Effects of Blocking GNN Ports

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Blocking these ports may affect:

  • Access to Microsoft Exchange servers over the Internet using MS Outlook (blocking these ports will not affect using MS Outlook over the local area network).
  • File/print sharing over the Internet.
  • Other programs or applications that are configured to use ports 135, 137, 138, 139 or 445 to communicate over the Internet.

See the following links for more information on ports used by Windows servers and services.