[AccessD] Hamachi as service

Ok, we'll check it out tomorrow, they were all emailing fine when we set
them up.  Who knows.

Drew

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Stuart
McLachlan
Sent: Sunday, June 01, 2008 9:35 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Hamachi as service

You're mixing up and combining two things there, DHCP and NAT.
NAT doesn't assign addresses. DHCP (Dynamic Host Configuration Protocol)
does that.

Each computer in your private network has to have a separate IP Address.
That address 
can either be fixed (you enter it into the network configuration window)
or assigned from a 
pool by a DHCP server each time the computer is switched on and connects
to your local 
network.

Your private network uses one of three "non-routable" address ranges.  
(10.*.*.* , 172.16.*.*.  - 172.31.*.*  or 192.168.*.*)

Your Internet Router has one address in this range on the "inside"  and
one or more 
separate public, "routable" addresses on the outside. 

Assume your Router's internal address is 192.168.1.254.

Your workstation will be configured with  an address such as
192.168.1.3, a mask of 
255.255.255.0  and a Gateway of 192.168.1.254.

Because of the mask, if you try to communicate with any computer in the
192.168.1.* range, 
you will talk directly to that machine. 

If you try to access any address outside of that range, the packets will
be sent to the 
Gateway/Router on 192.168.1.254.  The router will then send your packets
to the destination 
computer.  That destination computer will then send it's reply back to
the external address of 
the router. Once the router receives the reply back it will send it on
to your computer 
192.168.1.3.   Note that the destination computer doesn't know that the
request has come 
from your workstation at 192.168.1.3, it thinks it has come from the
external address of your 
router.

NAT is the process of the router accepting packets from you, translating
your network 
address into the routers own external address and translating it's
external address back to 
your network address on the reply packets.  The NAT software basically
keeps track of all of 
the outbound  packets  from each of the computers on your internal
network and redirect  
incoming packets to the correct originator.   

This can  only work for messages which originate within your network.
If you have a 
machine on your network which *listens* for requests originating from
the outside, such as 
an FTP server, Web server, SMTP mail server or Remote Desktop,  you have
to configure 
your NAT to translate all such incoming requests to the specific
machine - so-called "Port 
Forwarding".

In this case, you can't just use an assigned DNS assigned address for
the workstation, it 
must be configured so that it always uses the same address, and you
can't use the same 
Port for more than one machine so in the case of Remote Desktop, you
need to use a 
different port for each workstation.

-- 
Stuart



On 1 Jun 2008 at 21:48, jwcolby wrote:

> As you probably know, NAT (Network Address Translation) 
> causes each computer within your network to be assigned an 
> IP Address, usually in the range of 192.168.x.x.  The 
> problem with NAT addresses is that they "interfere" with 
> remote desktop, particularly coming in from the outside 
> through a router.  By default, Remote Desktop uses port 3398 
> as the remote access port.  In order to come in through the 
> router, each machine has to be assigned a static IP address 
> by the router, and then port forwarding turned on, and 
> "ports" forwarded to specific IP addresses.  It just becomes 
> messy.
> 

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