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Firewalls

If your source and target are on opposite sides of a firewall, you will need to configure your hardware to accommodate communications. You must have the hardware already in place and know how to configure the hardware ports. If you do not, see the reference manual for your hardware.

• Double-Take Availability ports—Ports 6320 and 6325 are used for Double-Take Availability communications and must be open on your firewall. Also, Double-Take Availability uses ICMP pings, by default, to monitor the source for failover. You should configure your hardware to allow ICMP pings between the source and target. If you cannot, you will have to configure Double-Take Availability to monitor for a failure using the Double-Take service. See the failover instructions for your specific workload type.
• Microsoft Windows ports—Double-Take Availability protection uses WMI (Windows Management Instrumentation) which uses RPC (Remote Procedure Call). By default, RPC will use ports at random above 1024, and these ports must be open on your firewall. RPC ports can be configured to a specific range by specific registry changes and a reboot. See the Microsoft Knowledge Base article 154596 for instructions.
• Virtual workload protections—If you are protecting virtual machine, Double-Take Availability will also rely on other Microsoft Windows ports which must be open on your firewall. Check your Microsoft documentation if you need to modify these ports.
• Microsoft File Share uses ports 135 through 139 for TCP and UDP communications.
• Microsoft Directory uses port 445 for TCP and UDP communications.

You need to configure your hardware so that the Double-Take Availability ports and Microsoft Windows ports are open. Since communication occurs bidirectionally, make sure you configure both incoming and outgoing traffic.

There are many types of hardware on the market, and each can be configured differently. See your hardware reference manual for instructions on setting up your particular router.