Internal & External IP addresses on single NICs

[Sfixphdi]

As I begin most of my posts, forgive me if this topic was already covered in detail. I did a search and was not able to find a specific answer to help me, so I thought I would try a new thread. I am attempting to simplify a complex setup I had on my network. Everything worked, but it was very inefficient and slow. I do not use a standalone router, as I have several static IP addresses from my ISP that I assign to my machines. Let's say I have the public addresses 99.99.99.101 and 99.99.99.102 assigned to my machines. I also use a network printer, and for awhile I was using the IXP protocol to print and to file share between the computers. That protocol was very cumbersome and slow, and I wanted a way to go back to TCP. So, I thought why not just bind some internal IP addresses to the NICs on the machines and go with that! So let's say I have 192.168.1.101 and 192.168.1.102 respectively on the machines I mentioned above. The printer is 192.168.1.103 and both machines can ping and print no problem. But they cannot file share over the internal IPs!

Server: 99.99.99.101/255.255.255.0 Gateway 99.99.99.1
192.168.1.101/255.255.255.0 No Gateway

Workstation: 99.99.99.102/255.255.255.0 Gateway 99.99.99.1
192.168.1.102/255.255.255.0 No Gateway

I have a feeling it is a gateway issue, although when I tried binding an internal gateway to the nics as well, I was unable to get out to the internet at all. If I try to file share between the machines via the external IP addresses, it works fine. But remember, I can print via the internal IP addresses, so I'm completely stumped here. Oh yes, the server is Windows 2000 Server and the workstation is Windows 2000 Pro. Thanks in advance!

 

[cyberspace]

How are you able to assign two addresses to one NIC?

Personally I would totally change the setup of the network and drop in a router & switch unit. What internet connection do you have?

This will also give you an extra layer of security - as it stands, you are assigning external public addresses directly to a NIC of a Server and a Workstation, with no mention of a firewall, this presents a fairly large security risk!

The router could take the public address, then you could assign purely private addresses to the NICs. It doesn't make sense to want to use public and private addresses on the same NIC.

The file sharing issue could be a number of things, such as a netbios issue, or a windows firewall issue.

What did you try to use as an internal gateway?

'When all else fails.......read the manual'

 

[Sfixphdi]

Assigning multiple addresses to single NICs is easy and is well documented on the internet. That is not the issue. I also have adequate firewall security without a router, and would prefer not to have my machines behind routers for a variety of reasons. The issue I cannot solve is why the machines will see each other using the external IP address and not the internal IP addresses. I'm thinking it has to be a gateway issue, but I'm just not sure exactly what I need to do. I tried using the server address 192.168.1.101 as the gateway address, and that didn't work. I suppose there must be a way to make a Windows 2000 server function as a gateway...

 

[pansophic]

The problem may actually have more to do with DNS than routing (gateways). If the machines are attempting to do any form of name resolution with the 192.168.1.x address space and you are pointed to Internet DNS servers, then that could cause an issue. The only time that a gateway is even needed is if you are trying to connect from one subnet to another. If all of the addresses are 192.168.1.x and you are using a 255.255.255.0 netmask then the gateway will never even come up. You can leave it blank and it won't change anything. Of course you have resolvable addresses too, so that is not really an option.

Have you tried putting the 192.168.1.x addresses in the hosts tables? Put all three addresses in all three hosts and see if that resolves the issue. If it does, you may want to try something like a local caching DNS server that also has your internal address space defined.


pansophic

 

[cyberspace]

Well I guess you learn something new every day, I didn't realise you could even do that. Hope you get it sorted.

'When all else fails.......read the manual'