Overview of the FTP protocol.
In the early days of the Internet, applications were mostly restricted to mail transfer (email) and file transfer. FTP (File Transfer Protocol) is one of the first standardized protocols for exchanging binary and text files between hosts.
FTP is rather simple in that it uses a TCP connection for exchanging commands and a data transfer TCP connection for the actual file transfer.
In normal FTP operation, the client opens the control connection to the FTP server while it is up to the server to open data connections for each file transfer. With the upcoming firewalls, this scheme proved to pose a problem since firewalls tend to block incoming TCP connections. Thus a passive mode was defined where the client is responsible to open the data connection to the server.
Clipping is a handy way to collect important slides you want to go back to later.