Network IP addresses

[UkMister]

I'm not sure this is the right place to post but it is to do with security because I'm looking to install some mail security software and it needs to be on a separate machine to our mail server.

I'm trying to determine the ip addresses used in each stage of our network but I'm having problems when it comes to the router and firewall.

We have our network, around 70 clients and a server that has exchange on it. This server has 2 nics, inside and outside. These ip addresses I know. The exchange server (outside) is connected to the firewall. I know the ip address for this.

Now I get a bit confused at the other side of the firewall, where it is connected to the router. I can't seem to find what ip addresses the router or this side of the firewall uses. Is there an inside and outside address? Does it use default gateways?

I'm not very familiar with routers and firewalls so any help or any pointers in the right direction would be great.

 

[vop]

Do you know how to log into your router? On mine, I simply type 192.168.1.1 into a browser and enter password.

Go to the 'port-setup' section (Edit>Find) of the following link if you require login assistance and default password for your particular router:

http://www.pctechpaltalk.net/.

On a Linksys there is a status tab that brings up WAN particulars (intermediate NAT parameters) such as WAN IP and WAN Default Gateway (10.x.x.x) which interfaces with my external IP (142.x.x.x).

 

[rn4it]

What kind of Firewall are you running? Can it do NAT (Network Address Translation). The reason I ask, is from what you've described above your server has 1 NIC with a real world IP and 1 NIC with your private IP. If this is true, then there is nothing protecting your server, in which case you might as well remove the internal NIC and just create a rule that allows your Internal Network access it. If your FW can do NAT then remove the NIC that has External IP and then NAT it through your FW, using the external IP. At least this way you can only allow ports to that server that it needs. (ie smtp for email server, or 80,443 for webservers.
[cheer]