No Internet Access Cisco Router

Discussion in 'Computer Networking and Servers' started by finsfree, Feb 16, 2017.

  1. finsfree

    finsfree Member

    I have a Cisco 1841 router.

    The router's internal port (fa 0/1) is configured with a and the external port (fa 0/0) is configured DHCP (get an IP from ISP).

    After plugging in my laptop into port fa 0/1, I can not get internet access. My laptop has an IP address if Right now I'm just trying to ping ( Both the interfaces are up with the "No Shut" command. I am receiving an IP address from my ISP, so I know it is working. I can ping the router's internal and external IP address.

    What am I doing wrong? I have a good concept of computer networking, but I've just never used Cisco's equipment yet. All of the link lights are on (FDX, 100 & Link).


    P.S. I figured since this is very basic you guys should be able to help. I just need internet access for now.
  2. beers

    beers Moderator Staff Member

    You need a NAT Overload statement in order to port forward your LAN addresses behind the outside interface.

    You'd also need a clause to add the gateway address obtained from DHCP as the default route.

    int fa0/1
    ip nat inside
    int fa0/0
    ip nat outside

    access-list 100 remark == [Control NAT Service]==
    access-list 100 permit ip any

    ip nat inside source list 100 interface fa 0/0 overload

    ip route dhcp

    Edit: You likely also want to configure an ACL to limit telnet access and similar from the outside.

    line vty 0 15
    access-class 100 in
    Last edited: Feb 16, 2017
  3. finsfree

    finsfree Member

    Thanks you sir!

    After a couple of videos I got it to work perfectly.

    FYI, I bought this old cisco router and switch online for like cheap and after doing a speed test w/ and speakeasy my speeds are the same. I was expecting a drop in speed. I'm getting 90MB down & 12MB up. Pretty freaking cool!

    1. Cisco 1800 Router IOS version 12.4
    2. Cisco catalyst 3560 PoE-8 switch IOS version 12.2
  4. beers

    beers Moderator Staff Member

    but why
  5. finsfree

    finsfree Member

    I just figured because it was old equipment compared to my newer networking devices. I bought these devices for training.

    My current network consist of a Zyxel USG 20 w/ Netgear AP (802.11ac). I thought for sure replacing these devices with old cisco 10/100MB stuff was going to degrade my network and internet speed, but I was wrong. I may just use it for good;) This [email protected] is awesome!!!

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