f0/1 Routerconfig-ifip nat outside Routerconfigint f0/ Routerconfig-subifip nat inside Routerconfig-subifint f0/ Routerconfig-subifip nat inside Routerconfig-subifint f0/ Routerconfig-subifip nat inside Routerconfig-subif Verification To verify that NAT is working as it should, we turn on debug on the router, using the debug ip nat command. After that, we run a ping from the computers on the LAN to the ISP router. The output below will be displayed on the core router. From the output above, we can see the source address being translated to as it heads out to destination and on the second link we see the reverse process of going to destination before it gets directed to I have covered the configuration of static NAT and dynamic NAT in previous lessons, now it’s time for PAT. This is the topology we’ll use Let’s prepare the hosts. I am using normal Cisco routers with “ip routing” disabled to turn them into dumb hosts Host1configno ip routing Host1configdefault gateway Host2configno ip routing Host2configip default-gateway Next step is to configure NAT NATconfiginterface fastEthernet 0/0 NATconfig-ifip nat inside NATconfiginterface fastEthernet 1/0 NATconfig-ifip nat outside So far so good, let’s create an access-list that matches both hosts NATconfigaccess-list 1 permit And finally we’ll configure PAT NATconfigip nat inside source list 1 interface fastEthernet 1/0 overload I select access-list 1 as my inside source and I will translate them to the IP address on FastEthernet 1/0. The big magic keyword here is overload. If you add this we will enable PAT! Let’s give it a test run shall we?