A 'RAT' is not always destructive software, it is used in TeamViewer. Team viewer uses the same reverse connections as a rat like DarkComet or BlackShades. A RAT Works by using a 'Reverse connection' to connect to your friends via Opening some sort of 'Gate' Theses gates can be in the form or 'Hamachi' Or Some sort of program that connects your home network(LAN) Together, this is usally done VIA Port Fowarding but can be achieved with ProXPN and some people use this. In this mode of operation remote computer(s) acts as the "Host" for the RAT software, for the "client" remote administrator to control. RATs that are utilized with reverse connection have the following operational advantages.
Outgoing connections are generally perceived as less threatening to the remote "host" user, as it is the remote user who activates the download of the remote administration tool software. This procedure usually allows the software tool to avoid being blocked by a firewall, such as used in a router device.
Since the remote "host" computer itself is connecting to the remote administrator, it will not be necessary for the remote administrator to know the remote "host" computers IP address to send the software tool.
The remote administration tool also allows for mass-distribution across a computer network if this facility is required.