[Discuss] web server can't see out but others can see in

[cra at WPI.EDU (Chuck Anderson)]

On Tue, Sep 25, 2012 at 05:05:08PM -0400, Eric Chadbourne wrote:
> Hi All,
> 
> I have an odd problem.
> 
> I have an unbuntu web sever in virtualbox.  We're sitting behind a
> small business cisco router.
> 
> I did the following:
> 1.  I gave the server a static ip in virtualbox and on the router.
> 2.  Opened port 80 on the cisco device.  Any source and any ip to
> static ip.  Firewall is disabled on server.
> 3.  Enabled One-to-One NAT.  This beast is new to me but nothing
> worked until I did it.

1:1 NAT means that for every IP you have inside the Cisco router, you
need an associated public IP on the outside.  You probably don't have
that.  You probably need 1:Many NAT so you can share a single outside
IP with many inside IPs.

> My web server is visible from the world and is visible on our lan.
> Oddly my server cannot see out.  For example:
> 
> eric at webserver1:~$ ping google.com
> ping: unknown host google.com

What is in /etc/resolv.conf ?

> eric at webserver1:~$ sudo apt-get update
> Err http://us.archive.ubuntu.com precise InRelease

Can you ping your gateway router?  Try pinging the default route from
the results of the "ip -4 route" command:

# ip -4 route
...
default via a.b.c.d dev ethX

# ping -n a.b.c.d