Differences between SFTP and “FTP over SSH”

Question

While looking for an SFTP client in C# SSH File Transfer Protocol (SFTP), I\'ve come across these two suitable projects - one and two.

While trying to understand the

Answer 1

Basically, there are the following file transfer protocols around:

• FTP – the plain old FTP protocol that has been around since 1970s. The acronym stands for "File Transfer Protocol". It usually runs over TCP port 21.

• SFTP – another, completely different file transfer protocol that has nothing to do with FTP. SFTP runs over an SSH session, usually on TCP port 22. It has been around since late 1990s. The acronym actually stands for "SSH File Transfer Protocol".

• FTP over SSH - 1) possible, but extremely rare example of FTP protocol tunneled through a SSH channel 2) incorrectly named SFTP

(for details see "Secure FTP, FTP/SSL, SFTP, FTPS, FTP, SCP... What's the difference?" page at Rebex)

Disclaimer: I work for Rebex

Answer 2

• SFTP stands for SSH File Transfer Protocol. It's not FTP over SSL and not FTP over SSH. SFTP is standardized in RFC 4253.
• FTP stands for File Transfer Protocol which is defined by RFC 959 and latter additions. FTP is very popular but not secured. Therefore FTP over SSL was introduced and it's called FTPS or FTP/SSL.

For authentication SFTP use SSH keys, while FTPS use X.509 certificates.

Answer 3

I just created a .NET SFTP Library. One of the things I learned in the process is how different FTP is to SFTP. You are actually communicating with an SSH server instead of an FTP server. It's not just the protocol, the commands are totally different that you are sending to the SSH server.

Here is a link to my library.

Answer 4

Here is the difference:

• SFTP (SSH file transfer protocol) is a protocol that provides file transfer and manipulation capabilities. It can work over any reliable data stream, but is typically used with SSH
• "FTP over SSH" uses the regular old FTP protocol, but an SSH tunnel is placed between client and server.

You probably won't find libraries for "FTP over SSH" because typically the tunnel is set up by running an SSH command, and once it is set up, clients and servers don't need to know about the tunnel; they just open ports and transfer data they way they would without a tunnel.

BTW, yet another option for you might be FTP over SSL (FTPS), which is supported by .NET. (See http://msdn.microsoft.com/en-us/library/system.net.ftpwebrequest.enablessl.aspx.)

Answer 5

SFTP is it's own protocol. FTP over SSH is using FTP once you're connected via SSH.

Answer 6

SFTP is actually another protocol that runs over SSH - an extension of SSH if you like. People tend to use SFTP rather than tunnelling FTP over SSH.

For comprehensive SFTP support in .NET try edtFTPnet/PRO. It's been around a long time with support for many different SFTP servers.