{"id":20471,"date":"2020-01-29T23:05:42","date_gmt":"2020-01-29T23:05:42","guid":{"rendered":"https:\/\/www.arimetrics.com\/glosario-digital\/ftp"},"modified":"2026-10-02T11:31:14","modified_gmt":"2026-10-02T11:31:14","slug":"ftp","status":"publish","type":"encyclopedia","link":"https:\/\/www.arimetrics.com\/en\/digital-glossary\/ftp","title":{"rendered":"FTP"},"content":{"rendered":"<p><img decoding=\"async\" class=\"boxpad alignright size-full wp-image-14332\" style=\"margin-top:0;\" src=\"https:\/\/www.arimetrics.com\/wp-content\/uploads\/2020\/01\/FTP-1.png\" alt=\"FTP\" width=\"300\" height=\"300\" srcset=\"https:\/\/www.arimetrics.com\/wp-content\/uploads\/2020\/01\/FTP-1.png 300w, https:\/\/www.arimetrics.com\/wp-content\/uploads\/2020\/01\/FTP-1-150x150.png 150w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><strong>Definition:<\/strong><\/p>\n<p><strong>FTP<\/strong> stands for <em>File Transfer Protocol<\/em>. It is a network protocol for copying files, listing directories and performing other operations between a client and server over a TCP-based connection.<\/p>\n<p>FTP was designed to exchange files between systems connected to a network and is one of the historic protocols of the <a href=\"https:\/\/www.arimetrics.com\/en\/digital-glossary\/internet\">Internet<\/a>. Its main specification appears in <a href=\"https:\/\/www.rfc-editor.org\/rfc\/rfc959.html\" target=\"_blank\" rel=\"noopener\">RFC 959<\/a>, although extensions and additional mechanisms were introduced later.<\/p>\n\n<h2>FTP architecture<\/h2>\n<p>FTP uses a client-server architecture with two separate connections:<\/p>\n<ul>\n<li><strong>FTP client:<\/strong> starts the session and sends commands to authenticate, navigate or transfer files.<\/li>\n<li><strong>FTP server:<\/strong> accepts connections, checks permissions and performs authorized operations.<\/li>\n<li><strong>Control channel:<\/strong> maintains the session and carries commands and replies; it normally uses port 21 on the server.<\/li>\n<li><strong>Data channel:<\/strong> carries directory listings and file contents over a separate connection.<\/li>\n<\/ul>\n<p>This separation of channels distinguishes FTP from protocols such as <a href=\"https:\/\/www.arimetrics.com\/en\/digital-glossary\/http\">HTTP<\/a>. It does not make one a version of the other: they use different models and commands.<\/p>\n<h2>How an FTP transfer works<\/h2>\n<p>A typical session can be summarized as follows:<\/p>\n<ol>\n<li><strong>Connection:<\/strong> the client opens the control channel with the server.<\/li>\n<li><strong>Authentication:<\/strong> it sends a username and password or uses anonymous access when the server permits it.<\/li>\n<li><strong>Navigation:<\/strong> it lists directories and changes the working location through protocol commands.<\/li>\n<li><strong>Data mode selection:<\/strong> the client and server agree on how to establish the connection that will carry the content.<\/li>\n<li><strong>Transfer:<\/strong> the client downloads, uploads, renames or deletes files according to its permissions.<\/li>\n<li><strong>Closure:<\/strong> the session ends and the connections used are closed.<\/li>\n<\/ol>\n<p>FTP supports ASCII and binary transfer modes. ASCII mode can transform text-file line endings between systems; binary mode preserves the bytes and is appropriate for images, executables, compressed files and most current formats.<\/p>\n<h2>Active and passive FTP<\/h2>\n<p>Active and passive modes determine which party initiates the data connection:<\/p>\n<ul>\n<li><strong>Active FTP:<\/strong> the client specifies a port and the server initiates the data connection to it.<\/li>\n<li><strong>Passive FTP:<\/strong> the server announces an available port and the client also initiates the data connection.<\/li>\n<li><strong>Firewalls and NAT:<\/strong> active mode can be problematic when the client does not accept incoming connections.<\/li>\n<li><strong>Common use:<\/strong> passive mode usually works more readily with home networks, firewalls and address translation.<\/li>\n<\/ul>\n<p>These modes do not encrypt the communication. They only change how the data channel is established.<\/p>\n<h2>What FTP is used for<\/h2>\n<p>FTP can support manual and automated tasks:<\/p>\n<ul>\n<li><strong>Publishing web files:<\/strong> transferring assets to a <a href=\"https:\/\/www.arimetrics.com\/en\/digital-glossary\/hosting\">hosting<\/a> server when the provider supports the protocol.<\/li>\n<li><strong>Distributing files:<\/strong> providing downloads from a repository or server organized into directories.<\/li>\n<li><strong>Exchanging large volumes:<\/strong> moving sets of files without relying on email.<\/li>\n<li><strong>Maintaining legacy systems:<\/strong> communicating with equipment and processes that still use FTP.<\/li>\n<li><strong>Automating transfers:<\/strong> running scheduled uploads or retrievals with scripts and command-line clients.<\/li>\n<\/ul>\n<p>FTP does not synchronize files by itself like a <a href=\"https:\/\/www.arimetrics.com\/en\/digital-glossary\/cloud-computing\">cloud computing<\/a> service. An application can compare directories and schedule transfers, but that logic belongs to the client or system using the protocol.<\/p>\n<h2>FTP, FTPS and SFTP differences<\/h2>\n<p>All three names relate to file transfer, but they do not identify the same protocol:<\/p>\n<ul>\n<li><strong>FTP:<\/strong> uses its own control and data channels and, in its original form, does not encrypt credentials or content.<\/li>\n<li><strong>FTPS:<\/strong> extends FTP with TLS to protect authentication and transfers. It retains the FTP architecture and commands.<\/li>\n<li><strong>SFTP:<\/strong> is a file transfer protocol that operates over SSH. It is not encapsulated FTP or an FTP extension.<\/li>\n<li><strong>Compatibility:<\/strong> a server providing FTP or FTPS does not necessarily support SFTP, and the reverse is also true.<\/li>\n<li><strong>Ports and configuration:<\/strong> each option requires services, network rules and credentials appropriate to the protocol being used.<\/li>\n<\/ul>\n<p><a href=\"https:\/\/www.arimetrics.com\/en\/digital-glossary\/encryption\">Encryption<\/a> protects content in transit, but it does not replace permission management, server updates or credential protection.<\/p>\n<h2>FTP clients and security measures<\/h2>\n<p>An FTP client may provide a graphical interface, command-line access, queues and automation. Its configuration should account for:<\/p>\n<ul>\n<li><strong>Selected protocol:<\/strong> FTP, FTPS and SFTP must not be configured as though they were interchangeable.<\/li>\n<li><strong>Server identity:<\/strong> TLS certificates or SSH keys help verify the destination of the connection.<\/li>\n<li><strong>Credentials:<\/strong> individual accounts, strong passwords and limited permissions should be used.<\/li>\n<li><strong>Anonymous access:<\/strong> it should only be enabled for resources and operations intended to be public.<\/li>\n<li><strong>Logs:<\/strong> authentication and transfer events support investigation of errors or unauthorized access.<\/li>\n<li><strong>Network exposure:<\/strong> ports and passive ranges should be limited to what is required.<\/li>\n<\/ul>\n<p>When compatibility with unencrypted FTP is not required, FTPS or SFTP protect communications against direct reading of credentials and files in transit.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>What FTP is, how file transfers work, how active and passive modes differ, and how FTP compares with FTPS and SFTP.<\/p>\n","protected":false},"author":6,"featured_media":0,"template":"","encyclopedia-tag":[1267,1458],"class_list":["post-20471","encyclopedia","type-encyclopedia","status-publish","hentry","encyclopedia-tag-web-infrastructure","encyclopedia-tag-web-server-infrastructure"],"_links":{"self":[{"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/encyclopedia\/20471","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/encyclopedia"}],"about":[{"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/types\/encyclopedia"}],"author":[{"embeddable":true,"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/users\/6"}],"wp:attachment":[{"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/media?parent=20471"}],"wp:term":[{"taxonomy":"encyclopedia-tag","embeddable":true,"href":"https:\/\/www.arimetrics.com\/en\/wp-json\/wp\/v2\/encyclopedia-tag?post=20471"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}