Malicious-Website Blocking (DNS Redirection)

You are protected from from connecting to websites known to be malicious—websites that attempt to steal your personal information or infect your device with malware—when you are on most U-M networks on the Ann Arbor campus, including the MWireless WiFi network and wired ethernet connections in most U-M buildings associated with the Ann Arbor campus.

This protection does not extend to Michigan Medicine networks, U-M networks using a unit-provided DNS service, and U-M networks in units that request DNS redirection not be implemented (typically networks used for specialized research).

Domain Name Service (DNS) redirection or filtering is an additional tool to protect you from malicious websites. DNS redirection works with your web browser to:

  • Check websites you try to visit against a denylist of known malware and phishing sites.
  • Block access to sites on the list.

What Happens When a Site is Blocked

If you try to visit a website that has been identified as malicious, you will be redirected to a warning page: Warning: Malicious Website Blocked.

Note that the redirection affects all connections to hosts on the malicious list, including those via SSH, SFTP, and more. These connections may fail without an error message. Connection problems from U-M networks can be reported to the ITS Service Center.

About the DenyList and Filters

  • IA staff use a threat intelligence management application to combine regularly updated data feeds from multiple trusted sources, including some of our peer institutions and the Research and Education Networking Information Sharing and Analysis Center (REN-ISAC). They also include threats they have identified.
  • Only websites that contain phishing and malware are identified as malicious and added to the denylist. Sites are not blocked based on website content.
  • Sites (hosts) on the list are identified by domain name.
  • The ITS Domain Name System (DNS), which is used in routing traffic on most UM-Ann Arbor networks, is used in concert with the list of malicious sites to block users from reaching those sites.
  • IA maintains an AllowList of U-M domains based on a list the 10,000 most visited sites. Connections to these sites go through automatically and are not checked against the list of malicious sites.

Respecting Your Privacy

DNS redirection blocks access to sites based on their reputation. It is fully automated and does not collect, examine, or track information about individual users or site content.

  • No identification of individual users.
  • No collection or tracking of content sent between users and sites.