How to allow user use 1 public ip address for access through a Cisco 2600

Posted on 2006-04-20
Last Modified: 2010-03-19
I am trying to figure out is it NAt or Pat not sure. What I need is to allow 192.168.1.x to access the internet using one public ip address. Never done this before and I am lost.
Question by:kvnet
    LVL 27

    Expert Comment

    Is .x one IP or many IP's?

    .x=1 device - one to one NAT
    .x=many devices - many to one NAT (hide behind NAT)
    LVL 1

    Expert Comment


    Try NAT Overload

    Overloading  NAT that maps multiple IP addresses to a single  IP address by using different ports. Known also as PAT (Port Address Translation)

    for more info on NAT u can check at --
    LVL 12

    Assisted Solution

    by:Chris Staunton
    You will need to setup NAT on the 2600 series:

    on your inside interface connected to your 192.x.x.x network you will need to add a command.

    ip nat inside

    on your outside interface connected to your public network you will need to add a command.

    ip nat outside

    If you were given a small subnet from the ISP for instance you would need to create a pool

    ip nat pool Inet(Name of pool) x.x.x.x x.x.x.x (range of ips given) netmask x.x.x.x (netmask given)
    ip nat inside source list 1 pool Inet(name of pool) overload

    you will also need to create an access list for the pool

    access-list 1 permit 192.x.x.x (or whatever reversed subnet mask)


    LVL 10

    Accepted Solution

    Chris post gives you the answer. one thing to add is that if you have just one ip address from ISP you can use
    just that ip so:

    ip nat pool Name_pool  ip-address   ip-address netmask

    hope this helps

    Author Comment

    Lilshoot and fm250 I think you guys are on target. I have jkust a single ip from ISP. WHne I trie creating the pool with the command ip nat pool ISP x.x.x.x(ip address from ISP) I receive the incomplete command error. When I use the ? at the end of the statement it is says I need a netmask. What am I missing.

    LVL 10

    Expert Comment

    are you using
    try this
    ip nat pool pool_name ISP-ip-address ISP-ip-address netmask

    note that "netmask" word need to be there.

    hope this helps

    Author Comment

    Thanks guys that worked. I appreciate your help.
    LVL 10

    Expert Comment

    You are welcome Terry. glad it worked for you

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