Remote Access

Modern computing requires the use of a variety of resources located on different machines in widely separated locations. You are familiar with the world wide web, which allows us to obtain information from other machines. However, mathematicians frequently need to create and delete files on other machines, or even to use their processing power. There are many tools to allow us to do this. WinSCP is a Windows SFTP/SSH client, used to replace old File Transfer Protocol clients. You can obtain this client freely at It should also already be on the machines in the math department, in the directory c:\program files\winscp3. Once it is installed, you can start the program and point it at a Unix machine, as shown in the figure. The name of the machine we want to put or get files from is The port number of 22 is the default. Use your account name and password, then click the Login button. If you have not contacted the remote machine before, WinSCP will ask you whether you want to accept its secret key. Just say yes. If you did not enter your password in the original connection box, you will be required to do so next. After that, you should see a window similar to the one shown. The contents of your home directory on the remote machine are on the right, the contents of your local directory are on the left. You may drag and drop files in the same way s if you were using Windows explorer, except in this case, the files are transferred to or from a different computer.

By right-clicking a file name, you can even edit or run the file. However, before this happens the file is transferred to the local machine. This is key: all actions happen on the local machine, WinSCP does not allow you to run programs on the other computer.

If you want to use machine cycles on the remote computer, you must use a different program. Putty is an SSH (Secure SHell) client for Windows. It is again available free on the Internet. Again, you need only to specify the machine you want to connect to, and make sure you use the right protocol. For the latter purpose, be sure to click the SSH button in the middle right of the dialog box. You can save the session settings by giving them a name and clicking the Save button in the middle of the box. There are other setting where you can specify the login name to use, the color of the window, and so on. All can be saved. After you start the session, you may be prompted for your login name and password.

Once logged in, you are actually using the processor of the remote machine to execute your commands. You can write and run programs, and do all the other things you would expect on a computer. Here we have asked for details on the processes running on the remote machine - information we could not get through WinSCP. The key thing to remember in all this is that the connection is encrypted. Nobody between you and the remote machine can understand what is passing over the wires or through the airwaves, because it is all encoded. This includes the psword you send, and any sensitive information you might enter.