Apache HTTP Server Version 1.3

Apache Server Frequently Asked Questions

The latest version of this FAQ is always available from the main Apache web site, at <http://httpd.apache.org/docs/misc/FAQ.html>.

If you are reading a text-only version of this FAQ, you may find numbers enclosed in brackets (such as "[12]"). These refer to the list of reference URLs to be found at the end of the document. These references do not appear, and are not needed, for the hypertext version.

The Questions

1. Background
   1. What is Apache?
   2. How and why was Apache created?
   3. Why the name "Apache"?
   4. OK, so how does Apache compare to other servers?
   5. How thoroughly tested is Apache?
   6. What are the future plans for Apache?
   7. Whom do I contact for support?
   8. Is there any more information on Apache?
   9. Where can I get Apache?
   10. May I use the Apache logo on my product or Web site?
2. General Technical Questions
   1. "Why can't I ...? Why won't ... work?" What to do in case of problems
   2. How compatible is Apache with my existing NCSA 1.3 setup?
   3. Is Apache Year 2000 compliant?
   4. How do I submit a patch to the Apache Group?
   5. Why has Apache stolen my favourite site's Internet address?
   6. Why am I getting spam mail from the Apache site?
   7. May I include the Apache software on a CD or other package I'm distributing?
   8. What's the best hardware/operating system/... How do I get the most out of my Apache Web server?
   9. What are "regular expressions"?
   10. Why isn't there a binary for my platform?
3. Building Apache
   1. Why do I get an error about an undefined reference to "__inet_ntoa" or other __inet_* symbols?
   2. Why won't Apache compile with my system's cc?
   3. Why do I get complaints about redefinition of "struct iovec" when compiling under Linux?
   4. I'm using gcc and I get some compilation errors, what is wrong?
   5. I'm using RedHat Linux 5.0, or some other glibc-based Linux system, and I get errors with the crypt function when I attempt to build Apache 1.2.
4. Error Log Messages and Problems Starting Apache
   1. Why do I get "setgid: Invalid argument" at startup?
   2. Why am I getting "httpd: could not set socket option TCP_NODELAY" in my error log?
   3. Why am I getting "connection reset by peer" in my error log?
   4. The errorlog says Apache dumped core, but where's the dump file?
   5. When I run it under Linux I get "shmget: function not found", what should I do?
   6. Server hangs, or fails to start, and/or error log fills with "fcntl: F_SETLKW: No record locks available" or similar messages
   7. Why am I getting "Expected </Directory> but saw </Directory>" when I try to start Apache?
   8. I'm using RedHat Linux and I have problems with httpd dying randomly or not restarting properly
   9. I upgraded from an Apache version earlier than 1.2.0 and suddenly I have problems with Apache dying randomly or not restarting properly
   10. When I try to start Apache from a DOS window, I get a message like "Cannot determine host name. Use ServerName directive to set it manually." What does this mean?
   11. When I try to start Apache for Windows, I get a message like "Unable To Locate WS2_32.DLL...". What should I do?
   12. Apache for Windows does not start. Error log contains this message "[crit] (10045) The attempted operation is not supported for the type of object referenced: Parent: WSADuplicateSocket failed for socket ###". What does this mean?
   13. When I try to start Apache on Windows, I get a message like "System error 1067 has occurred. The process terminated unexpectedly." What does this mean?
   14. On a SuSE Linux system, I try and configure access control using basic authentication. Although I follow the example exactly, authentication fails, and an error message "admin: not a valid FDN: ...." is logged.
   15. Why do I have weird entries in my logs asking for default.ida and cmd.exe?
   16. Why am I getting server restart messages periodically, when I did not restart the server?
   17. Why am I getting "module module-name is not compatible with this version of Apache" messages in my error log?
5. Configuration Questions
   1. Why can't I run more than <n> virtual hosts?
   2. Can I increase FD_SETSIZE on FreeBSD?
   3. Why doesn't my ErrorDocument 401 work?
   4. Why does Apache send a cookie on every response?
   5. Why don't my cookies work, I even compiled in mod_cookies?
   6. Why do my Java app[let]s give me plain text when I request an URL from an Apache server?
   7. How do I get Apache to send a MIDI file so the browser can play it?
   8. How do I add browsers and referrers to my logs?
   9. Why does accessing directories only work when I include the trailing "/" (e.g., http://foo.domain.com/~user/) but not when I omit it (e.g., http://foo.domain.com/~user)?
   10. Why doesn't mod_info list any directives?
   11. I upgraded to Apache 1.3 and now my virtual hosts don't work!
   12. I'm using RedHat Linux and my .htm files are showing up as HTML source rather than being formatted!
   13. My .htaccess files are being ignored.
   14. Why do I get a "Forbidden" message whenever I try to access a particular directory?
   15. Why do I get a "Forbidden/You don't have permission to access / on this server" message whenever I try to access my server?
   16. Why do my files appear correctly in Internet Explorer, but show up as source or trigger a save window with Netscape; or, Why doesn't Internet Explorer render my text/plain document correctly?
   17. My site is accessible under many different hostnames; how do I redirect clients so that they see only a single name?
   18. Why can I access my website from the server or from my local network, but I can't access it from elsewhere on the Internet?
   19. How do I turn automatic directory listings on or off?
   20. Why do my Options directives not have the desired effect?
   21. How can I change the information that Apache returns about itself in the headers?
   22. Why do I see requests for other sites appearing in my log files?
6. Dynamic Content (CGI and SSI)
   1. How do I enable CGI execution in directories other than the ScriptAlias?
   2. What does it mean when my CGIs fail with "Premature end of script headers"?
   3. Why do I keep getting "Method Not Allowed" for form POST requests?
   4. How can I get my script's output without Apache buffering it? Why doesn't my server push work?
   5. Where can I find the "CGI specification"?
   6. Why isn't FastCGI included with Apache any more?
   7. How do I enable SSI (parsed HTML)?
   8. Why don't my parsed files get cached?
   9. How can I have my script output parsed?
   10. SSIs don't work for VirtualHosts and/or user home directories
   11. How can I use ErrorDocument and SSI to simplify customized error messages?
   12. Why is the environment variable REMOTE_USER not set?
   13. How do I allow each of my user directories to have a cgi-bin directory?
7. Authentication and Access Restrictions
   1. Why isn't restricting access by host or domain name working correctly?
   2. How do I set up Apache to require a username and password to access certain documents?
   3. How do I set up Apache to allow access to certain documents only if a site is either a local site or the user supplies a password and username?
   4. Why does my authentication give me a server error?
   5. Do I have to keep the (mSQL) authentication information on the same machine?
   6. Why is my mSQL authentication terribly slow?
   7. Can I use my /etc/passwd file for Web page authentication?
   8. Why does Apache ask for my password twice before serving a file?
   9. How can I prevent people from "stealing" the images from my web site?
8. URL Rewriting
   1. Where can I find mod_rewrite rulesets which already solve particular URL-related problems?
   2. Where can I find any published information about URL-manipulations and mod_rewrite?
   3. Why is mod_rewrite so difficult to learn and seems so complicated?
   4. What can I do if my RewriteRules don't work as expected?
   5. Why don't some of my URLs get prefixed with DocumentRoot when using mod_rewrite?
   6. How can I make all my URLs case-insensitive with mod_rewrite?
   7. Why are RewriteRules in my VirtualHost parts ignored?
   8. How can I use strings with whitespaces in RewriteRule's ENV flag?
9. Features
   1. Does or will Apache act as a Proxy server?
   2. What are "multiviews"?
   3. Why can't I publish to my Apache server using PUT on Netscape Gold and other programs?
   4. Why doesn't Apache include SSL?
   5. How can I attach a footer to my documents without using SSI?
   6. Does Apache include a search engine?
   7. How can I rotate my log files?
   8. How do I keep certain requests from appearing in my logs?
   9. Does Apache include any sort of database integration?
   10. Can I use Active Server Pages (ASP) with Apache?
   11. Does Apache come with Java support?

The Answers

A. Background

1. What is Apache?

   The Apache httpd server

   • is a powerful, flexible, HTTP/1.1 compliant web server
   • implements the latest protocols, including HTTP/1.1 (RFC2616)
   • is highly configurable and extensible with third-party modules
   • can be customised by writing 'modules' using the Apache module API
   • provides full source code and comes with an unrestrictive license
   • runs on Windows NT/9x, Netware 5.x and above, OS/2, and most versions of Unix, as well as several other operating systems
   • is actively being developed
   • encourages user feedback through new ideas, bug reports and patches
   • implements many frequently requested features, including:
     
     

     DBM databases for authentication

     allows you to easily set up password-protected pages with enormous numbers of authorized users, without bogging down the server.

     Customized responses to errors and problems

     Allows you to set up files, or even CGI scripts, which are returned by the server in response to errors and problems, e.g. setup a script to intercept 500 Server Errors and perform on-the-fly diagnostics for both users and yourself.

     Multiple DirectoryIndex directives

     Allows you to say DirectoryIndex index.html index.cgi, which instructs the server to either send back index.html or run index.cgi when a directory URL is requested, whichever it finds in the directory.

     Unlimited flexible URL rewriting and aliasing

     Apache has no fixed limit on the numbers of Aliases and Redirects which may be declared in the config files. In addition, a powerful rewriting engine can be used to solve most URL manipulation problems.

     Content negotiation

     i.e. the ability to automatically serve clients of varying sophistication and HTML level compliance, with documents which offer the best representation of information that the client is capable of accepting.

     Virtual Hosts

     A much requested feature, sometimes known as multi-homed servers. This allows the server to distinguish between requests made to different IP addresses or names (mapped to the same machine). Apache also offers dynamically configurable mass-virtual hosting.

     Configurable Reliable Piped Logs

     You can configure Apache to generate logs in the format that you want. In addition, on most Unix architectures, Apache can send log files to a pipe, allowing for log rotation, hit filtering, real-time splitting of multiple vhosts into separate logs, and asynchronous DNS resolving on the fly.

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2. How and why was Apache created?

   The About Apache document explains how the Apache project evolved from its beginnings as an outgrowth of the NCSA httpd project to its current status as one of the fastest, most efficient, and most functional web servers in existence.

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3. Why the name "Apache"?

   The name 'Apache' was chosen from respect for the Native American Indian tribe of Apache (Indé), well-known for their superior skills in warfare strategy and their inexhaustible endurance. For more information on the Apache Nation, we suggest searching Google, Northernlight, or AllTheWeb.

   Secondarily, and more popularly (though incorrectly) accepted, it's a considered cute name which stuck. Apache is "A PAtCHy server". It was based on some existing code and a series of "patch files".

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4. OK, so how does Apache compare to other servers?

   For an independent assessment, see Web Compare.

   Apache has been shown to be substantially faster, more stable, and more feature-full than many other web servers. Although certain commercial servers have claimed to surpass Apache's speed (it has not been demonstrated that any of these "benchmarks" are a good way of measuring WWW server speed at any rate), we feel that it is better to have a mostly-fast free server than an extremely-fast server that costs thousands of dollars. Apache is run on sites that get millions of hits per day, and they have experienced no performance difficulties.

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5. How thoroughly tested is Apache?

   Apache is run on over 6 million Internet servers (as of February 2000). It has been tested thoroughly by both developers and users. The Apache Group maintains rigorous standards before releasing new versions of their server, and our server runs without a hitch on over one half of all WWW servers available on the Internet. When bugs do show up, we release patches and new versions as soon as they are available.

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6. What are the future plans for Apache?
   • to continue to be an "open source" no-charge-for-use HTTP server,
   • to keep up with advances in HTTP protocol and web developments in general,
   • to collect suggestions for fixes/improvements from its users,
   • to respond to needs of large volume providers as well as occasional users.

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7. Whom do I contact for support?

   There is no official support for Apache. None of the developers want to be swamped by a flood of trivial questions that can be resolved elsewhere. Bug reports and suggestions should be sent via the bug report page. Other questions should be directed to the Apache HTTP Server Users List or the comp.infosystems.www.servers.unix or comp.infosystems.www.servers.ms-windows newsgroup (as appropriate for the platform you use), where some of the Apache team lurk, in the company of many other httpd gurus who should be able to help.

   Commercial support for Apache is, however, available from a number of third parties.

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8. Is there any more information available on Apache?

   Indeed there is. See the main Apache web site. There is also a regular electronic publication called Apache Week available. Links to relevant Apache Week articles are included below where appropriate. There are also some Apache-specific books available.

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9. Where can I get Apache?

   You can find out how to download the source for Apache at the project's main web page.

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10. May I use the Apache logo on my product or Web site?

    You may NOT use any original artwork from the Apache Software Foundation, nor make or use modified versions of such artwork, except under the following conditions:

    • You may use the 'Powered by Apache' graphic on a Web site that is being served by the Apache HTTP server software.
    • You may use the aforementioned 'Powered by Apache' graphic or the Apache Software Foundation logo in product description and promotional material IF and ONLY IF such use can in no way be interpreted as anything other than an attribution. Using the Apache name and artwork in a manner that implies endorsement of a product or service is strictly forbidden.

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B. General Technical Questions

1. "Why can't I ...? Why won't ... work?" What to do in case of problems

   If you are having trouble with your Apache server software, you should take the following steps:

   1. Check the errorlog!

      Apach