----- Original Message -----
From: "Jill Thomson" <jthomson@...>
On Behalf of?: > Peter Lawson
> One of our clients has a device called an Internet Gateway. It seems to be
> a type of hub, sitting in the middle of the TCP/IP network, which enables
> any of the computers to dial out to the Service Provider.
Actually this device dials the service provider itself. Typically such a
device then uses Source Network Address Translation (S-NAT) to make IP
connections to hosts on the Internet on behalf of hosts on the LAN. It
effectively hides the local hosts from the Internet so if you watch the
traffic from the Internet side it looks like one device doing lots of work.
It keeps track of all the internal clients and their Internet connections
and translates incoming traffic so that it ends up with the correct internal
host.
> It has an I P
> address of its own - but it automatically assigns I P addresses to all
> the computers.
It includes a Dynamic Host Configuration Protocol (DHCP) server which
allocates IP addresses and other details for client machines which include a
DHCP client (Modern Macs, Win9*, WinNT/2K are all candidates).
This device probably also configures itself as the default gateway so that
clients know they can route traffic to remote networks through it and as the
primamry Domain Name Server (DNS) for the network.
Unfortunately these devices do not usually provide a full featured DNS but
instead just forward requests to a DNS on the Internet so it is not posible
to configure it such that clients on the LAN can resolve local (internal)
names by using DNS.
> This would seem to create problems for Interbase, which I understand can
> only function over a TCP/IP network if a permanent relationship is
> established between computers and I P addresses and this is recorded in
the
> hosts file which must reside on each computer.
These devices are usually configurable using a web browser (if not you can
telnet to then or use some software on a client PC to configure them).
Using one of the above methods you can reserve an IP address within the
nework that has been configured (eg 192.168.0.100 from 192.158.0.* or
10.0.0.100 from 10.0.0.* etc) so that it will never be provided to a client
using DHCP.
You shuld then use this IP address to statically configure the IP of the IB
server.
Now you can do one of the following to ensure that clients can find your
server.
a) Use the IP address
b) Set up hosts files on each client machine and use the assigned name
c) Set up a DNS on the local network to handle this task for internal
machines, set if up to forward external requests to the device or an
external DNS. Set up the device to tell clients about the new DNS server on
the network when it configures then using DHCP.
Many other options - going off topic, if there is a WinNT server or a Linux
server running Samba on the network Windows Internet Naming Service (WINS)
could be an option for local name resolution.