see my network diagram. I can't access internet from LAN network.

enter image description here

I did the following configurations in cisco 1800 router.

1.configured ip address for interfaces.

2.configure ip routing

ip route

3.set defualt gateway

ip default-gateway

I can able to ping and traceroute from the router to google.com. But the users not able to.


You shouldn't set a default gateway in your router since you are routing. The static default route is good enough.

I assume you have private addressing for your network. You will need to configure NAT to translate your private addresses to the public address of the WAN interface. Google, and other Internet sites, cannot send return traffic to private addresses since the private addresses cannot be routed on the Internet.

Also, you really, really, really, need a firewall. Every time I set up something connected to the Internet, within 5 minutes, I can log a dozen attempts to break into what I just set up.

Edit based on the comment that there is a router between the Cisco router and the Internet:

Your Internet router doesn't know about the network behind your Cisco router. Somehow, either using a static route or dynamic routing between the two routers, it need to know that traffic for the network should go to

You could also NAT on the Cisco to accomplish this, but that in not an ideal solution.

  • i have a router in between this router and internet provided by the ISP. So i didnt use NAT. i am beginner, please correct me Oct 30 '15 at 13:55
  • You need to edit your drawing to reflect what you really have because it makes a huge difference.
    – Ron Maupin
    Oct 30 '15 at 13:57
  • I edited my answer to take into account your unknown router.
    – Ron Maupin
    Oct 30 '15 at 14:03
  • updated the image. So i think i use NAT in my router. am i right ? Oct 30 '15 at 14:05
  • Your R2 is using NAT, but it doesn't know about You either need to put in a static route to that network, or you need to run a routing protocol between it and the Cisco so that it can learn about the new network.
    – Ron Maupin
    Oct 30 '15 at 14:07

Do you had set the gateway on your computers?? I guess:

One question: It is a real scenario?, or is just some simulation for testing purpose. The thing is that from internet, it must not know the existence of network

From internet cloud, must exist a route to destination, across With that conf, your scenario must work.

  • yes, I configured the gateway as i can able to ping to Oct 30 '15 at 13:21
  • I edited the answer. Look it. Oct 30 '15 at 13:38
  • this scenario for a testing purpose. is directly connected network. do i need to add static route for that ? see my "show ip route" command result C is directly connected, FastEthernet0/0 is subnetted, 1 subnets C is directly connected, FastEthernet0/1 S* is directly connected, FastEthernet0/1 Oct 30 '15 at 13:47
  • This command "show ip route" you print it on the router, ok. See, between the router and the internet cloud, existe the network, that is the reason why a ping from router reaches internet and internet reaches the router. But, internet do not know how to reach one network behind the router, there only know the network directly connected. You must set on the cloud a default route like this "ip route, or a default gateway. REMEMBER, this must be made ON THE CLOUD!! Oct 30 '15 at 13:55
  • I already seen your editing. It is what i say to you, you need to put on R2 this: "ip route Oct 30 '15 at 14:43

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