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Microsoft's Netmeeting

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Running Microsoft's NetMeeting (to another host running Netmeeeting) to or from a network behind a Netopia that is running NAT can require some additional configuration to allow audio/video sessions.

The audio/video features of Microsoft's NetMeeting do not perform behind NAT. NetMeeting's a/v features places the source address in the data payload, as well as the header. NAT is not able to map incoming traffic with applications that use these types of embedded IP addresses because it does not examine that portion of the packet.

Due to the popularity of NetMeeting, current Netopia firmware has an ALG (application layer gateway) that modifies the source address and ports within the data payload enabling its use from behind NAT in a NetMeeting to NetMeeting type of connection.

Firmware Reference

v7.2 (and later) -- Netopia 3300 Series

Before you start

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Configuration

Network Configuration:

Example 1 :
Outbound sessions to remote hosts from workstations behind the Netopia.

Example 2 :
Inbound sessions to hosts behind a Netopia 3300 Series from remote workstations.

Please Note: The IP addresses used in the following examples are for illustrative purposes only.
Example 1 - Outbound Sessions to Remote Hosts
In this example you have a workstation or multiple workstations behind the Netopia initiating outbound sessions to remote hosts running NetMeeting.

Both of these workstations will be able to initiate outbound sessions to multiple remote hosts (however, not the same host concurrently). There is a built in ALG (application layer gateway) in the Netopia that will enable users on the internal network to place outbound calls to remote hosts without requiring any specific configuration. We have tested outbound sessions from NetMeeting to NetMeeting hosts only. Other variants may work but have not been tested.

Example 2 -Inbound Session to a Local Host
PLEASE NOTE: This configuration is applicable ONLY to the Netopia 3300 Series models.
In this example you have a remote workstation that needs to initiate an inbound session to a workstation behind the Netopia.

In order to allow an inbound session to a local host, you must create 4 Pinhole entries in the Netopia for ports 522, 1503, 1720 and 1731, all TCP protocol. You can follow the instructions in Quick Guide CQG_025 on creating a Pinhole entry. It's important to note that the ports must be each individual port, and not a range of ports, such as 1700-1800.

Once you have completed your changes, click on the symbol.
Click on Save and Restart.
At this point the router will reboot and when it comes back up it will be configured to use NetMeeting.

The Validation passed! and Ready to "Save and Restart"

Conclusion

For outbound Microsoft NetMeeting's Audio/Video sessions - no specific configuration is required on the Netopia. For inbound sessions - configuring the four Pinholes referenced above is necessary to allow remote workstations to initiate sessions to one workstation behind the Netopia. This technote addresses Microsoft NetMeeting only. Other audio/video applications may not function through Network Address Translation.