Version 4.0

User's Guide

4. Configuring NetProxy Services

4.11. Mapped Ports

NetProxy allows mapping of both TCP and UDP ports to specific destinations. Mapped ports facilitate the use of many Internet protocols through NetProxy, including (but not limited to):-

• Simple Mail Transfer Protocol (SMTP) for sending e-mail
• Network News Transfer Protocol (NNTP) for reading and posting USENET news
• Mirabilis ICQ for communicating with remote users
• Network Time Protocol (NTP) for synchronising PC clocks with a central resource on the Internet

Mapped ports are also useful for configuring video conferencing and collaboration programs, as well as providing a method for making nominated servers on your network available to the Internet at large (WWW, FTP or SMTP servers for example).

The configuration dialog for adding and editing mapped ports appears below. More information on each setting is given below the picture and continues on the next page. To display specific help on each of the settings, click the Windows 'context help' icon at the top of the dialog box in NetProxy, then select the item you wish to learn more about.

Description
This is a textual description of the service provided by the mapped port. It is intended to provide a useful reference to system administrators.

Local Port
Specifies which TCP or UDP port on the NetProxy PC is to be mapped. Ports that are in use by another application or service cannot be mapped. Port number can be in the range 1 - 65535.

Bind to Interface
Allows you to select a specific IP interface that NetProxy should bind the service to. Any connection attempts not received on this IP address will be blocked by the operating system before they even reach NetProxy's firewall.

For example, if the IP address assigned to your local network card is selected, any connections arriving via your external IP interface (the one belonging to your dialup or ADSL connection) will be rejected by Windows.

IP Protocol
Specifies which protocol (UDP or TCP) this port mapping is for. TCP a reliable streaming protocol, used for the majority of applications including mail and news. UDP is a datagram-based protocol that is often used for 'real-time' media such as video and audio.

Default host and port
Specifies the default host and port number that NetProxy maps connections to for this mapping. If there are no exceptions listed that match the IP address of the connecting machine, NetProxy maps the connection to the default host.

Exceptions list
Shows a list of exceptions to the 'default' destination host and port. If the IP address of the connecting machine matches one of exceptions, the specified host is connected to instead of the default. If the incoming connection matches more than one exception rule, the 'best match' is used (i.e. the exception with the most bits specified after the slash).

Add Exception
Displays a dialog box that allows you to add a new exception rule for the mapped port.

Edit Exception
Displays a dialog box that allows you to edit the currently selected exception rule.

Remove Exception
Removes the currently selected exception rule.

Allow Global Access
When this option is enabled the incoming firewall rules are ignored for the specified mapped port, thus providing a simple means of running a world-accessible server such as a public WWW, FTP or SMTP server on a machine situated behind NetProxy's firewall.

Contents Page or Continue in Sequence