WebDAV: This is how the HTTP extension works

WebDAV is a trans­mis­sion protocol which makes it possible to make files or complete di­rec­to­ries available through the Internet and  transmit them to various devices. In this article, we explain what this protocol is all about exactly, what its benefits are and what WebDAV al­ter­na­tives are available.

The WebDAV protocol was developed by three working groups of the IETF (Internet En­gi­neer­ing Task Force). The initiator was Jim Whitehead, who founded the group in 1996 after a meeting with Sir Tim Berners Lee, the inventor of the World Wide Web. Sir Tim Berners Lee had orig­i­nal­ly planned the Internet so that web pages could not only be read by anyone, but also edited by anyone. However, as the editing options were not able to be im­ple­ment­ed with the basic protocol set for practical reasons, Whitehead and Lee jointly developed the idea into WebDAV. A first version of the protocol was specified in 1999 in RFC 2518. The current version of the trans­mis­sion protocol can be found in RFC 4918.

In order to use WebDAV to transfer data, both client and server must support the protocol. Since this is an es­tab­lished standard, all popular web servers actually enable cor­re­spond­ing im­ple­men­ta­tion. And various operating systems such as Windows (since XP), macOS or Linux now also offer standard support for trans­mis­sions via the WebDAV protocol.

For example, with Windows you don’t need any ad­di­tion­al software or drivers. You can set up and establish a WebDAV con­nec­tion to a server within Explorer, which then displays the ap­pro­pri­ate platform for data exchange as if it were a computer drive. Con­verse­ly, this also means that you can open, edit and erase files stored there or save them to the server as usual in Windows. The transfer protocol enables users access to cloud files or files on a separate server in real time, without the hassle of down­load­ing, caching, editing and uploading.

Setting up a con­nec­tion with WebDAV varies for each provider. Usually, there is the pos­si­bil­i­ty to set up access man­age­ment or a log-in on the server. This access can then later be used to transfer files via the protocol. In addition to an in­di­vid­ual username and password, these log-in details always include, among other things, the IP address of the server.

Setting up a con­nec­tion to a WebDAV server on Windows is rel­a­tive­ly easy. Follow these steps:

1. Open Windows Explorer.
2. Click with the right mouse button on “This PC” and select the option “Add network location”.
3. Click on “Choose a custom network location” and enter the IP address of the WebDAV server.
4. Click “Next”.
5. In the now opened window, enter your log-in details and confirm this to complete the setup process.
6. Under “This PC” you should now also find the newly es­tab­lished access to the WebDAV server, among other things.

Since WebDAV uses HTTP, it also uses HTTP standard port 80 for the trans­mis­sion, which is not usually blocked by firewalls. With alternate transfer methods such as FTP or SSH, ad­di­tion­al ports often require au­tho­riza­tion in the firewall settings. This is not only as­so­ci­at­ed with an increased con­fig­u­ra­tion effort, but also entails ad­di­tion­al security risks. When trans­mit­ting via WebDAV, however, data security is not en­dan­gered by such problems. As the ad­di­tion­al setup effort is otherwise omitted, (es­pe­cial­ly as a WebDAV server can be easily in­te­grat­ed within an existing HTTP server) system ad­min­is­tra­tors also save a lot of time and effort.

Which servers and clients are com­pat­i­ble with the WebDAV protocol? The following list provides an overview.

• Apache HTTP Server: various WebDAV modules based on either the Linux tool davfs2 or the version man­age­ment Apache Sub­ver­sion (SVN)
• Microsoft IIS: pro­pri­etary WebDAV module
• NGINX: pro­pri­etary, very limited WebDAV module or option to purchase a third-party module
• SabreDAV: PHP ap­pli­ca­tion that can be used in Apache or NGINX as a WebDAV at­tach­ment instead of the supplied modules
• ownCloud: Cloud storage ap­pli­ca­tion with full WebDAV support
• Nextcloud: ownCloud sub­sidiary, which also provides WebDAV support
• lighttpd: optional module available
• Caddy: optional module available

• Git
• Linux
• macOS (including native support for CalDAV and CardDAV, which rely on WebDAV)
• Microsoft Windows
• Microsoft Office

WebDAV is part of the Internet protocol family. The al­ter­na­tives to the WebDAV protocol are listed below. The two most commonly used al­ter­na­tives to the WebDAV protocol are FTP and SFTP:

• FTP (File Transfer Protocol): Simple network protocol that allows the transfer of files in computer networks; can be combined with SSL/TLS (FTPS) for secure data traffic
• SSH File Transfer Protocol (SFTP): A sup­ple­ment to FTP through the Secure Shell (SSH) protocol, which provides the transport protocol with ad­di­tion­al secure file transfer ca­pa­bil­i­ties

There are also the following al­ter­na­tives:

• Rsync: Protocol and tool for syn­chro­niz­ing files
• AtomPub: HTTP-based protocol for creating and updating web resources
• Content Man­age­ment In­ter­op­er­abil­i­ty Services (CMIS): Open standard that enables various content man­age­ment systems to exchange in­for­ma­tion over the Internet
• Wiki software: For example, MediaWiki
• Linked Data Platform (LDP): Spec­i­fi­ca­tion for linked data