UserGate DHCP Server

This module is designed for setting the DHCP (Dynamic Host Configuration Protocol). The DHCP service provides centralized management of IP addresses and standard TCP/IP parameters. If you have a DHCP server set up on your network, you can assign dynamic IP addresses for any computer network interface. A DHCP server also automates the management of other TCP/IP parameters.

When setting up a new DHCP server, it is automatically provided with parameters optimal for the current network environment.

DHCP server settings

DHCP management is done by clicking the Add button in the UserGate Control Panel. ( Illustration).

Select the interface, which should be used for passing data to DHCP clients. ( Illustration).

Then you should set up the IP Range in which DHCP should assign client IP addresses when leasing and reserving, as well as the subnet mask. ( Illustration).

Note: If you already have a DHCP server working on your network, be sure that this new IP range doesn't conflict (intersect) with the range(s) used by your other DHCP server(s).

Using the "Exclusions" button, specify the IP address or IP range you want to exclude from being assigned by the DHCP server. ( Illustration).

Specify the lease time for the IP addresses.

Note: If you specify too long a lease time, it may decrease DHCP efficiency and could result in running out of available IP addresses. This is especially important when there are many users that are not permanent clients. For most networks, the optimum lease time is 1 to 3 days.

As your default gateway, specify the IP address of the computer working as a proxy, the one that has UserGate running on it.

If you use DNS and WINS on your network, specify the IP addresses of the DNS server, the WINS server and the parent domain name.

The purpose of reserving is so a specific PC can have a particular IP address. It is based on the network interface's MAC address.

To add reserving, press the icon that looks like this: Enter the IP address of the computer and press the MAC button to automatically get a MAC address of the specified IP. ( Illustration).

Web Proxy Automatic discovery (WPAD)

Usergate DHCP server supports Web Proxy Auto Discovery (WPAD) technology which helps to configure network hosts to work through Usergate proxies. This function could be enabled through “Proxy auto config” option in DHCP server settings dialog ( Illustration).

To work with WPAD you should:

- Edit wpad.dat file, located in %Usergate%\wwwroot folder, and specify correct proxy parameters (IP address: port) for each protocol: HTTP, HTTPS, FTP etc.
- Enable proxy auto discovery in user’s web browser ( Illustration).

Attention! Each web-browser has its own peculiarities of WPAD implementation. For example, Mozilla Firefox prefers WPAD through DNS.

In wpad.dat file you should specify HTTP response header of Usergate Web – server and proxy servers parameters using JavaScript:

HTTP/1.1 200 OK
Server: Usergate 4.3
Content-Length: 405
Content-Type: application/x-ns-proxy-autoconfig

function FindProxyForURL(url, host)
   if (isInNet(host, "", "")) {
	return "DIRECT";
   } else {
	if (shExpMatch(url, "http:*")) 
		 return "PROXY";
	if (shExpMatch(url, "https:*"))
		 return "PROXY";
	if (shExpMatch(url, "ftp:*"))
		 return "PROXY";
	return "DIRECT";
In order to simplify the process of WPAD configuration there is a template wpad.dat file in %Usergate%\wwwroot folder. You should only specify correct IP addresses and ports.

Import DHCP server settings

Usergate DHCP server can use Windows DHCP server settings. To transfer these settings you should dump Windows DHCP server settings into a text file. To do this open command console on a Windows DHCP server (Fig. 5) and run a command: netsh dhcp server [IP] > c:\dhcp.txt ( Illustration).

In Usergate DHCP server settings dialog press Import button and select a corresponding file ( Illustration).

Automatic user creation

After creating and configuring Usergate DHCP server the issued IP addresses will be displayed on “Services – DHCP” page. The issued IP addresses can be used to automatically create a corresponding user in Usergate. To do this, highlight the desired IP address from the list and select Add user in context menu. If the user with this IP or MAC address already exists in Usergate, you will be asked to edit an existing user. ( Illustration).

Furthermore, issued IP address can be released by pressing icon. The need for releasing of the issued IP address can occur, for example, if the computer is no longer present in the LAN