Figure1. Before connecting Computer office
Rev. 0.1
5/31/2007
1. What's Trate
2. When do I need Trate
3. Where can I find Trate
4. How to use Trate with WinSCP+
Trate is a free software to support Peer-to-Peer communication across Network Address Translator (NAT).Trate allows other applications - almost all applications(BitTorrent,Web server etc) - to automatically create dynamic connections between two or more peers behind two or more separate NATs and firewalls.
That means machines behind a NATed firewall (e.g. An enterprise firewall, or a home router) can connect to each other through the help of Trate. More specificly, it can accelerate your BT downloads, allow you running your Web or FTP site behind a firewall with a private IP address, or help any application which needs to listen to a port.
Refer to Quick Start Guide for Trate for more infomation.
WinSCP+ do not support peer to peer communication across NAT, therefore if one or both of your computers are behind NAT, you'll need Trate to help you get through.
You can download install package of Trate from sourceforge.net.
(1) Install WinSCP+ on your computers.
(2) Install Trate on all the computers on which you have installed WinSCP+. Trate will start automatically each time you start your computer.
When started, Trate will registrate the host machine on the Trate Server, Trate Server will record the machine's Public IP and port number.
For most of the time, Trate does nothing except listening to the network traffic on local machine. When it find an application fails to receive TCP response form its remote target, Trate will inquery the Trate Server for possible record about the remote target. If the Trate Server keep a record about the remote target, Trate will use the information to setup a connection to the remote target and help the local application to get through.
(3) Start WinSCP+ and use it as usual. If WinSCP+ is behind NAT and cannot receive TCP response from other machines, Trate will find the situation and inquery the Trate Server for infomation about the remote machine (Because all the machines is running Trate, so the Trate Server keep their records), and use the information to setup a connection to the remote machine.
(4) The following pictures shows the procedure of using Trate with WinSCP+. The two client computers running WinSCP+ are both under NAT networks.
Figure1. Before connecting Computer office
Figure 1 shows the two computers in the virtual network is "office" (remote) and "home" (local). Before "home" tries to connect "office" the Trate icon is yellow, which means no connection is established yet. When user clicks on the "Browse" label, the local computer will try to connect remote computer. Because they're behind NAT networks, the first attempts will fail, as shown in figure 2.
Figure 2. Connection timed out in the first attempts
Trate listens to the network activities on the local machine and sets up a timer for each program which initiate a TCP connection, if the program failed to receive TCP response in a set period, e.g. 3 mins, Trate will tries to established a connection for it. So, now Trate takes over the connection task and consults the Trate Server for infomation about client "office". Because "office" and "home" both installed Trate, so they left their records on Trate Server. Trate then uses the information to established a connection for "office" and "home". The Trate icon will turn to green when the connection is established successfully. As shown in figure 3.
Figure 3. Trate established a connection
Now, "office" and "home" can use this connection to communicate with each other. As shown in figure 4:
Figure 4. WinSCP+ connected behind NAT