Announcement

Collapse
No announcement yet.

Multiple outside ports to same inside port on same IP

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Multiple outside ports to same inside port on same IP

    Hi all,
    Firstly I am only a home user of Cisco, so my knowledge is limited, so please bear with me. I have a Cisco 837 ADSL router that I use to access servers on my home network.
    My problem:
    For one of the services I would like to switch the outside port to a different port while retaining the old port for a change-over period. So during the change-over both outside ports should port forward to the same inside port.

    I go through the sequence,"login", "en", "show config" and the following line is there;
    ip nat inside source static tcp 192.168.1.5 12000 interface Dialer1 12000

    I then do "config" and then enter the following line
    ip nat inside source static tcp 192.168.1.5 12000 interface Dialer1 12350

    The first time I did it it accepted the line (no errors shown).
    I did "wr" and "wr mem" and then "show config" and the line is not there.
    I did "reload" and then "show config" and the line is still not there.
    I then try to insert the line again and it fails with "static entry in use...", but the line is not there. I then try "telnet <ip> 12350" and it does not connect, so the router is not offereing the port.

    I am a bit lost as I am sure this must be possible and the "in use" message seems to indicate it is somewhere as that is what I get when I try to change an existing line without disabling outside and inside natting first.

  • #2
    Re: Multiple outside ports to same inside port on same IP

    Any help on this will be appreciated. Even just whether this should be possible as maybe I am barking up the wrong tree and it cannot be done.

    Comment


    • #3
      Re: Multiple outside ports to same inside port on same IP

      After much searching found this thread that answers the question:
      http://forums.petri.com/showthread.p...ight=NAT+setup
      So it is not possible to do this, which seems rather restrictive.

      Comment


      • #4
        Re: Multiple outside ports to same inside port on same IP

        I had the same problem.

        I run a mailserver, which listens on 25 (obviously!). However I wanted our office people to be able to send via the same mailserver when travelling, without having to bother with VPNs (they do authenticate though). So I wanted two external ports (e.g. 25 and 3000) to both come into port 25 on the mailserver. But I hit the same limitation.

        In the end I configured Postfix to listen on two ports.



        Jim

        Comment

        Working...
        X