Can't see external network; internal network is OK

Hi,

I am setting up a small office network with some Linux boxes
(RHEL, CentOS) and some Windows XP laptops.
These computers are all behind a Netscreen 5GT firewall which
also serves as DHCP server.

>From the Windows computers I can see external hosts
(ISP nameservers, Google, Yahoo).
>From the Linux computers I can see the other hosts on
the local network (both Linux and Windows) and the other
hosts can see the Linux boxes too. But the Linux boxes
cannot see any host (e.g. ISP nameservers, Google's ip
address) external to the local network.

I'm guessing that I've forgotten something very simple.
If you can think of something I should check, I'd be interested
to hear about it.

Thanks for your help,
Robert Dodier

PS. The same equipment was working in a different location,
we're just trying to put Humpty Dumpty back together.

On Fri, 01 Dec 2006 13:29:39 -0800, Robert Dodier wrote:

> Hi,
>
> I am setting up a small office network with some Linux boxes
> (RHEL, CentOS) and some Windows XP laptops.
> These computers are all behind a Netscreen 5GT firewall which
> also serves as DHCP server.
>
>>From the Windows computers I can see external hosts
> (ISP nameservers, Google, Yahoo).
>>From the Linux computers I can see the other hosts on
> the local network (both Linux and Windows) and the other
> hosts can see the Linux boxes too. But the Linux boxes
> cannot see any host (e.g. ISP nameservers, Google's ip
> address) external to the local network.
>
> I'm guessing that I've forgotten something very simple.
> If you can think of something I should check, I'd be interested
> to hear about it.
>
> Thanks for your help,
> Robert Dodier
>
> PS. The same equipment was working in a different location,
> we're just trying to put Humpty Dumpty back together.

Check your GATEWAY setup in your config files under /etc/sysconfig


--

Regards
Robert

Smile... it increases your face value!


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Robert Dodier wrote:

> I am setting up a small office network with some Linux boxes
> (RHEL, CentOS) and some Windows XP laptops.
> These computers are all behind a Netscreen 5GT firewall which
> also serves as DHCP server.
>
> >From the Windows computers I can see external hosts
> (ISP nameservers, Google, Yahoo).
> >From the Linux computers I can see the other hosts on
> the local network (both Linux and Windows) and the other
> hosts can see the Linux boxes too. But the Linux boxes
> cannot see any host (e.g. ISP nameservers, Google's ip
> address) external to the local network.

I figured out the problem -- the Netscreen device was configured with
external/internal ip mappings (MIP in the Netscreen config world)
that were invalid for the new location. After I created new MIP's for
the Linux boxes, they were able to access the outside world.

To delete the old MIP's I had to go to the Policies part of the
Netscreen
config and disable the policies using the old MIP's. Then I was able
to delete them.

I'm posting this info in hopes it can help someone else with a
similar problem.

All the best,
Robert Dodier