FTP/S (File Transfer Protocol over Secure Sockets Layers)Īlong with file transfers, clients will typically request directory information from the FTP server. For security reasons, companies are limiting the number of ports in their publicly facing firewalls and looking for alternate solutions in order to keep ports closed and information secure. FTP traditionally requires a block of ports to remain open on either the server firewall or the client firewall to aid with the creation of Data Connections. The need for a Data Connection, and its inherent security loopholes, is a major concern in internet usage today. This is somewhat more secure because the user’s password does not go over the wire– only a hash of the user’s password– so a MITMA usually can’t reverse engineer the password from the hash. If the hashes of the password match, they are authenticated. The client presents this hash to the server, which takes the user’s password, already stored on the server, and uses the same digits. The client grabs those digits and, using a pre-known algorithm such as ROT13 or MD5, the client will generate a hash of their password along with the series of digits to produce a unique password (used one time, hence the OTP). There’s an exception to this rule called One Time Password ( OTP), in which the server sends a series of digits to the client server in response to the receipt of the USER command. This makes FTP very unsecure it would not be terribly difficult for a third party, such as a Man-in-the-Middle Attacker (MITMA), to steal users’ credentials. The conversation between client and server is performed in plain text-all communication between the two parties is sent unprotected, verbatim, over the internet. The Control Connection remains idle until the end of this exchange, when it reports that the file transfer has either failed or was completed successfully. After authentication, the client and server will typically, through a series of synchronized commands controlled by the Command Connection, negotiate a new common port called the Data Connection over which the file will be transferred. The FTP client will usually authenticate itself with the FTP server by sending over a username and a password. This main connection is called the Control Connection or Command Connection. An FTP server will listen for client connections on port 21.įTP clients will then connect to the FTP server on port 21 and initiate a conversation. The FTP protocol typically uses port 21 as its main means of communication. One computer acts as the server to store information and the other acts as the client to send or request files from the server. FTP (File Transfer Protocol)įTP is a very well-established protocol, developed in the 1970s to allow two computers to transfer data over the internet. SFTP is a completely different protocol (in spite of the similar acronym) that is natively secure and more efficient. FTP/S takes the security up a step in that it allows you to secure all or part of a session (at the cost of speed). FTP, FTP/S, and SFTP are common acronyms, but did you know that there are some significant differences among them? Notably, FTP in its basic form is not secure.
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