Cisco 877 - Port forwarding by NAT not working

Discussion in 'Routing & Switching' started by jushin100, Apr 12, 2012.

  1. BrizoH

    BrizoH Byte Poster

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    Very quick reply as I'm at work - but from memory Ethernet0 on an 877 is a virtual interface for the four physical interface, it needs to have a no shut applied (if you've shut it down that is)

    Last time I used an 877 the IP address was configured on eth0 but we had no vlans in place - maybe assign eth0 to vlan10? (if that can be done)
     
    Certifications: CCNA, CCNA Security
    WIP: CCNP
  2. jushin100

    jushin100 Bit Poster

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    My big mistake... I'm working on a 887 not an 877... I hope there is not too much difference
     
  3. ThomasMc

    ThomasMc Gigabyte Poster

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    why not just allow what you need :)
     
    Certifications: MCDST|FtOCC
    WIP: MCSA(70-270|70-290|70-291)
  4. danielno8

    danielno8 Gigabyte Poster

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    Just to confirm:

    When you plug the Cisco in, the internet works for the internal network? And you only lose access FROM THE OUTSIDE to your apps that you have set up port forwarding for?

    How does the internal side of the network connect? You may want to set up a sniffer to see whether you see the traffic on the local network
     
    Certifications: CCENT, CCNA
    WIP: CCNP
  5. Simonvm

    Simonvm Kilobyte Poster

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    Ok, so at home I have it configured like this:

    ip nat inside source static tcp 192.168.33.5 10666 interface Dialer0 10666

    Remove the ACL from your outside interface that allows all IP packets in - NAT will take care of that for you for all return traffic or port forwarding.
    I just checked and I have it set to DENY ALL except those ports that were forwarded in my NAT config.

    You can use the debug command for nat (debug ip nat ...) to find out what is actually happening when you're receiving those packets.
     
    Certifications: MCITP: EST, MCDST, MCTS, A+, N+, CCNP, CCNA Wireless

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