How to Establish NetMeeting Connections Through a Firewall (158623)
The information in this article applies to:
- Microsoft NetMeeting 2.11 for Windows NT 4.0
- Microsoft NetMeeting 2.1 for Windows NT 4.0
- Microsoft NetMeeting 2.11 for Windows 98
- Microsoft NetMeeting 2.1 for Windows 98
- Microsoft NetMeeting 3.01 for Windows 95
- Microsoft NetMeeting 2.11 for Windows 95
- Microsoft NetMeeting 2.1 for Windows 95
- Microsoft NetMeeting 2.0 for Windows 95
- Microsoft Windows 98
- Microsoft Windows 98 Second Edition
- Microsoft NetMeeting 3.01 for Windows 98
- Microsoft NetMeeting 3.01 for Windows NT 4.0
- Microsoft NetMeeting 3.01 for Windows 2000
This article was previously published under Q158623 SUMMARY
This article describes how to use Microsoft NetMeeting to establish connections over the Internet when you use a firewall to connect to the Internet.
MORE INFORMATION
When you use NetMeeting to establish a connection over the Internet,
NetMeeting uses several IP ports to communicate with other meeting
participants. If you use a firewall to connect to the Internet, the
firewall must be configured so that the ports used by NetMeeting are not
blocked.
NetMeeting uses the following Internet Protocol (IP) ports:
Port Purpose
-------------------------------------
389 Internet Locator Server [Transmission Control Protocol (TCP)]
522 User Location Server (TCP)
1503 T.120 (TCP)
1720 H.323 call setup (TCP)
1731 Audio call control (TCP)
Dynamic H.323 call control (TCP)
Dynamic H.323 streaming [Realtime Transport Protocol (RTP) over User Datagram Protocol (UDP)]
To establish outbound NetMeeting connections through a firewall, the
firewall must be configured to do the following:
- Pass through primary TCP connections on ports 522, 389, 1503,
1720 and 1731.
- Pass through secondary UDP connections on dynamically
assigned ports (1024-65535).
NOTE: Some firewalls are capable of passing through TCP
connections on specific ports, but are not capable of passing
through secondary UDP connections on dynamically assigned ports. When
you establish NetMeeting connections through these firewalls, you
are unable to use the audio features of NetMeeting.
In addition, some firewalls are capable of passing through TCP
connections on specific ports and secondary UDP connections on
dynamically assigned ports, but are not capable of virtualizing
an arbitrary number of internal IP addresses, or are not capable of
doing so dynamically. With these firewalls, you are able to
establish NetMeeting connections from computers inside the firewall
to computers outside the firewall and you are able to use the
audio features of NetMeeting, but you are unable to
establish connections from computers outside the firewall to
computers inside the firewall.
The H.323 call setup protocol (over port 1720) dynamically negotiates
a TCP port for use by the H.323 call control protocol. Also, both the
audio call control protocol (over port 1731) and the H.323 call
setup protocol (over port 1720) dynamically negotiate User
Datagram Protocol (UDP) ports for use by the H.323 streaming
protocol, called the real time protocol (RTP). In NetMeeting, two
ports are determined on each side of the firewall for audio and
video streaming. These dynamically negotiated ports are
selected arbitrarily from all ports that can be assigned
dynamically.
NetMeeting directory services require either port 389 or port
522, depending on the type of server you are using. Internet
Locator Servers (ILSs), which support the lightweight directory
access protocol (LDAP) for NetMeeting 2.0 or later, require port 389. User
Location Servers (ULSs), developed for NetMeeting 1.0, require port 522.
Modification Type: | Minor | Last Reviewed: | 12/16/2004 |
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Keywords: | KB158623 |
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