How to configure dynamic nat in cisco router using packet tracer step by step guide

How To Configure Dynamic NAT in Cisco Router | In this article we will learn what is dynamic  nat , how to configure dynamic  nat and after configuring verify the dynamic  nat in cisco router using packet tracer software.

Suppose in an organization we have reserved private network (192.168.1.0/24) to use to communicate among the users. If all users want to access to the internet then dynamic nat plays an important role to fulfill this requirement.

Private ip address Range

Class A => 10.0.0.0  to 10.255.255.255

Class B => 172.16.0.0 to 172.31.255.255

Class C=> 192.168.0.0 to 192.168.255.255

 Type of NAT

Three types of nats are available.

•   Static nat
•   Dynamic nat
•   Natoverloading(PAT)

What is Dynamic NAT

In the dynamic nat router is configured a pool of ipv4 address . when user want to access to internet then node request to router to mapping public ip address to the corresponding private ipaddress. 

Lab Diagram

 

                           How to configure dynamic  nat in cisco router using packet tracer

In the above diagram we configure dynamic nat in cisco router using packet tracer software.

Configuration of dynamic nating

To configure dynamic nat below some steps we have to follow.

1. Create a pool of public ip addresses to the router to map the private ip addresses.
2. Create an access list to permit ip addresses which to be translated.
3. Map the pool to the access list.
4. Finally apply nat configuration  to the router interface.

In  the above diagram we have a private network 192.168.1.0/24 which to be mapped to public network which is 15.100.60.0/27. To configure it we follow the below steps.

Router(config)#ip nat pool mypool 15.100.60.3 15.100.60.30 netmask 255.255.255.0

Router(config)#ip access-list extended mypool

Router(config-ext-nacl)#permit ip 192.168.1.0 0.0.0.255 any

Router(config-ext-nacl)#exit

outer(config)#ip nat inside source list mypool pool mypool

Router(config)#int gig0/0

Router(config-if)#ip nat inside

Router(config-if)#exit

Router(config)#int se0/0/0

Router(config-if)#ip nat outside

Router(config-if)#exit

Router(config)#

verify of dynamic nating

After configuring dynamic nating we need to verify it. To verify it we execute the below command.

Router#sh ip nat statistics

Total translations: 0 (0 static, 0 dynamic, 0 extended)

Outside Interfaces: Serial0/0/0

Inside Interfaces: GigabitEthernet0/0

Hits: 0 Misses: 0

Expired translations: 0

Dynamic mappings:

-- Inside Source

access-list mypool pool mypool refCount 0

pool mypool: netmask 255.255.255.0

start 15.100.60.3 end 15.100.60.30

type generic, total addresses 28 , allocated 0 (0%), misses 0

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How to configure enable/secret password of cisco router step by step guide

How to configure enable/secret password of cisco router

In this article we learn how to setting enable password of the cisco router. Different types of password you can configured to access the cisco router such as enable password ,secret password, for ssh connection and so on.

Set up enable password of cisco router for demo

To secure a router we configure enable password. It uses to move the mode from user execution mode to privileged execution mode and as well as we can access global configuration mode using enable password.

To configure the enable password of the cisco router we execute the  below command .

Router>en

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#enable password cisco

After execution the above command we create the enable password of the cisco router which is stored in the config file of the router. To find the line from the config file we execute the below command.

Router>en

Password:

Router#show running-config | include enable

enable password cisco

We saw fom the above output that the stored password is in plain text it is not a encrypted format .anyone can read the the stored password from the config file because it is in plain text.

To overcome the problem create a new type of password called secret password .it is not in plain text it is stored in the configuration file in encrypted format which is not readable from anyone .

 Set up secret password of cisco router for demo

To overcome the problem create a new type of password called secret password .it is not in plain text it is stored in the configuration file in encrypted format which is not readable from anyone . when we configure secret password it take over the responsibility to move the mode from user execution mode to privileged execution mode. To configure the secret password we execute the below command.

Router#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Router(config)#enable password cisco

Router(config)#enable secret cisco123

Note: you can not use same password in the secret password which you use to create enable password.

To view the configuration file we execute the below command.

Router>en

Password:

Router#

Router#show running-config | include enable

enable secret 5 $1$mERr$5.a6P4JqbNiMX01usIfka/

enable password cisco

How to configure enable/secret password of cisco router

In next article we learn how to reset enable password of the cisco router with practical demotration.

Howto reset forgot enable password of cisco router with practical demo

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Configure Cisco ASA security level with practical example

Configure Cisco ASA security level with practical example

In the previous article we learned about about what is security level of cisco ASA firewall ,different types of security levels, different types of security zones and in this article we learn how to configure cisco ASA firewall security level and check the traffic from the interface.

Explain Cisco ASA security level with practical example

Types of Cisco ASA security levels

There are three types of security levels.

Security level 100 is the highest security level on the Cisco ASA firewall and by default it it assigned the inside interface of the cisco ASA firewall. As it has highest security level traffic from internal network can roam any where. As security level is higher for the inside zone than the other zone thus traffic from the inside zone move to the DMZ zone as well outside zone.

Security level 0 is the lowest security level on the  cisco ASA firewall and by default it is assigned to the outside interface of the cisco ASA firewall. As it is lowest security level traffic from the outside interface  can not reach the internal network unless we apply policy within the access-list. For the outside zone security level is lower than inside zone as well as DMZ zone therefore traffic from the outside zone can not move to inside zone as well as DMZ zone.

Security level<1-99> is the another security level you can create any security level. Lets take an example suppose we create a DMZ zone and give one security level which is 50.traffic from the DMZ zone move to outside interface as dmz security level is higher than outside security level and traffic from the inside interface move to DMZ zone because inside security level is higher than DMZ level but traffic from the DMZ zone can not reach to inside interface because inside interface has security level which is higher the security level of DMZ zone.

When we are going to configure security level of cisco ASA firewall security level 100 is automatically set for the inside zone and security level 0 is assigned for the DMZ zone and outside zone. We manually configured  DMZ security level 50 to configure cisco ASA firewall.

Lab Diagram

 

Configure Cisco ASA security level with practical example

From  the above diagram we configure cisco ASA firewall security level. Suppose in the inside zone we have network 192.168.3.0/24 , in the dmz zone we have network 192.168.4.0/24 and  in the outside zone we have network 192.168.5.0/24.

How to Configure  Cisco ASA security level

To configure cisco ASA security level we need to configure the interface using below commands.

For inside zone

Ciscoasa (config)#interface E0/0

Ciscoasa(config-if)#nameif INSIDE

Ciscoasa(config-if)#ip address 192.169.3.2 255.255.255.0

Ciscoasa(config-if)#no shutdown

For DMZ zone

Ciscoasa (config)#interface E0/1

Ciscoasa(config-if)#nameif DMZ

Ciscoasa(config-if)#ip address 192.169.4.2 255.255.255.0

Ciscoasa(config-if)#no shutdown

For outside zone

Ciscoasa (config)#interface E0/2

Ciscoasa(config-if)#nameif OUTSIDE

Ciscoasa(config-if)#ip address 192.169.5.2 255.255.255.0

Ciscoasa(config-if)#no shutdown

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Explain brief Introduction of Administrative Distance of router with practical example

Explain brief Introduction of Administrative Distance of router with practical example

In this article we learn what is administrative distance , How is impact the routing decision and default Administrative value of routing protocols.

What is Administrative Distance

Administrative distance is the feature of all routers to select the best trusted route when two or more different routes are there to reach the same destination. Administrative Distance number always in between 0 to 255.

Default Administrative Distance value of different routing protocols

For IGRP Administrative Distance value is 100

For EIGRP Administrative Distance value is 90

For RIP Administrative Distance value is 120

For OSPF Administrative Distance value is 110

For ISIS Administrative Distance value is 115

For STATIC ROUTE Administrative Distance value is 1

For DIRECTLY CONNECTED ROUTE  Administrative Distance value is 0

Sample diagram to explain Administrative Distance

 

Explain brief Introduction of Administrative Distance of router with practical example

Suppose route1 wants to reach to router4.To reach the router4 there are 3 possible route.

One is router1=>router0=>router4

Second is router1=>router2=>router3=> router4

And third is router1=>router5=>router6=>router7=>router8=>router4.

First route takes 2 hops to reach router4.Second route takes 3 hops to reach route4 and third route takes 5 hops to reach router4.

If we taken rip protocol we know that rip is calculate its best route using hop counts. Least hop count consider as the best route among the three. Here route one is the best route for the rip protocol.

For ospf and eigrp bset route is calculated using band width. if first route has band width  3mbps,second route has bandwidth 4mbps and third route has band width of 8mbps,then eigrp and ospf takes third route to reach the destination.

When network admin configure static route he/she decides the best route among the three. Suppose here network admin select second route to reach the destination.

Now router have consider best trusted route using the administrative distance. In the above scenario router select second route to reach the destination as static route has administrative distance which is 1.

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Introduction of Load Balancer with example

Introduction of Load Balancer with example

In this article we learn what is load balancer, feature of load balancer and different type of algorithms used by a load balancer to distribute load traffic to the backend servers.

Load balancer has a feature to distribute load traffic to the backend servers. It is used to increase performance ,scalability and availability to access the service in the large traffic environment.

Normally load balancer is used to  load traffic to the backend servers.  Lets take an example if in an organization existing web server is overloaded by hitting huge no of traffic into the server, to fast the processing speed of the web server we need to add extra one or many web server  to access web portal from the outside world. Now we place the load balancer top of the web servers to distribute traffic to all the web servers equally.

                                      Introduction of Load Balancer with example

Feature of Load Balancer

Load balancer has one feature which is it checks periodically server health. If a server failed the load balancer detect the problem and bypass the server and allocate the entire load to the other live server to maintain the high availability. we can manage logical server from the load balancer.

Other feature is that persistency. It provides persistence feature to allow user to connect their connection to the same server. this feature is very helpful when we are taking about ecommerce site. When  users purchasing some online things via online  shopping cart they are using same server though this feature of load balancer.

Other feature is that cookies persistence. when user login a website load balancer sent the cookies to end user system .user can surfing website without relogin but it has time frame.when it is expired user has to login again to access the website.

Algorithms of Load Balancer

Round robin : Normally it is used in the load balancer to distribute traffic to all servers equally. First connection send to the first server and next connection send to the next server and so on.

Shortest path:  it calculates the path matric which path is short to reach the server.

Server weight:server weight assigns to all servers and traffic is distributed to the servers according against their assign value. if server1 has a value which is 1 and server2 has a value which is 3 then load balancer sends 3 times more traffic to server2.

Least connection: load balancer send the traffic to the server which has lowest no of open connection.

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How to reset forgot enable password of cisco router with practical demo step by step

How to reset forgot enable password of cisco router with practical demo

In this article we learn if we forgot enable password of cisco router how to reset it successfully. It is very common trouble shooting of a network administrator. To secure cisco router we use enable password .it uses to move the user execution mode to privileged execution mode. 

When we enter wrong password  we got the below error.

Router>en

Password:

Password:

Password:

% Bad secrets

How to reset forgot enable password of cisco router with practical demo

Note: after enter three times wrong password we got the above error.

To break the router password we follow the below steps.

Show the current IOS version  of router

 First we have to note down the current IOS register version of the router to do this we execute the below command.

 Router>show version

Current version is 0x2102

Boot the route in ROMMON mode

In the second step we boot the router in ROMMON mode .to boot in the ROMMON mode switch off the router we it is booting up press “ctrl+c” to enter the ROMMON mode.

Change the configure register version

After enter the ROMMON mode we need to change config register version to 0x2142 and then reboot the router.

ROMMON> confreg 0x2142

ROMMON>reset

After change the config register router bypass the startup configuration where password is stored.

Copy startup config to running config

After that copy startup config to running config. To do this we execute the below command.

Router# copy startup-config running-config

Reconfigure the enable password

Now reconfigure the enable password . to configure it  visit this below reference

 How to configure enable/secret password of cisco router

change the original version of configuration register 

Now we need to change the original version of configuration register that is 0x2102.to do this we need to enter config mode and execute the below command.

Router(config)# config-register 0x2102

Now save the configuration and reboot the router .

After doing all the steps we reset the forgot enable password of the cisco router.

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HOW TO CONFIGURE EIGRP ON CISCO ROUTER USING PACKET TRACER SOFTWARE STEP BY STEP GUIDE

HOW TO CONFIGURE EIGRP ON CISCO ROUTER USING PACKET TRACER SOFTWARE

In this article we learn how to configure EIGRP and how to verify EIGRP after configuration on cisco router using packet tracer software.

Introduction of EIGRP

What is EIGRP

EIGRP is called  advanced distance vector and it is  classless protocol. It is a standard protocol and use for cisco and non cisco device, but initially it was cisco proprietary.  It is included all features of igrp. It supports upto 255 hop count and by default it supports upto 100 hop count.

Administrative distance of EIGRP is 90.It does not uses broadcast address .It only uses multicast and unicast address.

By default EIGRP uses bandwidth and delay to calculate the metric calculation.

Lab diagram

               HOW TO CONFIGURE EIGRP ON CISCO ROUTER USING PACKET TRACER SOFTWARE

In the above diagram we learn the configuration of EIGRP on cisco router using packet tracer software.

Configuration of EIGRP on cisco router using packet tracer

We have to follow two commands to configure EIGRP on cisco router. To enabling the EIGRP we use “router eigrp <AS NO>” (AS is the autonomous system no which should be same ,if as no is different routers can not build eigrp neighbour relationship). Secondly router has to advertise their network to configure the EIGRP.

For router0

#router eigrp 1

#network 10.0.0.0

#network 172.16.0.0

For router1

#router eigrp 1

#network 172.16.0.0

#network 192.168.1.0

verify of EIGRP on cisco router using packet tracer

After configuration we need to verify the configuration whether it is configured successfully or not. To verify the the neighbour table on the router0 we execute the below command.

Router#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

0 172.16.0.2 Se0/0/0 13 00:00:42 40 1000 0 4

To verify the topology table from the router0 we execute the below command.

Router#sh ip eigrp topology

IP-EIGRP Topology Table for AS 1/ID(172.16.0.1)

Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,

r - Reply status

P 10.0.0.0/8, 1 successors, FD is 5120

via Connected, GigabitEthernet0/0

P 172.16.0.0/16, 1 successors, FD is 2169856

via Connected, Serial0/0/0

P 192.168.1.0/24, 1 successors, FD is 2172416

via 172.16.0.2 (2172416/5120), Serial0/0/0

To verify the routing table from router0 we execute the below command

Router#sh ip route

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

* - candidate default, U - per-user static route, o - ODR

P - periodic downloaded static route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C 10.0.0.0/8 is directly connected, GigabitEthernet0/0

L 10.0.0.1/32 is directly connected, GigabitEthernet0/0

172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks

C 172.16.0.0/16 is directly connected, Serial0/0/0

L 172.16.0.1/32 is directly connected, Serial0/0/0

D 192.168.1.0/24 [90/2172416] via 172.16.0.2, 00:04:12, Serial0/0/0

Thanks for learning this article. If you like this article please like ,share and comment for this article.   

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Intoroduction of EIGRP and how EIGRP works

Intoroduction of EIGRP

In this article we learn about the feature of EIGRP ,how EIGRP works and in the next part we learn the configuration of EIGRP for demotration purpose using packet tracer software.

Feature of EIGRP

EIGRP is called  advanced distance vector and it is  classless protocol. It is a standard protocol and use for cisco and non cisco device, but initially it was cisco proprietary.  It is included all features of igrp. It supports upto 255 hop count and by default it supports upto 100 hop count.

Administrative distance of EIGRP is 90.It does not uses broadcast address .It only uses multicast and unicast address.

By default EIGRP uses bandwidth and delay to calculate the metric calculation.

Type of EIGRP table

There are three types of tables which EIGRP protocol uses.

·         Neighbour table

To show the neighbour table we use the below command.

#show ip eigrp neighbour

·         Topology table

To show the topology table we use the below command.

#show ip eigrp topology

·         Routing table.

To show the routing table we use the below command

#show ip route

How EIGRP works

In this section we learn how to EIGRP works.

Suppose we have two routers.

STEP1: when router1 is advertising its interface then it send a hello packet to router2 using 224.0.0.10 multicast address. Router2 can not understand the the message unless it advertise its interface. After router2 advertises ites interface it also send a hello message to router1 using unicast address. After exchanging hello messages they build a neighbour table.

STEP2:  After established the neighbour table they exchange their routing information to each other and select the all best path and build a topology table.

STEP3:  After completing step2 they chose the top best route among the best routes and build a routing table.

                                       Intoroduction of EIGRP

HOWTO CONFIGURE EIGRP ON CISCO ROUTER USING PACKET TRACER SOFTWARE.

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How to configure nat overload in cisco router using packet tracer step by step guide

In this article we will  learn what is  nat overload(PAT), how to configure  nat overload in cisco router using packet tracer software.

Normally we use private ip inside the organization which is not allow to users to access the internet,then we use dynamic nat to fulfill our purpose. If ISP not provides organization pool of ip address then we go the another option which is called NAT overload(PAT).

Private ip address Range

Normally we use private ip address which is reserved inside the organization to communicate internal purpose which is not public ip address. The ange are given below.

Class A => 10.0.0.0  to 10.255.255.255

Class B => 172.16.0.0 to 172.31.255.255

Class C=> 192.168.0.0 to 192.168.255.255

Type of NAT

Three types of nats are available.

•   Static nat
•   Dynamicnat
•   Natoverloading(PAT)

What is NAT overload

In the dynamic nating we saw that ISP provides us a pool of public ip address to map with internal private ip to access internet. If ISP gives us few public ip addresses or 1 public ip address instead a pool of public ip addresses to map internal private ip addresses to access internet. In this scenario NAT overload is configured to overcome the problem.

Lab Diagram

                         How to configure nat overload in cisco router using packet tracer

In the above diagram we configure nat overload in cisco router using packet tracer software.

Configuration of NAT overload(PAT)

If ISP gives us few ip addresses or even 1 ip address so we can eliminate the netmask keyword from the dynamic nating command.

Router(config)#ip nat pool mypool 15.100.60.3 15.100.60.4

Router(config)#ip access-list extended mypool

Router(config-ext-nacl)#permit ip 192.168.1.0 0.0.0.255 any

Router(config-ext-nacl)#exit

Here we use only two public ip addesses to map with the internal private ip addresses.Finally we bind the access list with pool and use overload keyword end of the command.

Router(config)#ip nat pool inside source list mypool pool mypool overload

In this article we have   learned what is  nat overload(PAT), how to configure  nat overload in cisco router using packet tracer software.

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