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<title>Self-certifying File System</title>

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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Self-certifying File System</span></span>

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<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p>In computing, <b>Self-certifying File System</b> (<b>SFS</b>) is a global and decentralized, <a href="Distributed_file_system" class="mw-redirect" title="Distributed file system">distributed file system</a> for <a href="Unix-like" title="Unix-like">Unix-like</a> operating systems, while also providing transparent <a href="Encryption" title="Encryption">encryption</a> of communications as well as <a href="Authentication" title="Authentication">authentication</a>. It aims to be the universal distributed file system by providing uniform access to any available server, however, the usefulness of SFS is limited by the low deployment of SFS clients. It was developed in the June 2000 doctoral thesis of <a rel="nofollow" class="external text" href="https://profiles.stanford.edu/david-mazieres">David Mazières</a>.

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<div class="mw-heading mw-heading2"><h2 id="Implementation">Implementation</h2></div>

<p>The SFS <a href="Client_(computing)" title="Client (computing)">client</a> <a href="Daemon_(computer_software)" class="mw-redirect" title="Daemon (computer software)">daemon</a> implements the Sun's <a href="Network_File_System_(protocol)" class="mw-redirect" title="Network File System (protocol)">Network File System</a> (NFS) protocol for communicating with the <a href="Operating_system" title="Operating system">operating system</a>, and thus can work on any operating system that supports NFS, including <a href="Microsoft_Windows" title="Microsoft Windows">Windows</a>.<sup id="cite_ref-sfs-windows_1-0" class="reference"><a href="#cite_note-sfs-windows-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> The client manages connections to remote file systems as necessary, acting as a kind of protocol translation layer. The SFS server works similarly to other distributed file system servers, by exposing an existing <a href="Disk_file_system" class="mw-redirect" title="Disk file system">disk file system</a> over the network, over the specific SFS protocol. On <a href="Unix-like" title="Unix-like">Unix-like</a> systems, SFS file systems can usually be found at <style data-mw-deduplicate="TemplateStyles:r886049734">

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</style><span class="monospaced">/sfs/hostname:hostID</span>. When an SFS file system is first accessed through this path, a connection to the server is made and the directory is created ("automounted").

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<div class="mw-heading mw-heading2"><h2 id="Differences">Differences</h2></div>

<p>The primary motivation behind the file system is to address the shortcomings of <a href="https://en.wiktionary.org/wiki/hardwired" class="extiw external" title="wikt:hardwired">hardwired</a>, administratively configured distributed file systems in larger organizations, and various remote file transfer protocols. It is designed to operate securely between separate administrative realms. For example, with SFS, one could store all their files on a single remote server, and access the same files securely and transparently from any location as if they were stored locally, without any special privileges or administrative cooperation (other than running the SFS client daemon). Available file systems will be found at the same path regardless of physical location, and are implicitly authenticated by their path names — as they include the <a href="Public-key_fingerprint" class="mw-redirect" title="Public-key fingerprint">public-key fingerprint</a> of the server (hence why it is called "self-certifying").<sup id="cite_ref-selfcert_2-0" class="reference"><a href="#cite_note-selfcert-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>In addition to the new perspective, SFS also addresses some commonly raised limitations of other distributed file systems. For example, NFS and <a href="Server_Message_Block" title="Server Message Block">SMB</a> clients have to rely on the server for file system security policies, and NFS servers have to rely on the client computer for authentication. This often complicates security, as one compromised computer could breach the security of the entire organization. The NFS and SMB protocols also do not by themselves provide <a href="Confidentiality" title="Confidentiality">confidentiality</a> (encryption) or <a href="Tamper_resistance" class="mw-redirect" title="Tamper resistance">tamper resistance</a> from other computers on the network, without encapsulation layers such as <a href="IPsec" title="IPsec">IPsec</a>.

</p><p>Unlike <a href="Coda_(file_system)" title="Coda (file system)">Coda</a> and <a href="Andrew_File_System" title="Andrew File System">AFS</a>, SFS does not provide local <a href="Cache_(computing)" title="Cache (computing)">caching</a> of remote files and thus is more dependent on network reliability, <a href="Latency_(engineering)" title="Latency (engineering)">latency</a> and <a href="Bandwidth_(computing)" title="Bandwidth (computing)">bandwidth</a>.

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<ul><li><a href="Clustered_file_system" title="Clustered file system">Clustered file system</a></li>

<li><a href="Network_File_System_(protocol)" class="mw-redirect" title="Network File System (protocol)">Network File System (protocol)</a></li>

<li><a href="Coda_(file_system)" title="Coda (file system)">Coda (file system)</a></li>

<li><a href="Andrew_File_System" title="Andrew File System">Andrew File System</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

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</style><cite id="CITEREFDavid_Euresti2002" class="citation web cs1">David Euresti (August 2002). <a rel="nofollow" class="external text" href="http://pdos.csail.mit.edu/papers/sfs:euresti-meng.ps">"Self-Certifying File System Implementation for Windows"</a> <span class="cs1-format">(PostScript)</span>. <a href="MIT" class="mw-redirect" title="MIT">MIT</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2006-12-23</span></span>.</cite></span>

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<li id="cite_note-selfcert-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-selfcert_2-0">^</a></b></span> <span class="reference-text"><cite id="CITEREFDavid_Mazières,_M._Frans_Kaashoek1998" class="citation conference cs1">David Mazières, <a href="M._Frans_Kaashoek" class="mw-redirect" title="M. Frans Kaashoek">M. Frans Kaashoek</a> (September 1998). <a rel="nofollow" class="external text" href="http://www.scs.stanford.edu/~dm/home/papers/mazieres:escape.ps.gz"><i>Escaping the Evils of Centralized Control with self-certifying pathnames</i></a> <span class="cs1-format">(<a href="PostScript" title="PostScript">PostScript</a>)</span>. Proceedings of the 8th <a href="Association_for_Computing_Machinery" title="Association for Computing Machinery">ACM</a> SIGOPS European workshop: Support for composing distributed applications. Sintra, Portugal: <a href="MIT" class="mw-redirect" title="MIT">MIT</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2006-12-23</span></span>.</cite></span>

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<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080502061505/http://www.fs.net/sfswww/">archive of SFS official web site (archive.org)</a>* <cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080725193436/http://www.fs.net/sfswww/sfsfaq.html">"Self-certifying File System: FAQ"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.fs.net/sfswww/sfsfaq.html">the original</a> on July 25, 2008.</cite></li>

<li><cite id="CITEREFDavid_Mazières2000" class="citation journal cs1">David Mazières (May 2000). <a rel="nofollow" class="external text" href="http://pdos.csail.mit.edu/~ericp/doc/sfs-thesis.ps">"Self-certifying File System"</a> <span class="cs1-format">(PostScript)</span>. <i>PhD Thesis</i>. <a href="MIT" class="mw-redirect" title="MIT">MIT</a><span class="reference-accessdate">. Retrieved <span class="nowrap">2012-01-16</span></span>.</cite></li></ul></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2023-03-29" href="https://en.wikipedia.org/wiki/?title=Self-certifying_File_System&oldid=1147138577">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

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