Difference Between FTP Server and FTP Client - yogada.info
The FTP server can support both active and passive connections with the FTP client. In an active FTP connection, the client opens a port and listens while the. FTP is a client-server protocol that relies on two communications channels What is the difference between TCP/IP model and OSI model?. Because FTP uses the TCP (networking) protocol, it operates though a reliable connection as a transfer "session" between the client (host) and server (remote).
Files are transferred through the data connection and an ongoing transfer could be stopped by sending an abort signal over the control connection.
What is an FTP client and how do I use one?
What is FTP Client? Most often, a FTP client is a personal computer or a mobile device that is running application software that is able to communicate with and retrieve files from a FTP server.
To connect with a FTP server, client first needs to provide the destination server it wants to connect to and the required credentials such as a user name and a password. After the connection is set up, the client can begin the file transferring process.
What is FTP (File Transfer Protocol)?
There are lots of free and commercial FTP client software that support different platforms. These client software ranges from simple command line applications to GUI applications that provides a more user friendly environment. Generally, FTP server is a high performance device that holds the files and databases holding information that is required to satisfy the requests coming from FTP clients.
FTP client is a personal computer or a mobile device that runs a software application that is capable of communicating with a FTP server and retrieve files from it. FTP server always keeps on listening to incoming requests and the client initiates the communication session by opening a control connection with the server. These features were designed to facilitate files containing Telnet or ASA.
Data transfer can be done in any of three modes: Data is sent as a continuous stream, relieving FTP from doing any processing. Rather, all processing is left up to TCP.
No End-of-file indicator is needed, unless the data is divided into records. FTP breaks the data into several blocks block header, byte count, and data field and then passes it on to TCP.
Difference Between FTP Server and FTP Client
Data is compressed using a simple algorithm usually run-length encoding. This mode was described in an Internet Draftbut not standardized. Although users are commonly asked to send their email address instead of a password,  no verification is actually performed on the supplied data. This is problematic for both NATs and firewalls, which do not allow connections from the Internet towards internal hosts.
There are two approaches to solve this problem. FTP has a stateful control connection which maintains a current working directory and other flags, and each transfer requires a secondary connection through which the data are transferred.
In "passive" mode this secondary connection is from client to server, whereas in the default "active" mode this connection is from server to client.
What is File Transfer Protocol - FTP | Serv-U
This apparent role reversal when in active mode, and random port numbers for all transfers, is why firewalls and NAT gateways have such a hard time with FTP. HTTP is stateless and multiplexes control and data over a single connection from client to server on well-known port numbers, which trivially passes through NAT gateways and is simple for firewalls to manage. Setting up an FTP control connection is quite slow due to the round-trip delays of sending all of the required commands and awaiting responses, so it is customary to bring up a control connection and hold it open for multiple file transfers rather than drop and re-establish the session afresh each time.
In contrast, HTTP originally dropped the connection after each transfer because doing so was so cheap. While HTTP has subsequently gained the ability to reuse the TCP connection for multiple transfers, the conceptual model is still of independent requests rather than a session.
When FTP is transferring over the data connection, the control connection is idle. If the transfer takes too long, the firewall or NAT may decide that the control connection is dead and stop tracking it, effectively breaking the connection and confusing the download.