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 uses and relies on TCP to ensure all the packets of data are sent correctly and to the proper destination.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. When an FTP client requests to connect to an FTP server, a TCP connection is being established using the application layer within TCP and ports 20 and 21. Link Layer: separate from the other layers, this layer describes protocols that exist only through one link that a host is connected to. Internet Layer: takes the network packets from the transport layer and sends them to the proper destinations based on their IP addresses. Transport Layer: creates and delivers the data packets passed on from the application layer to the appropriate host devices by adding source and destination port numbers and maintaining the end-to-end network connections. Protocols include: FTP, HTTP, IMAP, SMTP, SSH TCP and IP use the four-layer model that separates the protocols based on their functions.Īpplication Layer: standardizes the communication for data exchange between programs or devices and uses ports to pass data along to the transport layer. This frees up network paths for more requests since they are all considered unique connections and can be used continuously. Once the server has completed the request from the client, the connection is dissolved. IP: addresses and routes the packets of data to make sure they reach the right destination and device within the network.īased on the “end-to-end” and “client/server” communication models, TCP/IP features are separated based on functions into layers where one program or device (the client) can request a service from another program or device (the server). TCP: creates the link that allows the devices to connect and determines how data is packaged into smaller packets before being transmitted, and then reassembled after transfer. The Internet Protocol Suite, better known as TCP/IP, is a set of communications rules that allow two or more network devices to communicate.
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