Apache - Documentation - 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 Background What is Apache? How and why was Apache created? Why the name "Apache"? OK, so how does Apache compare to other servers? How thoroughly tested is Apache? What are the future plans for Apache? Whom do I contact for support? Is there any more information on Apache? Where can I get Apache? May I use the Apache logo on my product or Web site? Go back to index Have unlimited websites hosted for only $5.95 a month! Check out our new Hosting Plans! Note: Documentation is made available for our clients. The application's homepage is located at Apache.org

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!

      Apache tries to be helpful when it encounters a problem. In many cases, it will provide some details by writing one or messages to the server error log. Sometimes this is enough for you to diagnose & fix the problem yourself (such as file permissions or the like). The default location of the error log is /usr/local/apache/logs/error_log, but see the ErrorLog directive in your config files for the location on your server.

   2. Check the FAQ!

      The latest version of the Apache Frequently-Asked Questions list can always be found at the main Apache web site.

   3. Check the Apache bug database

      Most problems that get reported to The Apache Group are recorded in the bug database. Please check the existing reports, open and closed, before adding one. If you find that your issue has already been reported, please don't add a "me, too" report. If the original report isn't closed yet, we suggest that you check it periodically. You might also consider contacting the original submitter, because there may be an email exchange going on about the issue that isn't getting recorded in the database.

   4. Ask in a user support group.

      A lot of common problems never make it to the bug database because there's already high Q&A traffic about them in the Users mailing list or comp.infosystems.www.servers.unix and related newsgroups. These newsgroups are also available via Google. Many Apache users, and some of the developers, can be found roaming their virtual halls, so it is suggested that you seek wisdom there. The chances are good that you'll get a faster answer there than from the bug database, even if you don't see your question already posted.

   5. If all else fails, report the problem in the bug database

      If you've gone through those steps above that are appropriate and have obtained no relief, then please do let The Apache Group know about the problem by logging a bug report.

      If your problem involves the server crashing and generating a core dump, please include a backtrace (if possible). As an example,

      # cd ServerRoot
# dbx httpd core
(dbx) where

      (Substitute the appropriate locations for your ServerRoot and your httpd and core files. You may have to use gdb instead of dbx.)

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2. How compatible is Apache with my existing NCSA 1.3 setup?

   Apache attempts to offer all the features and configuration options of NCSA httpd 1.3, as well as many of the additional features found in NCSA httpd 1.4 and NCSA httpd 1.5.

   NCSA httpd appears to be moving toward adding experimental features which are not generally required at the moment. Some of the experiments will succeed while others will inevitably be dropped. The Apache philosophy is to add what's needed as and when it is needed.

   Friendly interaction between Apache and NCSA developers should ensure that fundamental feature enhancements stay consistent between the two servers for the foreseeable future.

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3. Is Apache Year 2000 compliant?

   Yes, Apache is Year 2000 compliant.

   Apache internally never stores years as two digits. On the HTTP protocol level RFC1123-style addresses are generated which is the only format a HTTP/1.1-compliant server should generate. To be compatible with older applications Apache recognizes ANSI C's asctime() and RFC850-/RFC1036-style date formats, too. The asctime() format uses four-digit years, but the RFC850 and RFC1036 date formats only define a two-digit year. If Apache sees such a date with a value less than 70 it assumes that the century is 20 rather than 19.

   Although Apache is Year 2000 compliant, you may still get problems if the underlying OS has problems with dates past year 2000 (e.g., OS calls which accept or return year numbers). Most (UNIX) systems store dates internally as signed 32-bit integers which contain the number of seconds since 1^st January 1970, so the magic boundary to worry about is the year 2038 and not 2000. But modern operating systems shouldn't cause any trouble at all.

   Users of Apache 1.2.x should upgrade to a current version of Apache 1.3 (see year-2000 improvements in Apache 1.3 for details).

   The Apache HTTP Server project is an open-source software product of the Apache Software Foundation. The project and the Foundation cannot offer legal assurances regarding any suitability of the software for your application. There are several commercial Apache support organizations and derivative server products available that may be able to stand behind the software and provide you with any assurances you may require. You may find links to some of these vendors at <http://www.apache.org/info/support.cgi>.

   The Apache HTTP server software is distributed with the following disclaimer, found in the software license:

      THIS SOFTWARE IS PROVIDED BY THE APACHE GROUP ``AS IS'' AND ANY
      EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
      PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE APACHE GROUP OR
      ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
      SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
      NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
      LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
      STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
      OF THE POSSIBILITY OF SUCH DAMAGE.
    
   

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4. How do I submit a patch to the Apache Group?

   The Apache Group encourages patches from outside developers. There are 2 main "types" of patches: small bugfixes and general improvements. Bugfixes should be submitting using the Apache bug report page. Improvements, modifications, and additions should follow the instructions below.

   In general, the first course of action is to be a member of the dev@httpd.apache.org mailing list. This indicates to the Group that you are closely following the latest Apache developments. Your patch file should be generated using either 'diff -c' or 'diff -u' against the latest CVS tree. To submit your patch, send email to dev@httpd.apache.org with a Subject: line that starts with [PATCH] and includes a general description of the patch. In the body of the message, the patch should be clearly described and then included at the end of the message. If the patch-file is long, you can note a URL to the file instead of the file itself. Use of MIME enclosures/attachments should be avoided.

   Be prepared to respond to any questions about your patches and possibly defend your code. If your patch results in a lot of discussion, you may be asked to submit an updated patch that incorporates all changes and suggestions.

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5. Why has Apache stolen my favourite site's Internet address?

   The simple answer is: "It hasn't." This misconception is usually caused by the site in question having migrated to the Apache Web server software, but not having migrated the site's content yet. When Apache is installed, the default page that gets installed tells the Webmaster the installation was successful. The expectation is that this default page will be replaced with the site's real content. If it doesn't, complain to the Webmaster, not to the Apache project -- we just make the software and aren't responsible for what people do (or don't do) with it.

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6. Why am I getting spam mail from the Apache site?

   The short answer is: "You aren't." Usually when someone thinks the Apache site is originating spam, it's because they've traced the spam to a Web site, and the Web site says it's using Apache. See the previous FAQ entry for more details on this phenomenon.

   No marketing spam originates from the Apache site. The only mail that comes from the site goes only to addresses that have been requested to receive the mail.

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7. May I include the Apache software on a CD or other package I'm distributing?

   The detailed answer to this question can be found in the Apache license, which is included in the Apache distribution in the file LICENSE. You can also find it on the Web at <http://www.apache.org/LICENSE.txt>.

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8. What's the best hardware/operating system/... How do I get the most out of my Apache Web server?

   Check out Dean Gaudet's performance tuning page.

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9. What are "regular expressions"?

   Regular expressions are a way of describing a pattern - for example, "all the words that begin with the letter A" or "every 10-digit phone number" or even "Every sentence with two commas in it, and no capital letter Q". Regular expressions (aka "regex"s) are useful in Apache because they let you apply certain attributes against collections of files or resources in very flexible ways - for example, all .gif and .jpg files under any "images" directory could be written as /\/images\/.*(jpg|gif)$/.

   The best overview around is probably the one which comes with Perl. We implement a simple subset of Perl's regex support, but it's still a good way to learn what they mean. You can start by going to the CPAN page on regular expressions, and branching out from there.

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10. Why isn't there a binary for my platform?

    The developers make sure that the software builds and works correctly on the platforms available to them; this does not necessarily mean that your platform is one of them. In addition, the Apache HTTP server project is primarily source oriented, meaning that distributing valid and buildable source code is the purpose of a release, not making sure that there is a binary package for all of the supported platforms.

    If you don't see a kit for your platform listed in the binary distribution area (<URL:http://httpd.apache.org/dist/httpd/binaries/>), it means either that the platform isn't available to any of the developers, or that they just haven't gotten around to preparing a binary for it. As this is a voluntary project, they are under no obligation to do so. Users are encouraged and expected to build the software themselves.

    The sole exception to these practices is the Windows package. Unlike most Unix and Unix-like platforms, Windows systems do not come with a bundled software development environment, so we do prepare binary kits for Windows when we make a release. Again, however, it's a voluntary thing and only a limited number of the developers have the capability to build the InstallShield package, so the Windows release may lag somewhat behind the source release. This lag should be no more than a few days at most.

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C. Building Apache

1. Why do I get an error about an undefined reference to "__inet_ntoa" or other __inet_* symbols?

   If you have installed BIND-8 then this is normally due to a conflict between your include files and your libraries. BIND-8 installs its include files and libraries /usr/local/include/ and /usr/local/lib/, while the resolver that comes with your system is probably installed in /usr/include/ and /usr/lib/. If your system uses the header files in /usr/local/include/ before those in /usr/include/ but you do not use the new resolver library, then the two versions will conflict.

   To resolve this, you can either make sure you use the include files and libraries that came with your system or make sure to use the new include files and libraries. Adding -lbind to the EXTRA_LDFLAGS line in your Configuration file, then re-running Configure, should resolve the problem. (Apache versions 1.2.* and earlier use EXTRA_LFLAGS instead.)

   Note:As of BIND 8.1.1, the bind libraries and files are installed under /usr/local/bind by default, so you should not run into this problem. Should you want to use the bind resolvers you'll have to add the following to the respective lines:

   EXTRA_CFLAGS=-I/usr/local/bind/include
EXTRA_LDFLAGS=-L/usr/local/bind/lib
EXTRA_LIBS=-lbind

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2. Why won't Apache compile with my system's cc?

   If the server won't compile on your system, it is probably due to one of the following causes:

   • The Configure script doesn't recognize your system environment.
     This might be either because it's completely unknown or because the specific environment (include files, OS version, et cetera) isn't explicitly handled. If this happens, you may need to port the server to your OS yourself.
   • Your system's C compiler is garbage.
     Some operating systems include a default C compiler that is either not ANSI C-compliant or suffers from other deficiencies. The usual recommendation in cases like this is to acquire, install, and use gcc.
   • Your include files may be confused.
     In some cases, we have found that a compiler installation or system upgrade has left the C header files in an inconsistent state. Make sure that your include directory tree is in sync with the compiler and the operating system.
   • Your operating system or compiler may be out of revision.
     Software vendors (including those that develop operating systems) issue new releases for a reason; sometimes to add functionality, but more often to fix bugs that have been discovered. Try upgrading your compiler and/or your operating system.

   The Apache Group tests the ability to build the server on many different platforms. Unfortunately, we can't test all of the OS platforms there are. If you have verified that none of the above issues is the cause of your problem, and it hasn't been reported before, please submit a problem report. Be sure to include complete details, such as the compiler & OS versions and exact error messages.

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3. Why do I get complaints about redefinition of "struct iovec" when compiling under Linux?

   This is a conflict between your C library includes and your kernel includes. You need to make sure that the versions of both are matched properly. There are two workarounds, either one will solve the problem:

   • Remove the definition of struct iovec from your C library includes. It is located in /usr/include/sys/uio.h. Or,
   • Add -DNO_WRITEV to the EXTRA_CFLAGS line in your Configuration and reconfigure/rebuild. This hurts performance and should only be used as a last resort.

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4. I'm using gcc and I get some compilation errors, what is wrong?

   GCC parses your system header files and produces a modified subset which it uses for compiling. This behavior ties GCC tightly to the version of your operating system. So, for example, if you were running IRIX 5.3 when you built GCC and then upgrade to IRIX 6.2 later, you will have to rebuild GCC. Similarly for Solaris 2.4, 2.5, or 2.5.1 when you upgrade to 2.6. Sometimes you can type "gcc -v" and it will tell you the version of the operating system it was built against.

   If you fail to do this, then it is very likely that Apache will fail to build. One of the most common errors is with readv, writev, or uio.h. This is not a bug with Apache. You will need to re-install GCC.

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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.

   glibc puts the crypt function into a separate library. Edit your src/Configuration file and set this:

   EXTRA_LIBS=-lcrypt

   Then re-run src/Configure and re-execute the make.

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D. Error Log Messages and Problems Starting Apache

1. Why do I get "setgid: Invalid argument" at startup?

   Your Group directive (probably in conf/httpd.conf) needs to name a group that actually exists in the /etc/group file (or your system's equivalent). This problem is also frequently seen when a negative number is used in the Group directive (e.g., "Group #-1"). Using a group name -- not group number -- found in your system's group database should solve this problem in all cases.

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2. Why am I getting "httpd: could not set socket option TCP_NODELAY" in my error log?

   This message almost always indicates that the client disconnected before Apache reached the point of calling setsockopt() for the connection. It shouldn't occur for more than about 1% of the requests your server handles, and it's advisory only in any case.

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3. Why am I getting "connection reset by peer" in my error log?

   This is a normal message and nothing about which to be alarmed. It simply means that the client canceled the connection before it had been completely set up - such as by the end-user pressing the "Stop" button. People's patience being what it is, sites with response-time problems or slow network links may experience this more than high capacity ones or those with large pipes to the network.

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4. The errorlog says Apache dumped core, but where's the dump file?

   In Apache version 1.2, the error log message about dumped core includes the directory where the dump file should be located. However, many Unixes do not allow a process that has called setuid() to dump core for security reasons; the typical Apache setup has the server started as root to bind to port 80, after which it changes UIDs to a non-privileged user to serve requests.

   Dealing with this is extremely operating system-specific, and may require rebuilding your system kernel. Consult your operating system documentation or vendor for more information about whether your system does this and how to bypass it. If there is a documented way of bypassing it, it is recommended that you bypass it only for the httpd server process if possible.

   The canonical location for Apache's core-dump files is the ServerRoot directory. As of Apache version 1.3, the location can be set via the CoreDumpDirectory directive to a different directory. Make sure that this directory is writable by the user the server runs as (as opposed to the user the server is started as).

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5. When I run it under Linux I get "shmget: function not found", what should I do?

   Your kernel has been built without SysV IPC support. You will have to rebuild the kernel with that support enabled (it's under the "General Setup" submenu). Documentation for kernel building is beyond the scope of this FAQ; you should consult the Kernel HOWTO, or the documentation provided with your distribution, or a Linux newsgroup/mailing list. As a last-resort workaround, you can comment out the #define USE_SHMGET_SCOREBOARD definition in the LINUX section of src/conf.h and rebuild the server (prior to 1.3b4, simply removing #define HAVE_SHMGET would have sufficed). This will produce a server which is slower and less reliable.

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6. Server hangs, or fails to start, and/or error log fills with "fcntl: F_SETLKW: No record locks available" or similar messages

   These are symptoms of a fine locking problem, which usually means that the server is trying to use a synchronization file on an NFS filesystem.

   Because of its parallel-operation model, the Apache Web server needs to provide some form of synchronization when accessing certain resources. One of these synchronization methods involves taking out locks on a file, which means that the filesystem whereon the lockfile resides must support locking. In many cases this means it can't be kept on an NFS-mounted filesystem.

   To cause the Web server to work around the NFS locking limitations, include a line such as the following in your server configuration files:

   LockFile /var/run/apache-lock

   The directory should not be generally writable (e.g., don't use /var/tmp). See the LockFile documentation for more information.

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7. Why am I getting "Expected </Directory> but saw </Directory>" when I try to start Apache?

   This is a known problem with certain versions of the AIX C compiler. IBM are working on a solution, and the issue is being tracked by problem report #2312.

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8. I'm using RedHat Linux and I have problems with httpd dying randomly or not restarting properly

   RedHat Linux versions 4.x (and possibly earlier) RPMs contain various nasty scripts which do not stop or restart Apache properly. These can affect you even if you're not running the RedHat supplied RPMs.

   If you're using the default install then you're probably running Apache 1.1.3, which is outdated. From RedHat's ftp site you can pick up a more recent RPM for Apache 1.2.x. This will solve one of the problems.

   If you're using a custom built Apache rather than the RedHat RPMs then you should rpm -e apache. In particular you want the mildly broken /etc/logrotate.d/apache script to be removed, and you want the broken /etc/rc.d/init.d/httpd (or httpd.init) script to be removed. The latter is actually fixed by the apache-1.2.5 RPMs but if you're building your own Apache then you probably don't want the RedHat files.

   We can't stress enough how important it is for folks, especially vendors to follow the stopping Apache directions given in our documentation. In RedHat's defense, the broken scripts were necessary with Apache 1.1.x because the Linux support in 1.1.x was very poor, and there were various race conditions on all platforms. None of this should be necessary with Apache 1.2 and later.

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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

   You should read the previous note about problems with RedHat installations. It is entirely likely that your installation has start/stop/restart scripts which were built for an earlier version of Apache. Versions earlier than 1.2.0 had various race conditions that made it necessary to use kill -9 at times to take out all the httpd servers. But that should not be necessary any longer. You should follow the directions on how to stop and restart Apache.

   As of Apache 1.3 there is a script src/support/apachectl which, after a bit of customization, is suitable for starting, stopping, and restarting your server.

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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?

    It means what it says; the Apache software can't determine the hostname of your system. Edit your conf\httpd.conf file, look for the string "ServerName", and make sure there's an uncommented directive such as

    ServerName localhost

    or

    ServerName www.foo.com

    in the file. Correct it if there one there with wrong information, or add one if you don't already have one.

    Also, make sure that your Windows system has DNS enabled. See the TCP/IP setup component of the Networking or Internet Options control panel.

    After verifying that DNS is enabled and that you have a valid hostname in your ServerName directive, try to start the server again.

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11. When I try to start Apache for Windows, I get a message like "Unable To Locate WS2_32.DLL...". What should I do?

    Short answer: You need to install Winsock 2, available from http://www.microsoft.com/windows95/downloads/

    Detailed answer: Prior to version 1.3.9, Apache for Windows used Winsock 1.1. Beginning with version 1.3.9, Apache began using Winsock 2 features (specifically, WSADuplicateSocket()). WS2_32.DLL implements the Winsock 2 API. Winsock 2 ships with Windows NT 4.0 and Windows 98. Some of the earlier releases of Windows 95 did not include Winsock 2.

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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?

    We have seen this problem when Apache is run on systems along with Virtual Private Networking clients like Aventail Connect. Aventail Connect is a Layered Service Provider (LSP) that inserts itself, as a "shim," between the Winsock 2 API and Window's native Winsock 2 implementation. The Aventail Connect shim does not implement WSADuplicateSocket, which is the cause of the failure.

    The shim is not unloaded when Aventail Connect is shut down. Once observed, the problem persists until the shim is either explicitly unloaded or the machine is rebooted. Another potential solution (not tested) is to add apache.exe to the Aventail "Connect Exclusion List".

    Apache is affected in a similar way by any firewall program that isn't correctly configured. Assure you exclude your Apache server ports (usually port 80) from the list of ports to block. Refer to your firewall program's documentation for the how-to.

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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?

    This message means that the Web server was unable to start correctly for one reason or another. To find out why, execute the following commands in a DOS window:

        c:
        cd "\Program Files\Apache Group\Apache"
        apache
     
    

    (If you don't get the prompt back, hit Control-C to cause Apache to exit.)

    The error you see will probably be one of those preceding this question in the FAQ.

    As of Apache 1.3.14, first check the Windows NT Event Log for Application errors using the Windows NT/2000 Event Viewer program. Any errors that occur prior to opening the Apache error log will be stored here, if Apache is run as a Service on NT or 2000. As with any error, also check your Apache error log.

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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.

    In the SuSE distribution, additional 3rd party authentication modules have been added and activated by default. These modules interfere with the Apache standard modules and cause Basic authentication to fail. Our recommendation is to comment all those modules in /etc/httpd/suse_addmodule.conf and /etc/httpd/suse_loadmodule.conf which are not actually required for running your server.

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15. Why do I have weird entries in my logs asking for default.ida and cmd.exe?

    The host requesting pages from your website and creating those entries is a Windows machine running IIS that has been infected by an Internet worm such as Nimda or Code Red. You can safely ignore these error messages as they do not affect Apache. ApacheWeek has an article with more information.

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16. Why am I getting server restart messages periodically, when I did not restart the server?

    Problem: You are noticing restart messages in your error log, periodically, when you know you did not restart the server yourself:

    [Thu Jun  6 04:02:01 2002] [notice] SIGHUP received.  Attempting to restart
    [Thu Jun  6 04:02:02 2002] [notice] Apache configured -- resuming normal operations
    

    Check your cron jobs to see when/if your server logs are being rotated. Compare the time of rotation to the error message time. If they are the same, you can somewhat safely assume that the restart is due to your server logs being rotated.

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17. Why am I getting "module module-name is not compatible with this version of Apache" messages in my error log?

    Module Magic Number (MMN) is a constant defined in Apache source that is associated with binary compatibility of modules. It is changed when internal Apache structures, function calls and other significant parts of API change in such a way that binary compatibility cannot be guaranteed any more. On MMN change, all third party modules have to be at least recompiled, sometimes even slightly changed in order to work with the new version of Apache.

    If you're getting the above error messages, contact the vendor of the module for the new binary, or compile it if you have access to the source code.

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E. Configuration Questions

1. Why can't I run more than <n> virtual hosts?

   You are probably running into resource limitations in your operating system. The most common limitation is the per-process limit on file descriptors, which is almost always the cause of problems seen when adding virtual hosts. Apache often does not give an intuitive error message because it is normally some library routine (such as gethostbyname()) which needs file descriptors and doesn't complain intelligibly when it can