Computing Service

File Transfer (SFTP, SCP, FTP)

Comparison of FTP, SCP and SFTP

FTP or File Transfer Protocol has been in use for many years as the primary method for transferring files from one computer system to another. FTP clients and servers are very widely available. However, there are security problems with FTP; when you set up an FTP connection, your password on the remote system is transmitted without any form of encryption. FTP is therefore not generally recommended, except for anonymous FTP.

Furthermore, there are security issues associated with some FTP servers, which have led to a block being imposed on incoming FTP transfers to Cambridge systems, except for a list of approved systems (see FTP blocking for more details).

The secure alternatives to FTP are SFTP (rather like FTP, with slightly fewer facilities but with extra security features) and SCP (Secure Copy). Neither of these is universally available, and they have different advantages.

The main difference in practical operation between SCP and SFTP/FTP is that for SFTP or FTP you set up a connection and can then carry out a whole series of operations (including many which are not actually transfers, such as listing or even deleting files on the remote system). With many SCP clients, a single command normally transfers a single file or group of files, and to list files on the remote system, for instance, you have to login as a separate exercise (normally using an SSH client). Note that WinSCP, although described as an SCP client, provides facilities more like those of FTP or SFTP, and offers an SFTP mode as an option.

Computing Service systems

None of the main Computing Service systems runs a plain FTP server. The Hermes filestore runs SSH servers for SFTP and SCP; the PWF has an SFTP server but does not accept SCP. Note that the Hermes mailstore is not accessed by any of these methods; to transfer mail folders, use the facilities of Hermes Webmail.

Client programs are not provided on Hermes since Hermes does not allow users to run general programs.

All PWF systems provide client programs for SFTP, SCP and FTP, as follows:

To find out whether a system to or from which you need to transfer files runs an FTP or SSH server, you need to ask the administrators of the system (or simply try one of the client programs and see if it works). Individuals running their own systems should not normally need to run FTP or SSH servers, and should be aware of security issues if they do so.

To find out about client programs, you may also need to ask the administrators of the local systems. Obtaining File Transfer Clients gives pointers to sources for various FTP/SFTP/SCP clients.

Select from the lefthand menu for details of SFTP, FTP and SCP.

The title of this document is: University Computing Service: File Transfer; comparison of ftp, sftp, scp
URL: http://www.cam.ac.uk/cs/filetransfer/compare.html

Last updated: February 2009