Enter Gateway Host Data

Gateway host is the computer on which the Trilent Mail Proxy is installed. It is a gateway through which your internal network is connected to the Internet. Gateway hosts must have at least two interfaces. One interface (the inside interface) is connected to the inside network while the other (the outside interface) is connected to the Internet. To learn more about gateways and interfaces, refer to the Application Note section.

Click on the "Gateway Host" tab of the control applet. The screen will look like this:

The setup program automatically configures the proxy during installation by entering the correct IP addresses for the inside and outside interfaces of your computer. (Learn more about IP addresses here.) For computers with a single network interface, the Setup enters the data for Single-Computer Operation. We recommend you review the configuration before the first use. If these fields are left blank, it means the setup could not reliably determine the correct interface addresses. You have to enter the IP addresses manually, as show below.

The best way to obtain address information is to run the ipconfig program. Click on "Start" menu, click on "Run.." and type cmd. Click on "OK" button. The black command screen opens. Type ipconfig at the prompt and hit "Enter". The program output may look like this:

Windows 2000 IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 192.168.0.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :

Ethernet adapter DSL Connection:

Connection-specific DNS Suffix . : example.com
IP Address. . . . . . . . . . . . : 139.12.0.17
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 139.12.0.1

In this example, our gateway host has two interfaces. The inside (internal LAN) interface has the address 192.168.0.1. The outside interface (DSL connection to the Internet) has the address 139.12.0.17. The outside interface usually has a non-empty "Default Gateway" entry.

Limiting Access to the Mail Proxy

For added security, you can limit access to the mail service to specific computers on your network. Enter the IP addresses of computers permitted to connect to the mail proxy (and through the proxy to access mail servers on the Internet) in the field "Permit client connections from these addresses:". (Learn more about IP addresses here.)

You can enter a single IP address (such as 192.168.0.3), an address range (such as 192.168.0.2-5, which includes addresses from 192.168.0.2 to 192.168.0.5), or a network address. Network addresses usually have zeros in right-most positions. For example, network address 192.168.1.0 includes addresses 192.168.1.1 through 192.168.1.255, while network address 192.168.0.0 includes addresses 192.168.0.1 through 192.168.255.255.

Trilent Mail Proxy also supports network masks. Network mask has the following format: 192.168.0.0/24 . The number after the slash represents the number of bits (possible value: 0 to 32) of the network part of the address. (Each of the four dot-separated fields of an IP address is 8 bit long, for a total of 32 bits). For example, the address above has the network part that is 24-bit (or 3-field) long. The remaining (fourth) field represents host addresses. Therefore, the network address 192.168.0.0/24 contains addresses 192.168.0.1 through 192.168.0.255. Please note that without the network mask, the same network address 192.168.0.0 would include addresses 192.168.0.1 through 192.168.255.255, a much larger range. As you can see, the explicit network mask takes precedence over the number or right-most zeros in the address.

Also note that this address would be appropriate to use in our example network.

Shortcuts: You can omit one or more of the right-most zeros in a network address. You can also replace one right-most zero with a star (*). For example, the following addresses are equivalent:

10.0.0.0 10.0.0 10.0 10 10.0.0.* 10.0.* 10.*

The network address * (star) or 0 matches everything, while an empty entry matches nothing (no client computer is permitted access to the mail proxy). The setup program inserts the star into this field. That permits access to the proxy from everybody.

Tip: Do not change this initial setting until after you have succesfully configured and started the proxy for the first time. Many questions to our technical support originate from this area. Multiple Nets: You can enter up to five comma-separated network addresses in the format described above. No spaces are allowed. For example, this is a valid entry:

192.168.0.0/24,127.*,10.1.125.17-26,10.1.125.29,172

A client computer with IP address matching any of the entries above will be permitted to connect to the proxy.