We have multiple servers running on our network using a ASA 5510 as the firewall and router.

NAT is used to give the servers their external IPs.

When a request made externally using the external IP it works find such as just going to the webpage http://externalip/ but when a request is made internally using the external IP it fails so if you were to be on an internal server and curl http://externalip/ it will timeout. Though if you use the internalip it will work. I am thinking this a routing issue of not being able to go out on an external ip and come back in. Any suggestions would be appreciated.


You are correct, that is not possible. You could set up internal DNS to use the same hostnames (e.g. You have an internal server on that is NATed to Externally, foo.bar.com resolves to Internal DNS (possibly using split horizon if you already run your own) would allow you to do this.)

  • poor mans way could be to use a hosts file on your internal clients – Fergus Jul 12 '11 at 4:59
  • Indeed. The tough part about that is distributing, but possible with a config management system such as Puppet or Chef. – Scott Smith Jul 12 '11 at 19:49

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