File Service Protocol (FSP) is a UDP-based replacement for the

File Transfer Protocol The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and dat ...

, designed for anonymous access with lower hardware and network requirements than FTP. In particular, because it uses UDP, it avoids the problems that many FTP servers have had with requiring a separate process for each client, and because it is built to use an unreliable protocol, it can more easily handle resuming a transfer after a network failure.

History

FSP never reached the popularity of FTP for legitimate use (although wuarchive and

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provided FSP service in addition to FTP for some time), but became very popular in the early-to-mid-1990s for

underground Underground most commonly refers to: * Subterranea (geography), the regions beneath the surface of the Earth Underground may also refer to: Places * The Underground (Boston), a music club in the Allston neighborhood of Boston * The Underground ...

sites containing pornography and/or

warez Warez is a common computing and broader cultural term referring to pirated software (i.e. illegally copied, often after deactivation of anti-piracy measures) that is distributed via the Internet. Warez is used most commonly as a noun, a plural ...

. Because an FSP server only requires one process (as opposed to one process per client for most FTP servers), it is much harder for a

system administrator A system administrator, or sysadmin, or admin is a person who is responsible for the upkeep, configuration, and reliable operation of computer systems, especially multi-user computers, such as servers. The system administrator seeks to en ...

to notice it in a process list; also, since it uses UDP, it is less likely to be noticed by a

network administrator A network administrator is a person designated in an organization whose responsibility includes maintaining computer infrastructures with emphasis on local area networks (LANs) up to wide area networks (WANs). Responsibilities may vary between org ...

. Eventually, however, an increased use of

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spr ...

s, a decreasing usage of the

shell account A shell account is a user account on a remote server, traditionally running under the Unix operating system, which gives access to a shell via a command-line interface protocol such as telnet, SSH, or over a modem using a terminal emulator. S ...

s required to run a server or most of the clients, and a lack of FSP support in

web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used o ...

s caused its use to taper off, and the

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moved to

HTTP The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide We ...

and FXP while pornography moved to publicly advertised web servers.

Port number

As the FSP protocol is not officially recognized by IANA, it has no official

port number In computer networking, a port is a number assigned to uniquely identify a connection endpoint and to direct data to a specific service. At the software level, within an operating system, a port is a logical construct that identifies a specific ...

. However, as a UDP equivalent of FTP, official FSP servers frequently run on UDP port 21, which is the same as FTP's TCP port number. Because FSP uses UDP and FTP uses TCP they can both run at same time on the same port number without conflict. Unofficial servers may run on any port, although 2121 was a popular choice. (On most *nix systems, only the

root user In computing, the superuser is a special user account used for system administration. Depending on the operating system (OS), the actual name of this account might be root, administrator, admin or supervisor. In some cases, the actual name of th ...

can start a process that listens on a port under 1024.)

Protocol name

The name ''FSP'' was originally created without a real expansion. In 1993, discussions were held about what to expand the acronym to; the ultimate result was ''File Service Protocol''. Other suggestions included ''File Slurping Protocol'', ''FTP's Sexier Partner'', and ''Flaky Stream Protocol''. Due to its inherent low performance, FSP was sometimes colloquially said to stand for "Fucking Slow Protocol" .

References

External links

FSP Protocol Home Page

File Service Protocol (FSP) Frequently Asked Questions

Comparisons of FSP with other FTP-like transfer protocols over Wi-Fi
* {{Cite web, url=http://www.720k.net/, title=FSP ARCHIVE (File Service Protocol) Windows Clients, Servers, Apps, website=www.720k.net, access-date=2020-01-16 Network file transfer protocols