Mapping Services - Mapped links

Mapped Links are perhaps the simplest level of gatewaying.

Mapping proxies are not as flexible as the other proxies are. This is because they are a simple pipe-through of the data. For this reason you need to specify a remote host to connect to. Think of a Mapped Link as a patch cord or pipe. You are effectively patching machines through to remote machines, on specified ports. You can specify a remote host and port number for each individual LAN workstation, or a default remote host and port, which would be used if the machine connecting to the gateway did not have a specific map entry. It is important to remember that mapped links are usable on any TCP/IP network, be it the Internet, a Company WAN or a home/office LAN.

Example: To use Internet news:

News uses port 119. WinGate does not have a news proxy, so you have to use a mapped link. You have to know what news server you want to use, and what port it is on. Say you choose news.cnn.com also on port 119.

Setup a mapped link on port 119 with a default host of news.cnn.com, on port 119 and ensure that it is enabled.

When you want your news program to get your daily newsgroups, you ask it to connect to ‘wingate’, not news.cnn.com, because WinGate has now become a connection to your news server: news.cnn.com on port 119.

If you access the port for news, you will be communicating with the news server via WinGate. The News program doesn’t know or need to know this, all it cares is that WinGate appears to be a news server. WinGate does not even know what protocol is running over the link, only the client and server need to know this.

The ports used for mapping sometimes want to be used in different ways by different people. For this reason, WinGate 2 has a Mapping by user or location. E.g. some users may wish to use a certain news server, and others may wish to use another. If this is the case, you need to add specific mappings. To add a mapping, you choose the mappings tab, add a mapping, and enter the values for the server and port and the conditions under which (i.e for who / where from) WinGate will use this new server and port rather than the default.

Timeouts:

For TCP based services (i.e anything except DNS, XDMA, and UDP Mappings) the session timeouts are really only there as a safeguard against problems. In the normal operation of a session, it will terminate when it has done its stuff. However, sometimes connections can be left open when nothing is happening, and so the timeouts are there to terminate those sessions, so that they don't do things like holding the modem up.

For UDP-based (UDP Mappings, DNS etc) sessions however, the timeout is the ONLY way a session will ever terminate, as there is no connect and close for a UDP socket, so no indication is made of when a session is completed.

Adding Mapping services