How to Configure Neverfail Engine to Use a Different Principal (Public) IP Address

How to Configure Neverfail Engine to Use a Different Principal (Public) IP Address



This Knowledgebase article provides information about how to change the Neverfail Engine principal (public) IP address.


More Information

The principal (public) IP address are specified during installation. However, you can change the principal (public) IP address settings in a LAN topology using the Server Configuration Wizard after installation.


To change the principal (public) IP address settings on a Neverfail server, follow the steps below:

  1. Stop Neverfail Engine leaving the protected application running.
  2. From the Windows Network and Sharing console, change the IP on the network card used for public (production) connection. 
  3. Open the Neverfail Server Configuration Wizard by navigating to Start -> Programs -> Neverfail > Configure Server then select the Public tab.mceclip0.png
  4. You can configure your server with one or more principal (public) IP addresses.  These are the addresses by which clients machines will connect to the protected application. Typically, there will only be one public IP address. On the passive server, all traffic to and from the principal (public) IP addresses is blocked by the Neverfail Packet Filter in order to avoid an IP and/or Name conflict with the Active server. When the role of the servers is switched, the IP filtering mode also switches, so client systems always connect to the principal (public) IP addresses on whichever server is currently active. When the Neverfail service is shutdown, the filtering remains in place so you do not get IP/Name conflicts between the 2 servers. In the principal (public) IP address table, you list all of the addresses that will be used as principal (public) IP addresses. Add a new row by clicking the 'Add Row' icon to the left of the table and delete unwanted rows by clicking the 'Delete Row' icon. Clicking the 'Trash can' icon will delete the entire contents of the table. Select the Reset button to return to the original settings if required. An address should not appear more than once, and should not be the same as any of the IP addresses listed in the Channel panel.
  5. Once you have made your changes click Finish to save the new settings.

Networking Hint

The principal (public) addresses configured for the Primary and the Secondary server must be identical. Any other 'private' addresses configured for Primary or Secondary network cards must be different.  If you configure your network cards with a 'private' address in the same subnet as any of the public addresses, check the routing tables to ensure the subnet is reachable when the principal (public) IP traffic is blocked. Use the route print command to list the routing tables.  If the public address appears as the Gateway for its subnet, then you may not be able to use other addresses on the same subnet when the IP traffic to the public address is blocked e.g you may get no response when you ping the 'private' address from another machine.  To fix this, reorder the IP addresses using the system's Network Connections window. The IP address at the top of the list is the one through which all traffic is routed.


Applies To

All Versions


Related Information

Knowledgebase article #492 - How to change the Neverfail Channel IP address(es), When Neverfail is Already Installed on the Pair