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FTP
File Transfer Protocol
- Standard FTP
- Typically runs over TCP port 21
- Stream based protocol, The TCP/IP transport layer handles the flow control sending a signal to acknowledge the receipt of data transparently.
- The FTP client establishes two connections to the server, a control connection and data connection. A new data connection is established for each file transfer and directory listing.
Pros
- Widely known and used
- Fast file transfers
- Site to site transfers (provided the FTP server allows it)
Cons
- FTP is by default an insecure protocol, during login the password is sent in clear-text over the network,
unless the client and server support S/KEY or OTP (One time password) authentication
- Requires a secondary DATA channel, which makes it hard to use behind the firewalls
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FTP/SSL
File Transfer Protocol over TLS/SSL
- Often called 'FTPS'
- Typically runs over TCP port 21 or 990
- Standard FTP over TLS/SSL encrypted channel
- Explicit SSL - The FTP client sends a command ( i.e. "AUTH SSL" or "AUTH TLS") to the ftp server to establish a secure control connection.
- Implicit SSL - The connection is automatically secure as soon as the FTP client makes a connection to the FTP server. Typically port 990 is used in this configuration.
- Stream based protocol, The TCP/IP transport layer handles the flow control sending a signal to acknowledge the receipt of data transparently.
Pros
- Password is encrypted
- Transfer is encrypted
- Site to site transfers (However, not all FTP servers support secure site to site transfers)
Cons
- Not all FTP servers support SSL/TLS
- Requires a secondary DATA channel, which makes it hard to use behind the firewalls
- Slightly slower than FTP due to the encryption/decryption.
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SFTP
SSH File Transfer Protocol
- SSH File Transfer Protocol
- SFTP is a completely different protocol from traditional FTP
- Typically runs over TCP port 22
- Packet based protocol, The SSH protocol handles the flow control sending a signal to acknowledge the receipt of data. This is done on top of underlaying TCP/IP.
- SFTP uses a single connection for sending commands and data.
Pros
- The connection is always secure
- Password is encrypted
- Transfer is encrypted
- SFTP is considerably more firewall friendly than FTP because it only requires one port to establish a connection and carry out file operations.
Cons
- Much slower than FTP or FTP/SSL because the protocol is
encrypted and packet based.
- No support for site to site transfers
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