08-17-2008 03:14 AM - edited 03-03-2019 11:10 PM
I am trying to configure DHCP and NAT at home on my Cisco 870. Here are the steps I used to create my DHCP:
Router(config)# interface ethernet0/0
Router(config-if)#ip address 172.168.1.1 255.255.255.224
Router(config)# ip dhcp exclude-address 172.168.1.1 172.168.1.4
Router(config)# ip dhcp pool Home
Router(dhcp-config)# network 172.168.1.0 255.255.255.224
Router(dhcp-config)#default-router 172.168.1.1
Router(dhcp-config)exit
But I cant get NAT configured on my 871. Can someone give me a step by step instruction on how this is done. Thanks in advance.
08-17-2008 05:15 AM
Hi,
Just to clarify some things here:
1. What is the interface used to connect to the external network ?
2. What is the interface used to connect to your LAN (home network) ?
If your answer to item 1 is eth0/0 then you probably should assign a private ip address to your internal network not unless you have some servers that needs to be accessed from the outside.
Thanks,
k0rg
08-17-2008 05:52 AM
Hello Christopher,
Here is a sample config for you. I am assuming you are using a dialer interface for outside interface. If you are not, switch dialer command in each line below with your outside interface
interface e0/0
ip nat inside
access-list 10 permit 172.168.1.0 0.0.0.31
ip nat inside source list 10 interface dialerx overload
interface dialerx
ip nat outside
Regards
08-17-2008 06:54 AM
The dailer is what Im confused on. In class we never had a router that used a dailer. Is the "dailerx" the interface I have to use?
08-17-2008 06:58 AM
Christopher,
This interface is generally used to dial ISP and/or provide username&password. It is a vitual interface and usually is bind to an ATM (PPPOA) or an ethernet (PPPOE) interface. The 8xx series are usually used for terminating internet connection in the ways I mentioned above, thats why I advised a config that contains dialer interface.
Please post your full config, and tell us what you exactly want to achieve. If it is a simple NAT to learn NAT in class, you dont need dialer interface.
Regards
08-17-2008 07:12 AM
I will be using my 870 at home to pratice configuring routers. So I guess I just want to setup a simple NAT configuration.
While I dont have the router in front of me, the only problems I have is configuring DHCP and NAT. I think I have DHCP done (except I want to assign IP by MAC Address) but I was confused on the NAT.
08-17-2008 07:41 AM
Please tell us more about the practise you are in right now, and a basic info about the practise lab (what connected to which interface etc), so we will be able to make more stable suggestions on where and how to perform NAT.
08-17-2008 08:00 AM
Well this isnt really a pratice lab, its a Cisco 870 I bought for home use to keep me up to date. Im going to have about 6 devices connected to it through a switch.
08-17-2008 10:30 AM
sorry it suppose to be a private address 172.16 instead of 172.168, my typo.
08-17-2008 03:22 PM
So will these clients connect internet via that router? Is that why you need NAT? You said that you had confusion in NAT part, I am trying to understand where do you want to NAT.
08-21-2008 07:50 PM
Yes these client will connect to the internet so I know that I have to use NAT Overload, but I dont know how to implement it on the 871.
08-18-2008 09:23 PM
Hi Chris,
Please give us an information of what do you want to achieve and the current interfaces and to which interfaces are these users.
This will allow us to give a precise answer to your inquiry.
Thanks,
k0rg
08-21-2008 08:21 PM
how does this NAT config look:
router(config)#ip nat inside source static 172.16.1.1 76.86.132.210
router(config)int f0/0
router(config-if) ip nat inside
router(config-if)int f0/4
route(config-if) ip nat outside
08-21-2008 08:47 PM
or do is this configuration correct:
router(config)# access-list 1 permit 172.16.0.0 0.0.255.255 (or should I use 0.0.0.0)
router(config)#ip nat inside source list 1 int f0/4 overload
router(config)#int f0/0
router(config-if)#ip nat inside
router(config-if)#int f0/4
router(config-if)#ip nat outside
08-21-2008 09:06 PM
Your latest config will translate 172.16.0.0/16 network to interface IP of f0/4 if traffic is destined to a network or gateway connected to f0/4. If this is what you want, config is correct. If you have other networks connected to f0/0 than 172.16.0.0/16, then you can use 0.0.0.0 to include all trafic into translation.
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