DNS lookup

The DNS lookup policy item provides the ability for WinGate to check whether the resolved IP address of a requested address record, is on an community based list of suspect or bad hostnames.

An example of one such community-based system is that offered by OpenDNS. This system normally requires setting your DNS resolver to point to their DNS servers. If your DNS resolver queries them for an address record that is in their list and relates to a blocked site, then DNS server will return the IP address of the server designated with issuing a blocked notification. Your browser therefore is redirected by DNS to a blocked notification page.

The DNS lookup policy item works by allowing you to specify which DNS list server the WinGate DNS resolver should check with. When the DNS lookup policy item is processed, a DNS query for the address (A) record is issued to the DNS server specified. If the result is returned in the time-out period, isn't an error result, and it matches the IP address specified in the Match field (i.e. the server designated to issue blocked notification) then the decision will evaluate to true.

You can use the Symbol Browser to insert the relevant data symbol (which represents the server portion of the hostname DNS lookup) in the Lookup field.

This policy item can be used to apply a SORBS style RBL operation to any parameter at any stage in the policy decision process. Server IPs can be checked as well as client IPs. With a custom DNS server, other fields (such as website) could be checked against an RBL of websites.

To use the DNS lookup policy item:

1. Select or create a policy to open a policy editor.
2. In the Items section of the policy editor toolbox, select a DNS lookup item and drag it on to the worksheet. This will open the DNS lookup properties.

   

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3. In the Lookup field, enter the server that is to be looked up. Alternatively use the Insert Symbol button to open the Symbol Browser and select the appropriate data to place in the field. In the example {{Request.Server}} has been used, so that every time the DNS lookup policy item is processed as part of the policy flow chart, the server portion of the current request will be looked up.
4. In the Use specific DNS server field, enter the IP address of the DNS list server that the lookup will be made to.
5. In the Match field, enter the IP address that the DNS list server would return if the resolved address is on the list (e.g. the web server that issues the blocked notifications).
6. Click OK to finish editing the DNS lookup decision and return to the worksheet.
7. The DNS lookup item will now blink, allowing you to give it a meaningful name so you can identify it easily in the policy evaluation flow.