Static and Dynamic Port Applications

Static port applications run on known or static ports. Examples include IMAP and POP servers, Telnet daemons, and jCIFS. For static port applications, the Netlet rule includes the destination server port so that requests can be routed directly to their destinations.

Dynamic applications agree upon a port for communication as part of the handshake. You can include the destination server port as part of the Netlet rule. The Netlet needs to understand the protocol and examine the data to find the port being used between the client and the server. FTP is a dynamic port application. In FTP, the port for actual data transfer between the client and server is specified through the PORT command. In this case, the Netlet parses the traffic to obtain the data channel port dynamically.

Currently, FTP and Microsoft Exchange are the only dynamic port applications that Portal Server supports.

Although Microsoft Exchange 2000 is supported with Netlet, the following constraints apply:

• For Portal Server versions before 6.3:

  • You must configure Exchange to use STATIC ports.

  • Netlet does not work with Windows 2000 and XP because Windows 2000 and XP clients reserve the Exchange port (port 135) for the RPC Portmapper, which Active Directory uses. Previous versions of Windows did not reserve this port. Because the port is reserved, you cannot assign Netlet to it, and thus the port cannot provide the necessary tunneling.

  • The Outlook 2000 client has the limitation that it does not enable you to change the port on which you want to connect to the Exchange server.

• For Portal Server 6.3 and later versions, Proxylet technology was introduced for use with OWA and Sun Java Enterprise Server, Portal Server Secure Remote Access deployments issues. Portal Server Administrators should consider this technology for a better user experience.