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Is it normal to NOT be able to access an external IP from an internal host that lives on the same network as the other internal host that corresponds to the external IP?

For instance: say I'm on an internal network for widget inc and want to access widget.com which is a public IP with NAT to an internal host called widget1.local. Is it normal to not be able to do so?

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  • It is common, did you not see the list of a dozen or so similar questions questions when you typed in the subject for this question?
    – Zoredache
    Apr 18, 2012 at 0:27

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Is it normal? Well, normal like vehicular manslaughter in a busy city. "Normal" doesn't necessarily mean "desirable" however.

It's called hairpin routing among Cisco people, but has other names (e.g. "tromboning"). Some routers support it, others don't. For example, I don't know about 2012, but three years ago Cisco's IOS did not support hairpin routing.

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  • haha, thanks! Can you expand on the reasons it would be undesirable?
    – CarpeNoctem
    Apr 18, 2012 at 0:30
  • Tromboning is most notably bad for performance reasons. No need to get the SPI / routing engines involved for traffic that's on the same LAN.
    – Wesley
    Apr 18, 2012 at 0:35

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