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The Postfix Home Page
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>The Postfix Home Page</title> <meta name="google-site-verification" content="Nx2UG7gprc0LCFx3AGqDBJD-dZXkMJFYwMjlC7qYZPg"> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <link rel='stylesheet' type='text/css' href='postfix.css'> </head> <div id='left'> <p> <img src="mysza.gif" width="130" height="91" alt="[LOGO]"> </p> <p class='navhead'>QUICK LINKS</p> <p class='nav'><a href="start.html">Home</a> </p> <p class='nav'><a href="announcements.html">Announcements</a> </p> <!-- <p class='nav'><a href="non-english.html">Non-English Info</a> </p> --> <p class='nav'><a href="features.html">Feature overview </a> </p> <p class='nav'><a href="web-sites.html">Web sites (text)</a> </p> <p class='nav'><a href="download.html">Download (source)</a> </p> <p class='nav'><a href="lists.html">Mailing lists</a> </p> <p class='nav'><a href="press.html">Press and Interviews</a> </p> <p class='nav'><a href="documentation.html">Documentation</a> </p> <!-- <p class='nav'><a href="docs.html">Howtos and FAQs</a> </p> --> <p class='nav'><a href="addon.html">Add-on Software</a> </p> <p class='nav'><a href="packages.html">Packages and Ports</a> </p> <p class='nav'><a href="mirror.html">Becoming a mirror site</a> </p> <p class='navhead'></p> <form method="get" action="https://www.google.com/search"> <p class='nav'> <input size="-1" type="submit" value="Search"><br> <input type="text" name="q" size="16" maxlength="255" value=""> <input type="hidden" name="sitesearch" value="www.postfix.org"> </p> </form> </div> <div id='main'> <h1> The Postfix Home Page</h1> <blockquote><p><i> All programmers are optimists </i> -- Frederick P. Brooks, Jr. </p></blockquote> <p> First of all, thank you for your interest in the Postfix project. </p> <p> What is Postfix? It is <a href="http://www.porcupine.org/wietse/">Wietse Venema's</a> mail server that started life at <a href="https://www.research.ibm.com">IBM research</a> as an alternative to the widely-used <a href="https://www.sendmail.org/">Sendmail</a> program. After eight years at Google, <i>Wietse continues to maintain Postfix</i>. </p> <p> Postfix attempts to be fast, easy to administer, and secure. The outside has a definite Sendmail-ish flavor, but the inside is completely different. </p> <!-- <h2> Newsflash </h2> <p> SMTP Smuggling Attack: an email spoofing attack was published a few days before Christmas 2023, before people had an opportunity to update their Postfix and other mail systems. Updates are now available for all supported Postfix stable releases. More at <a href="smtp-smuggling.html"> smtp-smuggling.html</a>. </p> <p> A recent twitter post reveals the existence of an exploit for Postfix, in a collection of what appear to be NSA break-in tools. </p> <a href="https://twitter.com/JulianAssange/status/850870683831648256"> https://twitter.com/JulianAssange/status/850870683831648256</a> <p> This is an exploit for Postfix 2.0 - 2.2, for a bug that was fixed 11 years ago in Postfix 2.2.11 and later. </p> <p> There was a memory corruption bug in a Postfix workaround for a Sendmail bug (CERT advisory CA-2003-07, remote buffer overflow in Sendmail when message headers contain lots of comment text before or after an email address). </p> <p> Technical details: the Postfix strip_address() function, which removes large comments from a mail header, called the printable() function on a string that wasn't null-terminated. This caused the printable() function to scribble past the end of malloc()ed memory, corrupting the memory heap. </p> <p> Running the exploit against Postfix versions less than 11 years old results in odd-looking email messages in the super-user's mailbox, and warning messages in the maillog file (warning: stripping too many comments from address: <long character string>). </p> <p>As of July 2015, all supported Postfix releases have new TLS default settings that no longer enable export-grade ciphers, and no longer enable the SSLv2 and SSLv3 protocols. These ciphers and protocols have little if any legitimate use today, and have instead become a vehicle for downgrade attacks. See the <a href="announcements/postfix-3.0.2.html">announcement</a> for more. </p> <p>Logjam Attack: this has mostly the same countermeasure as FREAK: disable EXPORT ciphers on the SMTP server side, as described under the next bullet. </p> <p>FREAK Attack: To protect vulnerable clients execute as root "<tt>postconf smtpd_tls_exclude_ciphers=EXPORT; postfix reload</tt>". This command removes EXPORT ciphers with opportunistic as well as mandatory TLS. The impact of this attack was already low because each Postfix SMTP server process computes its own own "ephemeral" RSA key and terminates after a limited time. </p> <p>GHOST Attack: Postfix does not call gethostbyname() since 2005. There is no Postfix code that invokes this function unless Postfix is specifically built for operating systems from more than 10 years ago (this requires the compile-time option "<tt>-DNO_IPV6</tt>"). </p> --> <h2> About this website </h2> <p> This website has information about the Postfix source code distribution. Built from source code, Postfix can run on UNIX-like systems including AIX, BSD, HP-UX, Linux, MacOS X, Solaris, and more. </p> <p> Postfix is also distributed as ready-to-run code by operating system vendors, appliance vendors, and other providers. Their versions may have small differences with the software that is described on this website. </p> </div> </body></html>