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Cisco Router & Cable Modem

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Great Site - Cable Modem & Cisco Router

Good primer...

http://networking-newbie.blogspot.com/2008/10/configure-cisco-router-to-work-with_17.html

 

router> enable
router# configure terminal
router (config) # interface ethernet 0/0
router (config-if)# ip address dhcp
router (config-if)# no shutdown

 


router (config-if)# interface ethernet 0/1
router (config-if)# ip address 192.168.1.1 255.255.255.0
router (config-if)# no shutdown

 


router# show ip interface brief

 


router> enable
router# configure terminal
router (config)# ip dhcp excluded-address 192.168.20.1

 


router (config)# ip dhcp excluded-address 192.168.1.1 192.168.1.10

 


router> enable
router# configure terminal
router (config)# ip dhcp pool HOME_CLIENTS
router (dhcp-config)# network 192.168.1.0 255.255.255.0
router (dhcp-config)# default-router 192.168.1.1
router (dhcp-config)# import all

 


router (dhcp-config)# dns-server 192.168.1.2 192.168.1.3

The above command will send out DNS server address of 192.168.1.2 and 192.168.1.3 to the clients.

 


You can also configure the router to use the above DNS server using the following command in the global configuration mode:
router (config)# ip name-server 192.168.1.2 192.168.1.3

 


You need to remember three basic steps for configuring NAT/PAT:
  1. Create access list to decide which private IP addresses are allowed to be translated by the router.
  2. Issue the NAT command to cooperate NAT with access list that we created and tell the router that we need to overload the requests if you use PAT.
  3. Identify which interface in the router that is connected to the LAN then issue ip nat inside command, and which interface is connected to the internet then issue ip nat outside command.

The steps are not necessarily be in that order, we can start with whichever step first. Here how you do those steps:

Create Access List
router> enable
router# configure terminal
router (config)# access-list 101 permit ip 192.168.1.0 0.0.0.255 any

 


router (config)# ip nat inside source list 101 interface Ethernet0/0 overload

 


router (config)# interface ethernet0/0
router (config-if)# ip nat outside
router (config-if)# interface ethernet0/1
router (config-if)# ip nat inside

 


router (config-if)# exit
router (config)# ip route 0.0.0.0 0.0.0.0 ethernet0/0

 


 

 

 

 

 

Last Updated on Monday, 11 July 2011 22:02