[TriLUG] Off Topic: Need Cisco Router Config Help

Chris Bullock cgbullock at yahoo.com
Thu Apr 3 22:30:19 EDT 2008

Sounds to me like your DNS is pointing to your public IP address, and
since you are coming from the inside it will not NAT anything on the
inside.  Again, a simple test it to perform a host private.opennms.com and
see what it resolves to.

If you are inside your network, NAT does not come into play *ever* unless
you have multiple internal subnets.  the only time you will/should NAT is
when you go outside your network or subnet.  The new cisco device can't
NAT an address inside your network unless you have some sort of aliases on
the router that is "answering" on the IP address you want to access.  It
is also possible that the linksys was providing some sort of lookup when a
device pulled dhcp it would  write this in its host file.

--- Tarus Balog <tarus at opennms.org> wrote:

> On Apr 3, 2008, at 7:32 PM, Chris Bullock wrote:
> > First thing I would do is without the help of the host file try to  
> > ping
> > private.opennms.com and see what you get.  Then perform a dig or  
> > nslookup
> > to see exactly what DNS server gave you that IP.
> It's definitely not a DNS issue. It's a NAT issue.
> Let's assume the external address is and the internal LAN is  
> If www.example.com points to, the router will NAT port 80 to  
>  From outside the LAN, http://www.example.com works fine.
>  From inside the LAN, http://www.example.com connects to the router's  
> HTTP server (, thus NAT is not working from the LAN.
> The *workaround* is to set, on the LAN, www.example.com to point to  
> Now, when the router was a Linksys, www.example.com worked in all  
> places. I was wondering if there was something in the way Cisco does  
> NAT to make that work as well.
> -T
> _______________________________________________________________________
> Tarus Balog, OpenNMS Maintainer             Main:   +1 919 533 0160
> The OpenNMS Group, Inc.                     Fax:    +1 503 961 7746
> Email: tarus at opennms.org                    URL: http://www.opennms.org
> PGP Key Fingerprint: 8945 8521 9771 FEC9 5481  512B FECA 11D2 FD82 B45C
> -- 
> TriLUG mailing list        :
> http://www.trilug.org/mailman/listinfo/trilug
> TriLUG Organizational FAQ  : http://trilug.org/faq/
> TriLUG Member Services FAQ : http://members.trilug.org/services_faq/

You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.  

More information about the TriLUG mailing list