Configuring Your Macintosh or PC for Secure File Transfer Douglas Pitters Network Services Exchanging files has never been easier. You no longer need to carry diskettes from office to office. If you and your colleagues are on MITnet (and thus the Internet), you can exchange files over the network using the File Transfer Protocol (FTP). FTP is the standard Internet pro-tocol for moving files from one computer to another. The ftp command lets you copy (put) files from your computer to any other computer on the Internet to which you have access. Similarly, FTP lets you retrieve (get) files from other computers on the Internet. The Client-Server Setup FTP uses a client-server approach: to connect to other machines on the network via FTP, you need to use an FTP client, and for other users on the Internet to connect to your machine, you need to set up a server on your local machine. To use FTP, your computer must be connected to MITnet (or any network that uses TCP/IP protocols), and it must be running the proper network software. Macintosh users must have MacTCP installed, and DOS/Windows users must have LAN WorkPlace for DOS installed. Recommended FTP Applications There are two FTP server applications that IS recommends and supports for DOS and Windows users. The program Serving FTP runs in the background under Windows and allows up to five simultaneous FTP sessions. The DOS utility FTPD allows one remote user to connect; when in use, FTPD takes over your computer. Both applications come with the LAN WorkPlace suite of network applications. For Macintosh users running System 7 or later, IS recommends NCSA Telnet 2.6. In addition to providing Kerberized telnet, this program lets you run an FTP server in the background that allows multiple remote connections to your machine. Security Issues If you plan to leave your FTP server unattended for an extended period, or plan to let users connect to your FTP server on a regular basis, you should be concerned about security. If you don't take appropriate measures, any user that connects to the FTP server on your Macintosh or DOS/Windows machine will have access to all your files. One way to prevent unwanted connections to your server is to require users to supply a viable username and password. Access restriction will prevent unwanted users from connecting to your machine and accessing personal files. Password protection is strongly suggested when using any of the available FTP server applications. Macintosh users running NCSA Telnet can take additional preventive measures by setting up default directories (i.e., default folders; see NCSA Telnet 2.6: Setting Up an FTP Server, Using Telnet 2.6 on a Macintosh [NS-36]). Default directories help localize transfers to one area of your hard drive, resulting in quick and easy transfers, and better disk space management. Setting up Directories In the FTP world, it's a convention to store files that you want users to download (using the get command) in a directory called "pub." Similarly, you may want to create a directory called "incoming" for files that users upload onto your machine (using the put command). You can use additional directories to keep different kinds of files separate from each other. A Caveat and Pointer to Resources FTP isn't always a one-step panacea. You may still need tools to compress or decompress large files. And if the files you're retrieving were created on a different type of computer than yours, there will still be issues of file conversion. If you need help with file compression or conversion utilities, call the Network Help Desk at x3- 4101 or send e-mail to . You can also contact them for more information about using NCSA Telnet 2.6, Serving FTP for Windows, or FTPD for DOS. Assorted articles about FTP are posted on TechInfo. To see a listing, search on the keyword FTP. .