On Sat, 2002-01-05 at 20:27, James wrote:
> If it was too long for the subject line:
> 
> Internet <---> 486 firewall & NAT <---> Workstation


On your side of the firewall you have a private network.  There is an
RFC defining this but it is either 10.?.?.? or 192.168.0.? (172 as well
from memory).  Picking one,  198.162.0.?

The firewall is your gateway to the world. On one side it has the
hostile internet on the other it has your safe private network. There
are two network cards in the firewall,  internet and private.  If you
can find cheap 10 base cards then they are all you need for this.  If
you are paying $30 per card then you should be buying 10/100 cards. 
Cards are described in the enternet howto (invaluable for old cards!)

The firewall/gateway will have one side connecting to the internet. 
This is typcially DHCP to dynamically pick up an IP address.  This is
provided by the dhcpcd client.  This will create your resolv.conf on
your gateway.

To test your outside ping connection ping something, ping slug.org.au. 
This should resolve to an IP (138.25.7.4) and get the packets,  if it
does not then ping the ip address above.  If this pings then you
resolv.conf is not working.

The private network side of the gateway it is easiest to use static.  It
is traditional to use ?.?.?.1 as the gateway for a network.  Sticking
with this and using 198.162.0.? as out network we set the IP address of
the second ethernet card to 198.16.0.1 the netmask is 255.255.255.0.

You work station is going to talk to a network (198.162.0.?) or else
throw it to the gateway to send the data on (ie internet).  Your IP
address on your workstation would be 198.162.0.2 (or 3 or 4... or 254).

Now we test that we can talk to the gateway using `ping 198.162.0.1`. 
This should respond quickly.

To get to the internet from a private network we have to masquerade 
(masquerade howto).  For debian there is a simple package that sets up a
reasonable box ipmasq on debian.  This does all the rules that set up a
fairly basic working set.  I have yet to be hacked and I was hacked
using redhat 6.2 using my own very very basic rules.  Waring ping does
not work from inside the network with ipmasq,  ping slug.org.au will
give me an IP address and then nothing until I control-c.  This is
normal.

Run you favourite browser and try to talk to the world.  Pick a site you
have never been to before to ensure you are not hitting your cache.  You
should be cooking with gas.

Hope this helps
KenF

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