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It is important to secure your Cisco devices by configuring and implementing username and password protection and assigning different Cisco privilege levels to control and restrict access to the CLI. Hence, protecting the devices from unauthorized access. In this article, we will discuss how to configure user accounts and how to associate them to the different Cisco privilege levels. Then, we’ll take a deep dive into their purposes and functions, as well as their importance in network security Level SecurityCisco IOS devices use privilege levels for more granular security and Role-Based Access Control RBAC in addition to usernames and passwords. There are 16 privilege levels of admins access, 0-15, on the Cisco router or switch that you can configure to provide customized access control. With 0 being the least privileged and 15 being the most privileged. These are three privilege levels the Cisco IOS uses by defaultLevel 0 – Zero-level access only allows five commands- logout, enable, disable, help and 1 – User-level access allows you to enter in User Exec mode that provides very limited read-only access to the 15 – Privilege level access allows you to enter in Privileged Exec mode and provides complete control over the By default, Line level security has a privilege level of 1 con, aux, and vty lines .To assign the specific privilege levels, we include the privilege number when indicating the username and password of the admin1 privilege 0 secret Study-CCNA1 Routerconfigusername admin2 privilege 15 secret Study-CCNA2 Routerconfigusername admin3 secret Study-CCNA3In this example, we assign user admin1 a privilege level of 0. Then, we assign user admin2 to privilege level 15, which is the highest level. For admin3, we did not specify any privilege level, but it will have a privilege level of 1 by try to verify the output of our configuration by logging in to each user. Enter the username and the corresponding password, starting with Access Verification Username admin1 Password Router>? Exec commands disable Turn off privileged commands enable Turn on privileged commands exit Exit from the EXEC help Description of the interactive help system logout Exit from the EXEC Router>Notice in the output above that the user admin1 is under User Exec mode and has only five commands- logout, enable, disable, help, and exit. Now, let’s log in as Access Verification Username admin2 Password Routershow privilege current privilege level is 15 RouterThe output above shows that user admin2 is currently in level 15, and we verified that by typing the show privilege’ command on the CLI. Notice also that we are in Privileged Exec mode. Lastly, let’s log in as Access Verification Username admin3 Password Router>show privilege current privilege level is 1 Router>When we logged in as admin3, we verified that it was in level 1 by typing the show privilege’ command on the CLI. Notice that we are in User Exec Levels 2-14You can increase the security of your network by configuring additional privileges from 2 to 14 and associating them to usernames to provide customized access control. This is suitable when you are designing role-based access control for different users and allowing only certain commands for them to execute. Hence, giving them restrictions to unnecessary commands and increasing the layers of security on the now assign privilege level 5 to a user. After that, we will configure privilege level 5 users to be in User Exec mode and allow them to use the show running-config’ admin4 privilege 5 secret Study-CCNA4 Routerconfigprivilege exec level 5 show running-configAll level 5 users now will be automatically accessing the User Exec mode and can now use the User Exec commands such as show running-config’ on the CLI. Let’s log in as user admin4 to verify Access Verification Username admin4 Password Routershow running-config Building configuration... Current configuration 57 bytes ! boot-start-marker boot-end-marker ! ! ! end RouterEnable Secret Command PrivilegeWe can also configure different privilege levels to passwords. Here, we will allow the enable secret’ command to access the Privileged Exec level. Use the enable secret level {level} {password}’ syntax as shown below. The command sets the enable secret password for privilege level secret level 5 Study-CCNA5We can verify our configuration as shown belowUser Access Verification Username admin5 Password Router>show running-config ^ % Invalid input detected at ^’ marker. Router>enable 5 Password R4show privilege Current privilege level is 5 Routershow running-config Building configuration... Current configuration 57 bytes ! boot-start-marker boot-end-marker ! ! ! end RouterIn our first attempt, notice in the example above that we do not have access to the show running-configuration’ command. That is because we are currently under privilege level 0. However, we can log in as a privilege level 5 user with the enable {privilege level}’ command, and from there, we can now access the show running-configuration’ our Free CCNA Study Guide PDF for complete notes on all the CCNA 200-301 exam topics in one recommend the Cisco CCNA Gold Bootcamp as your main CCNA training course. It’s the highest rated Cisco course online with an average rating of from over 30,000 public reviews and is the gold standard in CCNA training
NAT(Network Address Translation) et PAT (Port Address Translation) sont deux techniques utilisées pour pallier le manque d'adresses IPv4. Elles ont comme effet bonus d'augmenter la sécurité. Voyons comment cela fonctionne. Lorsque vous vous connectez à Internet, votre routeur (la box de votre FAI) a une adresse IP extérieure (pour Internet).
With static NAT, routers or firewalls translate one private IP address to a single public IP address. Each private IP address is mapped to a single public IP address. Static NAT is not often used because it requires one public IP address for each private IP configure static NAT, three steps are required1. configure private/public IP address mapping by using the ip nat inside source static PRIVATE_IP PUBLIC_IP command 2. configure the router’s inside interface using the ip nat inside command 3. configure the router’s outside interface using the ip nat outside commandHere is an A requests a web resource from S1. Computer A uses its private IP address when sending the request to router R1. Router R1 receives the request, changes the private IP address to the public one, and sends the request to S1. S1 responds to R1. R1 receives the response, looks it up in its NAT table, and changes the destination IP address to the private IP address of Computer the example above, we need to configure static NAT. To do that, the following commands are required on R1R1configip nat inside source static R1configinterface fastEthernet 0/0 R1config-ifip nat inside R1config-ifinterface fastEthernet 0/1 R1config-ifip nat outsideUsing the commands above, we have configured a static mapping between Computer A’s private IP address of and the router’s R1 public IP address of To check NAT, you can use the show ip nat translations commandR1show ip nat translations Pro Inside global Inside local Outside local Outside global icmp - - -Download our Free CCNA Study Guide PDF for complete notes on all the CCNA 200-301 exam topics in one recommend the Cisco CCNA Gold Bootcamp as your main CCNA training course. It’s the highest rated Cisco course online with an average rating of from over 30,000 public reviews and is the gold standard in CCNA training
Exemplede configuration de l'instruction NAT et PAT sur le pare-feu Cisco Secure ASA Contenu Introduction Conditions préalables Conditions requises Components Used Configurer - Plusieurs instructions NAT avec NAT manuel et automatique Diagramme du réseau ASA versions 8.3 et ultérieures Configurer - Plusieurs pools globaux Diagramme du réseau ASA versions
Published On August 6ᵗʰ, 2019 0207 IP Addressing NAT Configuration Guide, Cisco IOS XE Gibraltar The Network Address Translation 46 NAT 46 feature solves IPv4 to IPv6 connectivity by providing a mechanism for connectivity of IPv4 hosts to IPv6 internet when dual stack and IPv6 tunneling solutions cannot be used. Note NAT 46 is supported only on Cisco ISR 4000 platforms. Feature Information for Connectivity Between IPv4 and IPv6 Hosts Using Stateless NAT 46 Restrictions for NAT 46 Information About NAT 46 Configuring Network Address Translation 46 Verifying the NAT 46 Configuration Feature Information for Connectivity Between IPv4 and IPv6 Hosts Using Stateless NAT 46 The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to An account on is not required. Table 1. Feature Information for Connectivity Between IPv4 and IPv6 Hosts Using Stateless NAT 46 Feature Name Releases Feature Information Connectivity Between IPv4 and IPv6 Hosts Using Stateless NAT 46 Cisco IOS XE Gibraltar Release The Network Address Translation 46 NAT 46 feature solves IPv4 to IPv6 connectivity by providing a mechanism for connectivity of IPv4 hosts to IPv6 internet when dual stack and IPv6 tunneling solutions cannot be used. Note NAT 46 is supported only on Cisco ISR 4000 platforms. Restrictions for NAT 46 Only Domain Name System DNS application layer gateway ALG is supported. Fragmented packet is not supported. Maximum Transmission Unit MTU discovery after converting to IPv6 packets is not supported. Virtual Routing and Forwarding-aware NAT 46 is not supported. Both NAT44 static, dynamic, and PAT configuration and stateful NAT46 configurations are not supported on the same interface. High-speed Logging HSL is not supported. Several IPv4 stateful features PBR, ZBFW, WAAS, WCCP, NBAR, and so on do not work after converting to IPv6 packets, and are not supported. High availability is not supported. Information About NAT 46 Overview of NAT 46 Scalability on NAT 46 NAT 46 Prefix Overview of NAT 46 The NAT46 solution solves IPv4 host to IPv6 internet connectivity. IPv4 hosts trying to reach a server, first initiate a DNS type A query packet. The NAT 46 router changes this to type AAAA query. When the query response is received, NAT 46 retrieves the IPv6 address from the response packet. An IPv4 address is allocated from the configured NAT 46 pool and an address binding is done for the retrieved IPv6 address and the allocated IPv4 address. An IPv4 address DNS response is sent to the IPv4 host. The source address of packets originating from IPv4 hosts is converted using a configured NAT 46 IPv6 prefix. The destination IPv4 address is translated to IPv6 address using pool address binding created during DNS packet flow. Example Configured Prefix IPv4 Address IPv4-Embedded IPv6 Address 20020DB8/96 20020DB8C000221 Scalability on NAT 46 There is no limitation to the number of private IPv4 addresses that can be supported because no sessions are maintained. The number of IPv6 hosts that can be represented by the IPv4 pool address should be scalable up to 40,000. NAT 46 Prefix The NAT 46 prefix cannot be same as the interface prefix. Neighbor Discovery Neighbor/Router Solicitation messages for the addresses in the NAT 46 prefix are not answered by the NAT 46 router. Hence, NAT 46 prefix cannot be same as the interface prefix. If a larger network smaller prefix that is less than 96 is obtained from the service provider, the network can be subdivided into multiple smaller networks and NAT 46 prefix can be configured with a smaller network prefix 96 bits. In addition, the NAT 46 router needs to be configured as a gateway or next hop router for the IPv6 hosts on an adjacent router of the service provider network. Configuring Network Address Translation 46 Procedure Step 1 enable Example Device> enable Enables privileged EXEC mode. Enter your password if prompted. Step 2 configure terminal Example Device configure terminal Enters global configuration mode. Step 3 interface type number Example Deviceconfig interface gigabitethernet 1/2/0 Configures an interface and enters interface configuration mode. Step 4 ip address ip-address mask Example Deviceconfig-if ip address Configures an IPv4 address for an interface. Step 5 nat64 enable Example Deviceconfig-if nat64 enable Enables NAT46 translation on an IPv4 interface. Step 6 exit Example Deviceconfig-if exit Exits interface configuration mode and enters global configuration mode. Step 7 interface type number Example Deviceconfig interface gigabitethernet 0/0/0 Configures an interface and enters interface configuration mode. Step 8 ipv6 enable Example Deviceconfig-if ipv6 enable Enables IPv6 processing on an interface. Step 9 ipv6 address {ipv6-address/prefix-length prefix-name sub-bits/ prefix-lenth Example Deviceconfig-if ipv6 address 2001DB811/96 Configures an IPv6 address based on an IPv6 general prefix and enables IPv6 processing on an interface. Step 10 nat64 enable Example Deviceconfig-if nat64 enable Enables NAT46 translation on an IPv6 interface. Step 11 exit Example Deviceconfig-if exit Exits interface configuration mode and enters global configuration mode. Step 12 nat64 settings nat46 enable Example Deviceconfig nat64 settings nat46 enable Enables NAT46 in the NAT64 settings. Step 13 nat46 v6 prefix ipv6 prefix/prefix-length Example Deviceconfig nat46 v6 prefix 2001/96 Configures the NAT46 IPv6 prefix. Step 14 nat46 v4 pool pool-name pool-address-range Example Deviceconfig nat46 v4 nat46_pool Configures the NAT46 pool address range. Step 15 end Example Deviceconfig end Exits global configuration mode and returns to privileged EXEC mode. Verifying the NAT 46 Configuration Use the show nat64 statistics command to view the NAT 46 statistics. The following is sample output of the command. SUMMARY STEPS show nat64 statistics DETAILED STEPS show nat64 statistics Example Router show nat64 statistics NAT64 Statistics Total active translations 0 0 static, 0 dynamic; 0 extended Sessions found 0 Sessions created 0 Expired translations 0 Global Stats Packets translated IPv4 -> IPv6 Stateless 0 Stateful 0 MAP-T 0 NAT46 30 Packets translated IPv6 -> IPv4 Stateless 0 Stateful 0 MAP-T 0 NAT46 30
StaticNAT (Network Address Translation) is useful when a network device inside a private network needs to be accessible from internet. Dynamic NAT (Network Address Translation) - Dynamic NAT can be defined as mapping of a private IP address to a public IP address from a group of public IP addresses called as NAT pool. Dynamic NAT establishes a
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
Nousallons voir ici comment mettre en place la surcharge de NAT à l’aide d’un routeur Cisco, et avec à notre disposition un pool d’adresses IP Publiques. Dans une configuration où nous
Le Port Address Translation, ou surcharge de NAT, ou NAT Overload, permet de traduire beaucoup d’IP du réseau local en une IP publique ou plusieurs. Au contraire des NAT statiques et dynamiques dont le nombre de sessions simultanées se limitent au nombre d’IP publiques disponibles. Avec le PAT, toutes les IP qui sortent du réseau le feront avec la même IP. Par contre, chaque session se verra attribuer un numero de port TCP ou UDP, couche 4, de transport. Si vous envoyez une requête vers un serveur Internet, votre IP privée sera donc flanquée d’un numero désignant que cette session vous appartient et le routeur vous la retournera correctement. Le numero de port agit comme un identifiant qui indique que cette session a été initiée par telle ou telle ip du réseau local. Je rappelle que dans cet exemple, on va NATER » nos IP privées en IP publiques, mais que le NAT/PAT peut très bien impliquer seulement des IP privées à l’intérieur d’un réseau local. Nous allons voir ici comment mettre en place la surcharge de NAT à l’aide d’un routeur Cisco, et avec à notre disposition un pool d’adresses IP Publiques. Dans une configuration où nous n’aurions qu’une seule IP Publique à NATER, ce n’est pas bien différent, nous le verrons ici aussi. ————————————- -Un petit schéma de topologie pour aider à la reflexion -Dans cette histoire, le but est d’activer le PAT au niveau de R2, afin que tous les PC du réseau local de PC1 à PC9, sortent sur Internet en utilisant un pool d’IP Publiques associées à des ports TCP et UDP. -On considère que le serveur est sur Internet, car même si dans ce schéma tout est routé et tout se pingue, ça revient au même. -Nous n’avons donc rien à faire sur R1 puisqu’il ne sert qu’à router les trois réseaux locaux. Tout se passera donc au niveau de R2. -Notre pool d’IP Publiques contient deux IP de à -Vous pouvez télécharger le fichier Packet Tracer histoire de faire vos propres simulations de requêtes et ainsi vous assurer que les IP sont bien traduites Télécharger le fichier Packet Tracer ————————————- -On prend donc la main sur R2 –>On défini le pool d’adresses publiques qui sera utilisé. Ne tapez cette commande que si vous avez un pool d’IP publiques. Si vous n’avez qu’une IP publique ce n’est pas nécessaire. R2configip nat pool PAT-POOL netmask le nom PAT-POOL est choisi par moi-même, notez bien le nom que vous choisissez car il servira pour lier une ACL. ————————————- –>On créer une liste ACL qui autorisera seulement nos trois réseaux à passer par le NAT. R2configaccess-list 1 permit La donnée représente le masque de sous réseau Pour les ACL on donne en fait les bits d’hôtes, c’est comme ça. Un masque en 24 bits ne laisse que 8 bits d’hôtes, soit Le masque semble donc inversé. R2configaccess-list 1 permit on fait donc la même chose pour chaque réseau local. R2configaccess-list 1 permit *ATTENTION Même dans le cas où vous n’avez qu’une seul IP publique à NATER, vous devez entrer ces commandes puisque vous aurez besoin de cette liste ACL.————————————- –>Puis on paufine la règle NAT en y associant l’ACL et en activant la surcharge NAT. R2configip nat inside source list 1 pool PAT-POOL overload on indique donc que l’on souhaite utiliser la liste ACL numero 1, sur le pool PAT-POOL, et que le NAT doit être en mode overload, autrement dit surcharge, ou PAT. *ATTENTION Si vous n’avez qu’une seule IP Publique à NATER, la manipulation est un peu différente. Dans le cas d’une IP publique unique, on s’y prend un peu différemment -Avec une seule IP Publique, je dois configurer l’interface externe du routeur et lui donner cette IP publique. -Par exemple, je possède l’IP publique -Je vais configurer l’interface G0/0 de R2 pour qu’elle possède cette IP. R2configinterface g0/0 je sélectionne l’interface. R2config-ifip addr je lui assigne mon unique IP publique avec son masque. -Puis j’entre la règle de NAT R2configip nat inside source list 1 interface g0/0 overload On crée la règle NAT en mode overload et qui est basée sur l’IP unique de l’interface G0/0. ————————————- –>Puis on spécifie quelles interfaces du routeur sont à l’intérieur et à l’extérieur R2configinterface s0/0/0 on sélectionne l’interface. R2config-ifip nat inside on spécifie qu’elle est interne à notre réseau privé. R2configinterface g0/0 on sélectionne l’interface. R2config-ifip nat outside on spécifie qu’elle est externe à notre réseau privé. *Pour info, dans le cadre de sous-interfaces, il faut définir ce paramètre sur chaque sous-interface et non sur l’interface réelle. ————————————- –>La surcharge NAT est configurée ! ————————————- -Pour en avoir le cœur net, voyons le résultat d’une simulation -L’enveloppe bleue est un PING envoyé à partir de PC1 qui possède l’adresse source -L’IP de destination du paquet est celle du serveur Internet -Le paquet a traversé le réseau local, toujours en possédant comme IP source. -Comme on peut le voir dans le cadre rouge, en arrivant dans R2 In Layers, le paquet avait l’IP source -Comme on peut le voir dans le cadre rouge, en sortant de R2 Out Layers, le paquet aura l’IP Source *Vous constatez probablement qu’aucun port n’est attribué à notre paquet, la couche de transport n’entre pas en jeu Layer 4. C’est parce qu’il s’agit ici d’un PING, le PING fait partie du protocole ICMP qui n’utilise pas la couche transport, donc pas de port attribué. Il faut savoir que cela est une situation bien spécifique à ICMP et probablement d’autres protocoles. Avec une requête HTTP, le paquet aurait un numero de port source et de destination. A la place, le Ping possède un numéro de séquence dans sa la simulation dans Packet Tracer, en utilisant une requête HTTP au lieu d’une ICMP. Envoyez une requête HTTP simultanément depuis PC1 et PC2 vers le Serveur, vous constaterez que leurs ports seront différent. ————————————- Je vous invite à utiliser le simulateur dans Packet Tracer si vous voulez vous familiarisez avec le processus.
ConfiguringPort Address Translation (PAT) on Cisco devices. With Port Address Translation (PAT), a single public IP address is used for all internal private IP addresses, but a different
Service, Instance, Communication – un ensemble de fonctions mis à disposition d’utilisateurs – une exécution unitaire d’un service pour des participants particuliers q Dans les télécoms un service permet à des partenaires distants d’échanger des médias qUne instance d’un service télécom est une communication’ Zmk23.
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