CCNA LAB Practice - I. STATIC NAT

Network Address Translation

(NAT)

Objective

Understanding the operation of Network Address Translation. It is used when hosts on LAN do not have globally unique IP Addresses to connect to the internet.

NAT technology enables private IP networks that use non-registered IP addresses to connect to a public network.

The demonstrations include:

1. Static NAT
2. Dynamic NAT.
3. Overload NAT (PAT).

 i. STATIC NAT

In the Static NAT, we map the 1 Private IP Address to 1 reserved Public IP Address.

Diagram

Procedure

1. Configuring & Assigning the IP addresses on the routers R1 & R2.
2. Check the routing table on both the routers.
3. Enable the routing protocol on both routers so that hosts on the both routers can communicate with each other.
4. Check the routing table on both the routers after enabling the routing protocol on both sides.
5. Make a web server to the host C & Run the Sniffer.
6. Establishes Static NAT Translation between an inside local address and an inside global address.
7. Marks the interface as connected to the inside & outside networks.
8. Verifying the Standard Static NAT Translation by commands & Sniffer Outputs.

Configuration         

Step 1(A): Assigning the IP addresses on the Router R1.

R1(config)#interface serial 0

R1(config-if)#ip address 15.0.0.1 255.0.0.0

R1(config-if)#no shutdown

R1(config-if)#clock rate 64000   (Clock Rate will set only DCE Interface)

R1(config-if)#exit

R1(config)#interface ethernet 0

R1(config-if)#ip address 10.0.0.20 255.0.0.0

R1(config-if)#no shutdown

R1(config-if)#end

Step 1(B): Assigning the IP addresses on the Router R2.

R2(config)#interface serial 0

R2(config-if)#ip address 15.0.0.2 255.0.0.0

R2(config-if)#no shutdown

R2(config-if)#end

R2(config)#interface ethernet 0

R2(config-if)#ip address 20.0.0.2 255.0.0.0

R2(config-if)#no shutdown

R2(config-if)#exit

Step 2(A): Check the Routing table of the Router R1.

RA#sh ip route

C    10.0.0.0/8 is directly connected, Ethernet0

C    15.0.0.0/8 is directly connected, Serial0

Step 2(B): Check the Routing table of the Router R2.

RB#sh ip route

C    20.0.0.0/8 is directly connected, Ethernet0

C    15.0.0.0/8 is directly connected, Serial0

Step 3(A): Enable the RIP protocol on the Router R1.

RA(config)#router rip

RA(config-router)#network 10.0.0.0 (Networks to be advertised)

RA(config-router)#network 15.0.0.0 (Networks to be advertised) 

Step 3(B): Enable the RIP protocol on the Router R2.

RB(config)#router rip 10

RB(config-router)#network 20.0.0.0 (Networks to be advertised)

RB(config-router)#network 15.0.0.0 (Networks to be advertised) 

Step 4(A): Check the Routing table of the Router R2 after enabling RIP.

RA#sh ip route

R    20.0.0.0/8 [120/1] via 15.0.0.2, 00:04:42, Serial0

C    10.0.0.0/8 is directly connected, Ethernet0

C    15.0.0.0/8 is directly connected, Serial0

Step 4(B): Check the Routing table of the Router R2 after enabling RIP.

RB#sh ip route

C    20.0.0.0/8 is directly connected, Ethernet0

R    20.0.0.0/8 [120/1] via 15.0.0.1, 00:01:12, Serial0

C    15.0.0.0/8 is directly connected, Serial0

Step 5(A): Make a Web Server to the Host C & Run the Sniffer.

1. Make a Web Page & Save it on Desktop.
2. Go to Start Button > All Programs > Administrative Tool > Internet Service Manager
3. Right Click on the Computer name & goes to New tab > Web Site.
4. Follow the wizard and make the Web Server.
5. Run the Sniffer & capturing the www traffic.

Step 6: Establishes Static NAT Translation between an inside local address

                 and an inside global address.

R1(config)#ip nat inside source static 10.0.0.1 15.0.0.11

R1(config)#ip nat inside source static 10.0.0.2 15.0.0.22

Step 7(A): Marks the interface as connected to the Inside Network.

R1(config)#int Ethernet 0

R1(config-if)#ip nat inside

Step 7(B): Marks the interface as connected to the Outside Network.

R1(config)#int serial 0

R1(config-if)#ip nat inside

Step 8(A): Verifying the Static NAT Translation on Router R1 by translation

                        table command.

R1#show ip nat translations

Pro    Inside global      Inside local       Outside local      Outside global

---        15.0.0.11             10.0.0.1                    ---                       ---

---        15.0.0.22             10.0.0.2                    ---                       ---

Step 8(B): Verifying the Static NAT Translation on Router R1 by debug.

R1#debug ip nat

IP NAT debugging is on

When Host ’A’ pings to Host ‘C’:

00:19:01: NAT: s=10.0.0.1->15.0.0.11, d=20.0.0.1 [34]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.11->10.0.0.1 [34]

00:19:01: NAT: s=10.0.0.1->15.0.0.11, d=20.0.0.1 [35]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.11->10.0.0.1 [35]

00:19:01: NAT: s=10.0.0.1->15.0.0.11, d=20.0.0.1 [36]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.11->10.0.0.1 [36]

When Host ’B’ pings to Host ‘C’:

00:19:01: NAT: s=10.0.0.2->15.0.0.22, d=20.0.0.1 [37]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.22->10.0.0.2 [37]

00:19:01: NAT: s=10.0.0.2->15.0.0.22, d=20.0.0.1 [38]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.22->10.0.0.2 [38]

00:19:01: NAT: s=10.0.0.2->15.0.0.22, d=20.0.0.1 [39]

00:19:01: NAT*: s=20.0.0.1, d=15.0.0.22->10.0.0.2 [39]

Step 8(C): Verifying the Static NAT Translation by Sniffer Output by accessing

                        the Web Server from Host ‘A’.

Step 8(D): Verifying the Static NAT Translation by Sniffer Output by accessing

                        the Web Server from Host ‘B’.