Configuring DNS Filter

Overview

DNS Filter enables the admin to intercept and block connections involving specified domains based on DNS resolution.

DNS Filter differs from Web Filter in two ways:

1. Its block occurs "before" Web Filter would see the session in question. This has the effect of preventing Web Filter from seeing and acting on the session: DNS Filter supersedes any settings in Web Filter for the specified domain.
2. It can act on traffic other than HTTP/S traffic. For example, if an application would attempt to connect to a blocked domain using a protocol other than HTTPS, DNS Filter will block that connection.

Configuring the DNS Filter

These options are found in Settings > Services > DNS Filter.

The DNS Filter Enabled toggle determines whether DNS traffic is captured and scanned.

Blocking specific sites & domains

Block Domains enables the admin to specify sites which are blocked at the time a DNS query resolves their domain name. 

1. Click Add Domain to begin adding a new domain
2. Enter the domain/URL in the Enter Domain Name field. For example, to block Amazon, enter "amazon.com" in this field.
   • The exact match checkbox determines whether the lookup must match exactly. If this option is disabled, entries with URI information (anything after the .com/ part of a URL) will also be matched.
3. Select the desired action to take when this domain is resolved:
   • Block blocks the domain, preventing access to the site
   • Flag allows the session, but creates a "flag" on the session
     When Flag is selected, Log is automatically selected as well and cannot be disabled.
   • Log logs the event in DNS Filter reports
4. Set a Description so you know what the rule is intended to accomplish
5. Click OK to create the rule
6. When you have finished adding a domain(s), click Save to save your changes

Managing blocked domains

All blocked domains are listed on the main page in table format. The Filter Domains field enables you to search the list of blocked domains by hiding all entries which do not match your text entry.

To edit a domain, click the pencil icon at the right-hand side of the entry.

To delete a domain from the list, click the trash can icon at the right-hand side.