Apache HTTP Server Version 2.2 (original) (raw)

Please note

This document refers to the 2.2 version of Apache httpd, which is no longer maintained. The active release is documented here. If you have not already upgraded, please follow this link for more information.

You may follow this link to go to the current version of this document.

Apache Core Features

Available Languages: de | en | fr | ja | tr

AcceptFilter Directive

This directive enables operating system specific optimizations for a listening socket by the Protocol type. The basic premise is for the kernel to not send a socket to the server process until either data is received or an entire HTTP Request is buffered. Only FreeBSD's Accept Filters and Linux's more primitiveTCP_DEFER_ACCEPT are currently supported.

The default values on FreeBSD are:

AcceptFilter http httpready AcceptFilter https dataready

The httpready accept filter buffers entire HTTP requests at the kernel level. Once an entire request is received, the kernel then sends it to the server. See the accf_http(9) man page for more details. Since HTTPS requests are encrypted, only the accf_data(9) filter is used.

The default values on Linux are:

AcceptFilter http data AcceptFilter https data

Linux's TCP_DEFER_ACCEPT does not support buffering http requests. Any value besides none will enableTCP_DEFER_ACCEPT on that listener. For more details see the Linux tcp(7) man page.

Using none for an argument will disable any accept filters for that protocol. This is useful for protocols that require a server send data first, such as nntp:

AcceptFilter nntp none

See also

• Protocol

AcceptPathInfo Directive

This directive controls whether requests that contain trailing pathname information that follows an actual filename (or non-existent file in an existing directory) will be accepted or rejected. The trailing pathname information can be made available to scripts in the PATH_INFO environment variable.

For example, assume the location /test/ points to a directory that contains only the single filehere.html. Then requests for/test/here.html/more and/test/nothere.html/more both collect/more as PATH_INFO.

The three possible arguments for theAcceptPathInfo directive are:

Off

A request will only be accepted if it maps to a literal path that exists. Therefore a request with trailing pathname information after the true filename such as/test/here.html/more in the above example will return a 404 NOT FOUND error.

On

A request will be accepted if a leading path component maps to a file that exists. The above example /test/here.html/more will be accepted if/test/here.html maps to a valid file.

Default

The treatment of requests with trailing pathname information is determined by the handler responsible for the request. The core handler for normal files defaults to rejectingPATH_INFO requests. Handlers that serve scripts, such as cgi-script and isapi-handler, generally acceptPATH_INFO by default.

The primary purpose of the AcceptPathInfo directive is to allow you to override the handler's choice of accepting or rejecting PATH_INFO. This override is required, for example, when you use a filter, such as INCLUDES, to generate content based on PATH_INFO. The core handler would usually reject the request, so you can use the following configuration to enable such a script:

<Files "mypaths.shtml"> Options +Includes SetOutputFilter INCLUDES AcceptPathInfo On </Files>

AccessFileName Directive

While processing a request, the server looks for the first existing configuration file from this list of names in every directory of the path to the document, if distributed configuration files are enabled for that directory. For example:

AccessFileName .acl

Before returning the document/usr/local/web/index.html, the server will read/.acl, /usr/.acl,/usr/local/.acl and /usr/local/web/.acl for directives unless they have been disabled with:

<Directory /> AllowOverride None </Directory>

See also

• [AllowOverride](#allowoverride)
• Configuration Files
• .htaccess Files

AddDefaultCharset Directive

This directive specifies a default value for the media type charset parameter (the name of a character encoding) to be added to a response if and only if the response's content-type is eithertext/plain or text/html. This should override any charset specified in the body of the response via a META element, though the exact behavior is often dependent on the user's client configuration. A setting of AddDefaultCharset Off disables this functionality. AddDefaultCharset On enables a default charset of iso-8859-1. Any other value is assumed to be the charset to be used, which should be one of theIANA registered charset values for use in MIME media types. For example:

AddDefaultCharset utf-8

AddDefaultCharset should only be used when all of the text resources to which it applies are known to be in that character encoding and it is too inconvenient to label their charset individually. One such example is to add the charset parameter to resources containing generated content, such as legacy CGI scripts, that might be vulnerable to cross-site scripting attacks due to user-provided data being included in the output. Note, however, that a better solution is to just fix (or delete) those scripts, since setting a default charset does not protect users that have enabled the "auto-detect character encoding" feature on their browser.

See also

• [AddCharset](../mod/mod%5Fmime.html#addcharset)

AddOutputFilterByType Directive

This directive activates a particular output filter for a request depending on the response MIME-type. Because of certain problems discussed below, this directive is deprecated. The same functionality is available using [mod_filter](../mod/mod%5Ffilter.html).

The following example uses the DEFLATE filter, which is provided by [mod_deflate](../mod/mod%5Fdeflate.html). It will compress all output (either static or dynamic) which is labeled astext/html or text/plain before it is sent to the client.

AddOutputFilterByType DEFLATE text/html text/plain

If you want the content to be processed by more than one filter, their names have to be separated by semicolons. It's also possible to use oneAddOutputFilterByType directive for each of these filters.

The configuration below causes all script output labeled astext/html to be processed at first by theINCLUDES filter and then by the DEFLATE filter.

<Location /cgi-bin/> Options Includes AddOutputFilterByType INCLUDES;DEFLATE text/html </Location>

Note

Enabling filters with AddOutputFilterByType may fail partially or completely in some cases. For example, no filters are applied if the MIME-type could not be determined and falls back to the [DefaultType](#defaulttype) setting, even if the [DefaultType](#defaulttype) is the same.

However, if you want to make sure, that the filters will be applied, assign the content type to a resource explicitly, for example with [AddType](../mod/mod%5Fmime.html#addtype) or[ForceType](#forcetype). Setting the content type within a (non-nph) CGI script is also safe.

See also

• [AddOutputFilter](../mod/mod%5Fmime.html#addoutputfilter)
• [SetOutputFilter](#setoutputfilter)
• filters

AllowEncodedSlashes Directive

The AllowEncodedSlashes directive allows URLs which contain encoded path separators (%2F for / and additionally %5C for \ on accordant systems) to be used in the path info.

With the default value, Off, such URLs are refused with a 404 (Not found) error.

With the value On, such URLs are accepted, and encoded slashes are decoded like all other encoded characters.

With the value NoDecode, such URLs are accepted, but encoded slashes are not decoded but left in their encoded state.

Turning AllowEncodedSlashes On is mostly useful when used in conjunction with PATH_INFO.

Note

If encoded slashes are needed in path info, use of NoDecode is strongly recommended as a security measure. Allowing slashes to be decoded could potentially allow unsafe paths.

See also

• [AcceptPathInfo](#acceptpathinfo)

AllowOverride Directive

When the server finds an .htaccess file (as specified by [AccessFileName](#accessfilename)), it needs to know which directives declared in that file can override earlier configuration directives.

Only available in sections

AllowOverride is valid only in[<Directory>](#directory) sections specified without regular expressions, not in [<Location>](#location), [<DirectoryMatch>](#directorymatch) or[<Files>](#files) sections.

When this directive is set to None, then.htaccess files are completely ignored. In this case, the server will not even attempt to read.htaccess files in the filesystem.

When this directive is set to All, then any directive which has the .htaccess Context is allowed in.htaccess files.

The directive-type can be one of the following groupings of directives.

AuthConfig

Allow use of the authorization directives ([AuthDBMGroupFile](../mod/mod%5Fauthz%5Fdbm.html#authdbmgroupfile),[AuthDBMUserFile](../mod/mod%5Fauthn%5Fdbm.html#authdbmuserfile),[AuthGroupFile](../mod/mod%5Fauthz%5Fgroupfile.html#authgroupfile),[AuthName](#authname),[AuthType](#authtype), [AuthUserFile](../mod/mod%5Fauthn%5Ffile.html#authuserfile), [Require](#require), etc.).

FileInfo

Allow use of the directives controlling document types ([DefaultType](#defaulttype), [ErrorDocument](#errordocument), [ForceType](#forcetype), [LanguagePriority](../mod/mod%5Fnegotiation.html#languagepriority),[SetHandler](#sethandler), [SetInputFilter](#setinputfilter), [SetOutputFilter](#setoutputfilter), and[mod_mime](../mod/mod%5Fmime.html) Add* and Remove* directives, etc.), document meta data ([Header](../mod/mod%5Fheaders.html#header), [RequestHeader](../mod/mod%5Fheaders.html#requestheader), [SetEnvIf](../mod/mod%5Fsetenvif.html#setenvif), [SetEnvIfNoCase](../mod/mod%5Fsetenvif.html#setenvifnocase), [BrowserMatch](../mod/mod%5Fsetenvif.html#browsermatch), [CookieExpires](../mod/mod%5Fusertrack.html#cookieexpires), [CookieDomain](../mod/mod%5Fusertrack.html#cookiedomain), [CookieStyle](../mod/mod%5Fusertrack.html#cookiestyle), [CookieTracking](../mod/mod%5Fusertrack.html#cookietracking), [CookieName](../mod/mod%5Fusertrack.html#cookiename)),[mod_rewrite](../mod/mod%5Frewrite.html) directives ([RewriteEngine](../mod/mod%5Frewrite.html#rewriteengine), [RewriteOptions](../mod/mod%5Frewrite.html#rewriteoptions), [RewriteBase](../mod/mod%5Frewrite.html#rewritebase), [RewriteCond](../mod/mod%5Frewrite.html#rewritecond), [RewriteRule](../mod/mod%5Frewrite.html#rewriterule)),[mod_alias](../mod/mod%5Falias.html) directives ([Redirect](../mod/mod%5Falias.html#redirect), [RedirectTemp](../mod/mod%5Falias.html#redirecttemp), [RedirectPermanent](../mod/mod%5Falias.html#redirectpermanent), [RedirectMatch](../mod/mod%5Falias.html#redirectmatch)), and[Action](../mod/mod%5Factions.html#action) from[mod_actions](../mod/mod%5Factions.html).

Indexes

Allow use of the directives controlling directory indexing ([AddDescription](../mod/mod%5Fautoindex.html#adddescription),[AddIcon](../mod/mod%5Fautoindex.html#addicon), [AddIconByEncoding](../mod/mod%5Fautoindex.html#addiconbyencoding),[AddIconByType](../mod/mod%5Fautoindex.html#addiconbytype),[DefaultIcon](../mod/mod%5Fautoindex.html#defaulticon), [DirectoryIndex](../mod/mod%5Fdir.html#directoryindex), FancyIndexing , [HeaderName](../mod/mod%5Fautoindex.html#headername), [IndexIgnore](../mod/mod%5Fautoindex.html#indexignore), [IndexOptions](../mod/mod%5Fautoindex.html#indexoptions), [ReadmeName](../mod/mod%5Fautoindex.html#readmename),etc.).

Limit

Allow use of the directives controlling host access ([Allow](../mod/mod%5Fauthz%5Fhost.html#allow), [Deny](../mod/mod%5Fauthz%5Fhost.html#deny) and [Order](../mod/mod%5Fauthz%5Fhost.html#order)).

Options[=Option,...]

Allow use of the directives controlling specific directory features ([Options](#options) and[XBitHack](../mod/mod%5Finclude.html#xbithack)). An equal sign may be given followed by a comma-separated list, without spaces, of options that may be set using the [Options](#options) command.

Implicit disabling of Options

Even though the list of options that may be used in .htaccess files can be limited with this directive, as long as any [Options](#options) directive is allowed any other inherited option can be disabled by using the non-relative syntax. In other words, this mechanism cannot force a specific option to remain set while allowing any others to be set.

Example:

AllowOverride AuthConfig Indexes

In the example above, all directives that are neither in the groupAuthConfig nor Indexes cause an internal server error.

For security and performance reasons, do not setAllowOverride to anything other than None in your <Directory /> block. Instead, find (or create) the <Directory> block that refers to the directory where you're actually planning to place a.htaccess file.

See also

• [AccessFileName](#accessfilename)
• Configuration Files
• .htaccess Files

AuthName Directive

This directive sets the name of the authorization realm for a directory. This realm is given to the client so that the user knows which username and password to send.AuthName takes a single argument; if the realm name contains spaces, it must be enclosed in quotation marks. It must be accompanied by [AuthType](#authtype) and [Require](#require) directives, and directives such as [AuthUserFile](../mod/mod%5Fauthn%5Ffile.html#authuserfile) and[AuthGroupFile](../mod/mod%5Fauthz%5Fgroupfile.html#authgroupfile) to work.

For example:

AuthName "Top Secret"

The string provided for the AuthName is what will appear in the password dialog provided by most browsers.

See also

• Authentication, Authorization, and Access Control

CGIMapExtension Directive

This directive is used to control how Apache finds the interpreter used to run CGI scripts. For example, settingCGIMapExtension sys:\foo.nlm .foo will cause all CGI script files with a .foo extension to be passed to the FOO interpreter.

ContentDigest Directive

This directive enables the generation ofContent-MD5 headers as defined in RFC1864 respectively RFC2616.

MD5 is an algorithm for computing a "message digest" (sometimes called "fingerprint") of arbitrary-length data, with a high degree of confidence that any alterations in the data will be reflected in alterations in the message digest.

The Content-MD5 header provides an end-to-end message integrity check (MIC) of the entity-body. A proxy or client may check this header for detecting accidental modification of the entity-body in transit. Example header:

Content-MD5: AuLb7Dp1rqtRtxz2m9kRpA==

Note that this can cause performance problems on your server since the message digest is computed on every request (the values are not cached).

Content-MD5 is only sent for documents served by the [core](../mod/core.html), and not by any module. For example, SSI documents, output from CGI scripts, and byte range responses do not have this header.

DefaultType Directive

There will be times when the server is asked to provide a document whose type cannot be determined by its MIME types mappings.

The server SHOULD inform the client of the content-type of the document. If the server is unable to determine this by normal means, it will set it to the configuredDefaultType. For example:

DefaultType image/gif

would be appropriate for a directory which contained many GIF images with filenames missing the .gif extension.

In cases where it can neither be determined by the server nor the administrator (e.g. a proxy), it is preferable to omit the MIME type altogether rather than provide information that may be false. This can be accomplished using

DefaultType None

DefaultType None is only available in httpd-2.2.7 and later.

Note that unlike [ForceType](#forcetype), this directive only provides the default mime-type. All other mime-type definitions, including filename extensions, that might identify the media type will override this default.

Directive

<Directory> and</Directory> are used to enclose a group of directives that will apply only to the named directory, sub-directories of that directory, and the files within the respective directories. Any directive that is allowed in a directory context may be used. Directory-path is either the full path to a directory, or a wild-card string using Unix shell-style matching. In a wild-card string, ? matches any single character, and * matches any sequences of characters. You may also use [] character ranges. None of the wildcards match a `/' character, so <Directory /*/public_html> will not match/home/user/public_html, but <Directory /home/*/public_html> will match. Example:

<Directory /usr/local/httpd/htdocs> Options Indexes FollowSymLinks </Directory>

Be careful with the directory-path arguments: They have to literally match the filesystem path which Apache uses to access the files. Directives applied to a particular<Directory> will not apply to files accessed from that same directory via a different path, such as via different symbolic links.

Regular expressions can also be used, with the addition of the~ character. For example:

<Directory ~ "^/www/[0-9]{3}">

would match directories in /www/ that consisted of three numbers.

If multiple (non-regular expression) <Directory> sections match the directory (or one of its parents) containing a document, then the directives are applied in the order of shortest match first, interspersed with the directives from the .htaccess files. For example, with

`
AllowOverride None

<Directory /home>
AllowOverride FileInfo

`

for access to the document /home/web/dir/doc.html the steps are:

• Apply directive AllowOverride None (disabling .htaccess files).
• Apply directive AllowOverride FileInfo (for directory /home).
• Apply any FileInfo directives in/home/.htaccess, /home/web/.htaccess and/home/web/dir/.htaccess in that order.

Regular expressions are not considered until after all of the normal sections have been applied. Then all of the regular expressions are tested in the order they appeared in the configuration file. For example, with

` <Directory ~ "public_html/.*">

... directives here ...

`

the regular expression section won't be considered until after all normal <Directory>s and.htaccess files have been applied. Then the regular expression will match on /home/abc/public_html/abc and the corresponding <Directory> will be applied.

Note that the default Apache access for<Directory /> is Allow from All. This means that Apache will serve any file mapped from an URL. It is recommended that you change this with a block such as

<Directory /> Order Deny,Allow Deny from All </Directory>

and then override this for directories you_want_ accessible. See the Security Tips page for more details.

The directory sections occur in the httpd.conf file.<Directory> directives cannot nest, and cannot appear in a [<Limit>](#limit) or [<LimitExcept>](#limitexcept) section.

See also

• How , and sections work for an explanation of how these different sections are combined when a request is received

Directive

<DirectoryMatch> and</DirectoryMatch> are used to enclose a group of directives which will apply only to the named directory and_sub-directories of that directory_ (and the files within), the same as [<Directory>](#directory). However, it takes as an argument a regular expression. For example:

<DirectoryMatch "^/www/(.+/)?[0-9]{3}">

would match directories in /www/ that consisted of three numbers.

End-of-line character

The end-of-line character ($) cannot be matched with this directive.

See also

• [<Directory>](#directory) for a description of how regular expressions are mixed in with normal<Directory>s
• How , and sections work for an explanation of how these different sections are combined when a request is received

DocumentRoot Directive

This directive sets the directory from which [httpd](../programs/httpd.html) will serve files. Unless matched by a directive like [Alias](../mod/mod%5Falias.html#alias), the server appends the path from the requested URL to the document root to make the path to the document. Example:

DocumentRoot /usr/web

then an access tohttp://www.my.host.com/index.html refers to/usr/web/index.html. If the directory-path is not absolute then it is assumed to be relative to the [ServerRoot](#serverroot).

The DocumentRoot should be specified without a trailing slash.

See also

• Mapping URLs to Filesystem Locations

EnableMMAP Directive

This directive controls whether the [httpd](../programs/httpd.html) may use memory-mapping if it needs to read the contents of a file during delivery. By default, when the handling of a request requires access to the data within a file -- for example, when delivering a server-parsed file using [mod_include](../mod/mod%5Finclude.html) -- Apache memory-maps the file if the OS supports it.

This memory-mapping sometimes yields a performance improvement. But in some environments, it is better to disable the memory-mapping to prevent operational problems:

• On some multiprocessor systems, memory-mapping can reduce the performance of the [httpd](../programs/httpd.html).
• Deleting or truncating a file while [httpd](../programs/httpd.html) has it memory-mapped can cause [httpd](../programs/httpd.html) to crash with a segmentation fault.

For server configurations that are vulnerable to these problems, you should disable memory-mapping of delivered files by specifying:

EnableMMAP Off

For NFS mounted files, this feature may be disabled explicitly for the offending files by specifying:

<Directory "/path-to-nfs-files"> EnableMMAP Off </Directory>

EnableSendfile Directive

This directive controls whether [httpd](../programs/httpd.html) may use the sendfile support from the kernel to transmit file contents to the client. By default, when the handling of a request requires no access to the data within a file -- for example, when delivering a static file -- Apache uses sendfile to deliver the file contents without ever reading the file if the OS supports it.

This sendfile mechanism avoids separate read and send operations, and buffer allocations. But on some platforms or within some filesystems, it is better to disable this feature to avoid operational problems:

• Some platforms may have broken sendfile support that the build system did not detect, especially if the binaries were built on another box and moved to such a machine with broken sendfile support.
• On Linux the use of sendfile triggers TCP-checksum offloading bugs on certain networking cards when using IPv6.
• On Linux on Itanium, sendfile may be unable to handle files over 2GB in size.
• With a network-mounted [DocumentRoot](#documentroot) (e.g., NFS or SMB), the kernel may be unable to serve the network file through its own cache.

For server configurations that are vulnerable to these problems, you should disable this feature by specifying:

EnableSendfile Off

For NFS or SMB mounted files, this feature may be disabled explicitly for the offending files by specifying:

<Directory "/path-to-nfs-files"> EnableSendfile Off </Directory>

Please note that the per-directory and .htaccess configuration of EnableSendfile is not supported by[mod_disk_cache](../mod/mod%5Fdisk%5Fcache.html). Only global definition of EnableSendfile is taken into account by the module.

ErrorDocument Directive

In the event of a problem or error, Apache can be configured to do one of four things,

1. output a simple hardcoded error message
2. output a customized message
3. internally redirect to a local URL-path to handle the problem/error
4. redirect to an external URL to handle the problem/error

The first option is the default, while options 2-4 are configured using the ErrorDocument directive, which is followed by the HTTP response code and a URL or a message. Apache will sometimes offer additional information regarding the problem/error.

URLs can begin with a slash (/) for local web-paths (relative to the [DocumentRoot](#documentroot)), or be a full URL which the client can resolve. Alternatively, a message can be provided to be displayed by the browser. Examples:

ErrorDocument 500 http://foo.example.com/cgi-bin/tester ErrorDocument 404 /cgi-bin/bad_urls.pl ErrorDocument 401 /subscription_info.html ErrorDocument 403 "Sorry can't allow you access today"

Additionally, the special value default can be used to specify Apache's simple hardcoded message. While not required under normal circumstances, default will restore Apache's simple hardcoded message for configurations that would otherwise inherit an existing ErrorDocument.

` ErrorDocument 404 /cgi-bin/bad_urls.pl

<Directory /web/docs>
ErrorDocument 404 default

`

Note that when you specify an ErrorDocument that points to a remote URL (ie. anything with a method such ashttp in front of it), Apache will send a redirect to the client to tell it where to find the document, even if the document ends up being on the same server. This has several implications, the most important being that the client will not receive the original error status code, but instead will receive a redirect status code. This in turn can confuse web robots and other clients which try to determine if a URL is valid using the status code. In addition, if you use a remote URL in an ErrorDocument 401, the client will not know to prompt the user for a password since it will not receive the 401 status code. Therefore, if you use anErrorDocument 401 directive, then it must refer to a local document.

Microsoft Internet Explorer (MSIE) will by default ignore server-generated error messages when they are "too small" and substitute its own "friendly" error messages. The size threshold varies depending on the type of error, but in general, if you make your error document greater than 512 bytes, then MSIE will show the server-generated error rather than masking it. More information is available in Microsoft Knowledge Base article Q294807.

Although most error messages can be overridden, there are certain circumstances where the internal messages are used regardless of the setting of [ErrorDocument](#errordocument). In particular, if a malformed request is detected, normal request processing will be immediately halted and the internal error message returned. This is necessary to guard against security problems caused by bad requests.

If you are using mod_proxy, you may wish to enable[ProxyErrorOverride](../mod/mod%5Fproxy.html#proxyerroroverride) so that you can provide custom error messages on behalf of your Origin servers. If you don't enable ProxyErrorOverride, Apache will not generate custom error documents for proxied content.

Prior to version 2.0, messages were indicated by prefixing them with a single unmatched double quote character.

See also

• documentation of customizable responses

ErrorLog Directive

The ErrorLog directive sets the name of the file to which the server will log any errors it encounters. If the file-path is not absolute then it is assumed to be relative to the [ServerRoot](#serverroot).

Example

ErrorLog /var/log/httpd/error_log

If the file-path begins with a pipe character "|" then it is assumed to be a command to spawn to handle the error log.

Example

ErrorLog "|/usr/local/bin/httpd_errors"

See the notes on piped logs for more information.

Using syslog instead of a filename enables logging via syslogd(8) if the system supports it. The default is to use syslog facility local7, but you can override this by using the syslog:facility syntax wherefacility can be one of the names usually documented in syslog(1).

Example

ErrorLog syslog:user

SECURITY: See the security tips document for details on why your security could be compromised if the directory where log files are stored is writable by anyone other than the user that starts the server.

Note

When entering a file path on non-Unix platforms, care should be taken to make sure that only forward slashes are used even though the platform may allow the use of back slashes. In general it is a good idea to always use forward slashes throughout the configuration files.

See also

• [LogLevel](#loglevel)
• Apache Log Files

FileETag Directive

The FileETag directive configures the file attributes that are used to create the ETag (entity tag) response header field when the document is based on a static file. (The ETag value is used in cache management to save network bandwidth.) In Apache 1.3.22 and earlier, theETag value was always formed from the file's inode, size, and last-modified time (mtime). TheFileETag directive allows you to choose which of these -- if any -- should be used. The recognized keywords are:

INode

The file's i-node number will be included in the calculation

MTime

The date and time the file was last modified will be included

Size

The number of bytes in the file will be included

All

All available fields will be used. This is equivalent to:

FileETag INode MTime Size

None

If a document is file-based, no ETag field will be included in the response

The INode, MTime, and Size keywords may be prefixed with either + or -, which allow changes to be made to the default setting inherited from a broader scope. Any keyword appearing without such a prefix immediately and completely cancels the inherited setting.

If a directory's configuration includesFileETag INode MTime Size, and a subdirectory's includes FileETag -INode, the setting for that subdirectory (which will be inherited by any sub-subdirectories that don't override it) will be equivalent toFileETag MTime Size.

Warning

Do not change the default for directories or locations that have WebDAV enabled and use [mod_dav_fs](../mod/mod%5Fdav%5Ffs.html) as a storage provider.[mod_dav_fs](../mod/mod%5Fdav%5Ffs.html) uses INode MTime Size as a fixed format for ETag comparisons on conditional requests. These conditional requests will break if the ETag format is changed via FileETag.

Server Side Includes

An ETag is not generated for responses parsed by [mod_include](../mod/mod%5Finclude.html) since the response entity can change without a change of the INode, MTime, or Size of the static file with embedded SSI directives.

Directive

The <Files> directive limits the scope of the enclosed directives by filename. It is comparable to the [<Directory>](#directory) and [<Location>](#location) directives. It should be matched with a </Files> directive. The directives given within this section will be applied to any object with a basename (last component of filename) matching the specified filename. <Files> sections are processed in the order they appear in the configuration file, after the [<Directory>](#directory) sections and.htaccess files are read, but before [<Location>](#location) sections. Note that <Files> can be nested inside [<Directory>](#directory) sections to restrict the portion of the filesystem they apply to.

The filename argument should include a filename, or a wild-card string, where ? matches any single character, and * matches any sequences of characters:

<Files "cat.html"> # Insert stuff that applies to cat.html here

<Files "?at.*"> # This would apply to cat.html, bat.html, hat.php and so on.

Regular expressions can also be used, with the addition of the~ character. For example:

<Files ~ "\.(gif|jpe?g|png)$">

would match most common Internet graphics formats. [<FilesMatch>](#filesmatch) is preferred, however.

Note that unlike [<Directory>](#directory) and [<Location>](#location) sections, <Files> sections can be used inside.htaccess files. This allows users to control access to their own files, at a file-by-file level.

See also

• How , and sections work for an explanation of how these different sections are combined when a request is received

ForceType Directive

When placed into an .htaccess file or a[<Directory>](#directory), or[<Location>](#location) or[<Files>](#files) section, this directive forces all matching files to be served with the content type identification given byMIME-type. For example, if you had a directory full of GIF files, but did not want to label them all with .gif, you might want to use:

ForceType image/gif

Note that unlike [DefaultType](#defaulttype), this directive overrides all mime-type associations, including filename extensions, that might identify the media type.

You can override any ForceType setting by using the value of None:

` # force all files to be image/gif:
<Location /images>
ForceType image/gif

but normal mime-type associations here:

<Location /images/mixed>
ForceType None

`

GprofDir Directive

When the server has been compiled with gprof profiling support,GprofDir causes gmon.out files to be written to the specified directory when the process exits. If the argument ends with a percent symbol ('%'), subdirectories are created for each process id.

This directive currently only works with the [prefork](../mod/prefork.html) MPM.

HostnameLookups Directive

This directive enables DNS lookups so that host names can be logged (and passed to CGIs/SSIs in REMOTE_HOST). The value Double refers to doing double-reverse DNS lookup. That is, after a reverse lookup is performed, a forward lookup is then performed on that result. At least one of the IP addresses in the forward lookup must match the original address. (In "tcpwrappers" terminology this is calledPARANOID.)

Regardless of the setting, when [mod_authz_host](../mod/mod%5Fauthz%5Fhost.html) is used for controlling access by hostname, a double reverse lookup will be performed. This is necessary for security. Note that the result of this double-reverse isn't generally available unless you set HostnameLookups Double. For example, if onlyHostnameLookups On and a request is made to an object that is protected by hostname restrictions, regardless of whether the double-reverse fails or not, CGIs will still be passed the single-reverse result in REMOTE_HOST.

The default is Off in order to save the network traffic for those sites that don't truly need the reverse lookups done. It is also better for the end users because they don't have to suffer the extra latency that a lookup entails. Heavily loaded sites should leave this directiveOff, since DNS lookups can take considerable amounts of time. The utility [logresolve](../programs/logresolve.html), compiled by default to the bin subdirectory of your installation directory, can be used to look up host names from logged IP addresses offline.

HttpProtocolOptions Directive

This directive changes the rules applied to the HTTP Request Line (RFC 7230 §3.1.1) and the HTTP Request Header Fields (RFC 7230 §3.2), which are now applied by default or using the Strict option. Due to legacy modules, applications or custom user-agents which must be deperecated the Unsafe option has been added to revert to the legacy behaviors. These rules are applied prior to request processing, so must be configured at the global or default (first) matching virtual host section, by IP/port interface (and not by name) to be honored.

Prior to the introduction of this directive, the Apache HTTP Server request message parsers were tolerant of a number of forms of input which did not conform to the protocol.RFC 7230 §9.4 Request Splitting and§9.5 Response Smuggling call out only two of the potential risks of accepting non-conformant request messages, whileRFC 7230 §3.5 "Message Parsing Robustness" identify the risks of accepting obscure whitespace and request message formatting. As of the introduction of this directive, all grammer rules of the specification are enforced in the default Strict operating mode, and the strict whitespace suggested by section 3.5 is enforced and cannot be relaxed.

Users are strongly cautioned against toggling the Unsafe mode of operation, particularly on outward-facing, publicly accessible server deployments. If an interface is required for faulty monitoring or other custom service consumers running on an intranet, users should toggle the Unsafe option only on a specific virtual host configured to service their internal private network.

Reviewing the messages logged to the ErrorLog, configured with LogLevel debug level, can help identify such faulty requests along with their origin. Users should pay particular attention to the 400 responses in the access log for invalid requests which were unexpectedly rejected.

RFC 7231 §4.1 "Request Methods" "Overview" requires that origin servers shall respond with an error when an unsupported method is encountered in the request line. This already happens when theLenientMethods option is used, but administrators may wish to toggle the RegisteredMethods option and register any non-standard methods using the RegisterHttpMethod directive, particularly if the Unsafe option has been toggled. The RegisteredMethods option should not be toggled for forward proxy hosts, as the methods supported by the origin servers are unknown to the proxy server.

RFC 2616 §19.6 "Compatibility With Previous Versions" had encouraged HTTP servers to support legacy HTTP/0.9 requests. RFC 7230 superceeds this with "The expectation to support HTTP/0.9 requests has been removed" and offers additional comments in RFC 7230 Appendix A. The Require1.0 option allows the user to remove support of the default Allow0.9 option's behavior.

Directive

The <IfDefine test>...</IfDefine> section is used to mark directives that are conditional. The directives within an <IfDefine> section are only processed if the test is true. If test is false, everything between the start and end markers is ignored.

The test in the <IfDefine> section directive can be one of two forms:

• parameter-name
• !parameter-name

In the former case, the directives between the start and end markers are only processed if the parameter namedparameter-name is defined. The second format reverses the test, and only processes the directives ifparameter-name is not defined.

The parameter-name argument is a define as given on the [httpd](../programs/httpd.html) command line via -Dparameter- , at the time the server was started.

<IfDefine> sections are nest-able, which can be used to implement simple multiple-parameter tests. Example:

` httpd -DReverseProxy -DUseCache -DMemCache ...

httpd.conf

`

Directive

The <IfModule test>...</IfModule> section is used to mark directives that are conditional on the presence of a specific module. The directives within an <IfModule> section are only processed if the test is true. If test is false, everything between the start and end markers is ignored.

The test in the <IfModule> section directive can be one of two forms:

• module
• !module

In the former case, the directives between the start and end markers are only processed if the module named module is included in Apache -- either compiled in or dynamically loaded using [LoadModule](../mod/mod%5Fso.html#loadmodule). The second format reverses the test, and only processes the directives if module isnot included.

The module argument can be either the module identifier or the file name of the module, at the time it was compiled. For example,rewrite_module is the identifier andmod_rewrite.c is the file name. If a module consists of several source files, use the name of the file containing the stringSTANDARD20_MODULE_STUFF.

<IfModule> sections are nest-able, which can be used to implement simple multiple-module tests.

This section should only be used if you need to have one configuration file that works whether or not a specific module is available. In normal operation, directives need not be placed in <IfModule> sections.

Include Directive

This directive allows inclusion of other configuration files from within the server configuration files.

Shell-style (fnmatch()) wildcard characters can be used to include several files at once, in alphabetical order. In addition, if Include points to a directory, rather than a file, Apache will read all files in that directory and any subdirectory. But including entire directories is not recommended, because it is easy to accidentally leave temporary files in a directory that can cause [httpd](../programs/httpd.html) to fail.

The file path specified may be an absolute path, or may be relative to the [ServerRoot](#serverroot) directory.

Examples:

Include /usr/local/apache2/conf/ssl.conf Include /usr/local/apache2/conf/vhosts/*.conf

Or, providing paths relative to your [ServerRoot](#serverroot) directory:

Include conf/ssl.conf Include conf/vhosts/*.conf

See also

• [apachectl](../programs/apachectl.html)

KeepAlive Directive

The Keep-Alive extension to HTTP/1.0 and the persistent connection feature of HTTP/1.1 provide long-lived HTTP sessions which allow multiple requests to be sent over the same TCP connection. In some cases this has been shown to result in an almost 50% speedup in latency times for HTML documents with many images. To enable Keep-Alive connections, setKeepAlive On.

For HTTP/1.0 clients, Keep-Alive connections will only be used if they are specifically requested by a client. In addition, a Keep-Alive connection with an HTTP/1.0 client can only be used when the length of the content is known in advance. This implies that dynamic content such as CGI output, SSI pages, and server-generated directory listings will generally not use Keep-Alive connections to HTTP/1.0 clients. For HTTP/1.1 clients, persistent connections are the default unless otherwise specified. If the client requests it, chunked encoding will be used in order to send content of unknown length over persistent connections.

When a client uses a Keep-Alive connection, it will be counted as a single "request" for the MaxRequestsPerChild directive, regardless of how many requests are sent using the connection.

See also

• [MaxKeepAliveRequests](#maxkeepaliverequests)

KeepAliveTimeout Directive

The number of seconds Apache will wait for a subsequent request before closing the connection. Once a request has been received, the timeout value specified by the[Timeout](#timeout) directive applies.

Setting KeepAliveTimeout to a high value may cause performance problems in heavily loaded servers. The higher the timeout, the more server processes will be kept occupied waiting on connections with idle clients.

In a name-based virtual host context, the value of the first defined virtual host (the default host) in a set of [NameVirtualHost](#namevirtualhost) will be used. The other values will be ignored.

Directive

Access controls are normally effective forall access methods, and this is the usual desired behavior. In the general case, access control directives should not be placed within a<Limit> section.

The purpose of the <Limit> directive is to restrict the effect of the access controls to the nominated HTTP methods. For all other methods, the access restrictions that are enclosed in the <Limit> bracket will have no effect. The following example applies the access control only to the methods POST, PUT, andDELETE, leaving all other methods unprotected:

<Limit POST PUT DELETE> Require valid-user </Limit>

The method names listed can be one or more of: GET,POST, PUT, DELETE,CONNECT, OPTIONS,PATCH, PROPFIND, PROPPATCH,MKCOL, COPY, MOVE,LOCK, and UNLOCK. The method name is case-sensitive. If GET is used, it will also restrict HEAD requests. The TRACE method cannot be limited.

A [<LimitExcept>](#limitexcept) section should always be used in preference to a [<Limit>](#limit) section when restricting access, since a [<LimitExcept>](#limitexcept) section provides protection against arbitrary methods.

Directive

<LimitExcept> and</LimitExcept> are used to enclose a group of access control directives which will then apply to any HTTP access method not listed in the arguments; i.e., it is the opposite of a [<Limit>](#limit) section and can be used to control both standard and nonstandard/unrecognized methods. See the documentation for [<Limit>](#limit) for more details.

For example:

<LimitExcept POST GET> Require valid-user </LimitExcept>

LimitInternalRecursion Directive

An internal redirect happens, for example, when using the [Action](../mod/mod%5Factions.html#action) directive, which internally redirects the original request to a CGI script. A subrequest is Apache's mechanism to find out what would happen for some URI if it were requested. For example, [mod_dir](../mod/mod%5Fdir.html) uses subrequests to look for the files listed in the [DirectoryIndex](../mod/mod%5Fdir.html#directoryindex) directive.

LimitInternalRecursion prevents the server from crashing when entering an infinite loop of internal redirects or subrequests. Such loops are usually caused by misconfigurations.

The directive stores two different limits, which are evaluated on per-request basis. The first number is the maximum number of internal redirects that may follow each other. The second number determines how deeply subrequests may be nested. If you specify only onenumber, it will be assigned to both limits.

Example

LimitInternalRecursion 5

LimitRequestBody Directive

This directive specifies the number of bytes from 0 (meaning unlimited) to 2147483647 (2GB) that are allowed in a request body.

The LimitRequestBody directive allows the user to set a limit on the allowed size of an HTTP request message body within the context in which the directive is given (server, per-directory, per-file or per-location). If the client request exceeds that limit, the server will return an error response instead of servicing the request. The size of a normal request message body will vary greatly depending on the nature of the resource and the methods allowed on that resource. CGI scripts typically use the message body for retrieving form information. Implementations of the PUT method will require a value at least as large as any representation that the server wishes to accept for that resource.

This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks.

If, for example, you are permitting file upload to a particular location and wish to limit the size of the uploaded file to 100K, you might use the following directive:

LimitRequestBody 102400

Note: not applicable to proxy requests.

LimitRequestFields Directive

Number is an integer from 0 (meaning unlimited) to 32767. The default value is defined by the compile-time constant DEFAULT_LIMIT_REQUEST_FIELDS (100 as distributed).

The LimitRequestFields directive allows the server administrator to modify the limit on the number of request header fields allowed in an HTTP request. A server needs this value to be larger than the number of fields that a normal client request might include. The number of request header fields used by a client rarely exceeds 20, but this may vary among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation. Optional HTTP extensions are often expressed using request header fields.

This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks. The value should be increased if normal clients see an error response from the server that indicates too many fields were sent in the request.

For example:

LimitRequestFields 50

Warning

When name-based virtual hosting is used, the value for this directive is taken from the default (first-listed) virtual host for theNameVirtualHost the connection was mapped to.

LimitRequestFieldSize Directive

This directive specifies the number of bytes that will be allowed in an HTTP request header.

The LimitRequestFieldSize directive allows the server administrator to set the limit on the allowed size of an HTTP request header field. A server needs this value to be large enough to hold any one header field from a normal client request. The size of a normal request header field will vary greatly among different client implementations, often depending upon the extent to which a user has configured their browser to support detailed content negotiation. SPNEGO authentication headers can be up to 12392 bytes.

This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks.

For example:

LimitRequestFieldSize 4094

Under normal conditions, the value should not be changed from the default.

Warning

When name-based virtual hosting is used, the value for this directive is taken from the default (first-listed) virtual host for theNameVirtualHost the connection was mapped to.

LimitRequestLine Directive

This directive sets the number of bytes that will be allowed on the HTTP request-line.

The LimitRequestLine directive allows the server administrator to set the limit on the allowed size of a client's HTTP request-line. Since the request-line consists of the HTTP method, URI, and protocol version, theLimitRequestLine directive places a restriction on the length of a request-URI allowed for a request on the server. A server needs this value to be large enough to hold any of its resource names, including any information that might be passed in the query part of a GET request.

This directive gives the server administrator greater control over abnormal client request behavior, which may be useful for avoiding some forms of denial-of-service attacks.

For example:

LimitRequestLine 4094

Under normal conditions, the value should not be changed from the default.

Warning

When name-based virtual hosting is used, the value for this directive is taken from the default (first-listed) virtual host for theNameVirtualHost the connection was mapped to.

Directive

The <Location> directive limits the scope of the enclosed directives by URL. It is similar to the[<Directory>](#directory) directive, and starts a subsection which is terminated with a</Location> directive. <Location> sections are processed in the order they appear in the configuration file, after the [<Directory>](#directory) sections and.htaccess files are read, and after the [<Files>](#files) sections.

<Location> sections operate completely outside the filesystem. This has several consequences. Most importantly, <Location> directives should not be used to control access to filesystem locations. Since several different URLs may map to the same filesystem location, such access controls may by circumvented.

The enclosed directives will be applied to the request if the path component of the URL meets any of the following criteria:

• The specified location matches exactly the path component of the URL.
• The specified location, which ends in a forward slash, is a prefix of the path component of the URL (treated as a context root).
• The specified location, with the addition of a trailing slash, is a prefix of the path component of the URL (also treated as a context root).

In the example below, where no trailing slash is used, requests to /private1, /private1/ and /private1/file.txt will have the enclosed directives applied, but /private1other would not.

<Location /private1> ...

In the example below, where a trailing slash is used, requests to /private2/ and /private2/file.txt will have the enclosed directives applied, but /private2 and /private2other would not.

<Location /private2_/_> ...

When to use <Location>

Use <Location> to apply directives to content that lives outside the filesystem. For content that lives in the filesystem, use [<Directory>](#directory) and [<Files>](#files). An exception is<Location />, which is an easy way to apply a configuration to the entire server.

For all origin (non-proxy) requests, the URL to be matched is a URL-path of the form /path/. No scheme, hostname, port, or query string may be included. For proxy requests, the URL to be matched is of the formscheme://servername/path, and you must include the prefix.

The URL may use wildcards. In a wild-card string, ? matches any single character, and * matches any sequences of characters. Neither wildcard character matches a / in the URL-path.

Regular expressions can also be used, with the addition of the~ character. For example:

<Location ~ "/(extra|special)/data">

would match URLs that contained the substring /extra/data or /special/data. The directive [<LocationMatch>](#locationmatch) behaves identical to the regex version of <Location>.

The <Location> functionality is especially useful when combined with the[SetHandler](#sethandler) directive. For example, to enable status requests but allow them only from browsers at example.com, you might use:

<Location /status> SetHandler server-status Order Deny,Allow Deny from all Allow from .example.com </Location>

Note about / (slash)

The slash character has special meaning depending on where in a URL it appears. People may be used to its behavior in the filesystem where multiple adjacent slashes are frequently collapsed to a single slash (i.e., /home///foo is the same as/home/foo). In URL-space this is not necessarily true. The [<LocationMatch>](#locationmatch) directive and the regex version of <Location> require you to explicitly specify multiple slashes if that is your intention.

For example, <LocationMatch ^/abc> would match the request URL /abc but not the request URL //abc. The (non-regex) <Location> directive behaves similarly when used for proxy requests. But when (non-regex) <Location> is used for non-proxy requests it will implicitly match multiple slashes with a single slash. For example, if you specify <Location /abc/def> and the request is to /abc//def then it will match.

See also

• How , and sections work for an explanation of how these different sections are combined when a request is received

Directive

The <LocationMatch> directive limits the scope of the enclosed directives by URL, in an identical manner to [<Location>](#location). However, it takes a regular expression as an argument instead of a simple string. For example:

<LocationMatch "/(extra|special)/data">

would match URLs that contained the substring /extra/data or /special/data.

See also

• How , and sections work for an explanation of how these different sections are combined when a request is received

LogLevel Directive

LogLevel adjusts the verbosity of the messages recorded in the error logs (see [ErrorLog](#errorlog) directive). The followinglevels are available, in order of decreasing significance:

When a particular level is specified, messages from all other levels of higher significance will be reported as well.E.g., when LogLevel info is specified, then messages with log levels of notice andwarn will also be posted.

Using a level of at least crit is recommended.

For example:

LogLevel notice

Note

When logging to a regular file, messages of the levelnotice cannot be suppressed and thus are always logged. However, this doesn't apply when logging is done using syslog.

MaxKeepAliveRequests Directive

The MaxKeepAliveRequests directive limits the number of requests allowed per connection when[KeepAlive](#keepalive) is on. If it is set to 0, unlimited requests will be allowed. We recommend that this setting be kept to a high value for maximum server performance.

For example:

MaxKeepAliveRequests 500

MaxRanges Directive

The MaxRanges directive limits the number of HTTP ranges the server is willing to return to the client. If more ranges than permitted are requested, the complete resource is returned instead.

default

Limits the number of ranges to a compile-time default of 200.

none

Range headers are ignored.

unlimited

The server does not limit the number of ranges it is willing to satisfy.

number-of-ranges

A positive number representing the maximum number of ranges the server is willing to satisfy.

MergeTrailers Directive

This directive controls whether HTTP trailers are copied into the internal representation of HTTP headers. This merging occurs when the request body has been completely consumed, long after most header processing would have a chance to examine or modify request headers.

This option is provided for compatibility with releases prior to 2.2.28, where trailers were always merged.

NameVirtualHost Directive

The NameVirtualHost directive is a required directive if you want to configure name-based virtual hosts.

Although addr can be hostname it is recommended that you always use an IP address and a port, e.g.

NameVirtualHost 111.22.33.44:80

With the NameVirtualHost directive you specify the IP address on which the server will receive requests for the name-based virtual hosts. This will usually be the address to which your name-based virtual host names resolve. In cases where a firewall or other proxy receives the requests and forwards them on a different IP address to the server, you must specify the IP address of the physical interface on the machine which will be servicing the requests. If you have multiple name-based hosts on multiple addresses, repeat the directive for each address.

Note

Note, that the "main server" and any _default_ servers will never be served for a request to aNameVirtualHost IP address (unless for some reason you specify NameVirtualHost but then don't define any VirtualHosts for that address).

Optionally you can specify a port number on which the name-based virtual hosts should be used, e.g.

NameVirtualHost 111.22.33.44:8080

IPv6 addresses must be enclosed in square brackets, as shown in the following example:

NameVirtualHost [2001:db8::a00:20ff:fea7:ccea]:8080

To receive requests on all interfaces, you can use an argument of*:80, or, if you are listening on multiple ports and really want the server to respond on all of them with a particular set of virtual hosts, *

NameVirtualHost *:80

Argument to <VirtualHost> directive

Note that the argument to the <VirtualHost> directive must exactly match the argument to the NameVirtualHost directive.

` NameVirtualHost 1.2.3.4:80
<VirtualHost 1.2.3.4:80>

...

See also

• Virtual Hosts documentation

Options Directive

The Options directive controls which server features are available in a particular directory.

option can be set to None, in which case none of the extra features are enabled, or one or more of the following:

All

All options except for MultiViews. This is the default setting.

ExecCGI

Execution of CGI scripts using [mod_cgi](../mod/mod%5Fcgi.html) is permitted.

FollowSymLinks

The server will follow symbolic links in this directory.

Even though the server follows the symlink it does not change the pathname used to match against [<Directory>](#directory) sections.

The FollowSymLinks andSymLinksIfOwnerMatch [Options](#options) work only in [<Directory>](#directory) sections or.htaccess files.

Omitting this option should not be considered a security restriction, since symlink testing is subject to race conditions that make it circumventable.

Includes

Server-side includes provided by [mod_include](../mod/mod%5Finclude.html) are permitted.

IncludesNOEXEC

Server-side includes are permitted, but the #exec cmd and #exec cgi are disabled. It is still possible to #include virtual CGI scripts from[ScriptAlias](../mod/mod%5Falias.html#scriptalias)ed directories.

Indexes

If a URL which maps to a directory is requested and there is no [DirectoryIndex](../mod/mod%5Fdir.html#directoryindex) (e.g., index.html) in that directory, then[mod_autoindex](../mod/mod%5Fautoindex.html) will return a formatted listing of the directory.

MultiViews

Content negotiated "MultiViews" are allowed using[mod_negotiation](../mod/mod%5Fnegotiation.html).

SymLinksIfOwnerMatch

The server will only follow symbolic links for which the target file or directory is owned by the same user id as the link.

Note

The FollowSymLinks andSymLinksIfOwnerMatch [Options](#options) work only in [<Directory>](#directory) sections or.htaccess files.

This option should not be considered a security restriction, since symlink testing is subject to race conditions that make it circumventable.

Normally, if multiple Options could apply to a directory, then the most specific one is used and others are ignored; the options are not merged. (See how sections are merged.) However if all the options on theOptions directive are preceded by a+ or - symbol, the options are merged. Any options preceded by a + are added to the options currently in force, and any options preceded by a- are removed from the options currently in force.

Warning

Mixing Options with a + or- with those without is not valid syntax and is likely to cause unexpected results.

For example, without any + and - symbols:

` <Directory /web/docs>
Options Indexes FollowSymLinks

<Directory /web/docs/spec>
Options Includes

`

then only Includes will be set for the/web/docs/spec directory. However if the secondOptions directive uses the + and- symbols:

` <Directory /web/docs>
Options Indexes FollowSymLinks

<Directory /web/docs/spec>
Options +Includes -Indexes

`

then the options FollowSymLinks andIncludes are set for the /web/docs/spec directory.

Note

Using -IncludesNOEXEC or-Includes disables server-side includes completely regardless of the previous setting.

The default in the absence of any other settings isAll.

Protocol Directive

This directive specifies the protocol used for a specific listening socket. The protocol is used to determine which module should handle a request and to apply protocol specific optimizations with the AcceptFilter directive.

You only need to set the protocol if you are running on non-standard ports; otherwise, http is assumed for port 80 and https for port 443.

For example, if you are running https on a non-standard port, specify the protocol explicitly:

Protocol https

You can also specify the protocol using the [Listen](../mod/mpm%5Fcommon.html#listen) directive.

See also

• AcceptFilter
• [Listen](../mod/mpm%5Fcommon.html#listen)

RegisterHttpMethod Directive

HTTP Methods that are not conforming to the relvant RFCs are normally rejected by request processing in Apache HTTPD. To avoid this, modules can register non-standard HTTP methods they support. The RegisterHttpMethod allows to register such methods manually. This can be useful for if such methods are forwared for external processing, e.g. to a CGI script.

Require Directive

This directive selects which authenticated users can access a resource. Multiple instances of this directive are combined with a logical "OR", such that a user matching any Require line is granted access. The restrictions are processed by authorization modules. Some of the allowed syntaxes provided by[mod_authz_user](../mod/mod%5Fauthz%5Fuser.html) and[mod_authz_groupfile](../mod/mod%5Fauthz%5Fgroupfile.html) are:

Require user userid [userid] ...

Only the named users can access the resource.

Require group group-name [group-name] ...

Only users in the named groups can access the resource.

Require valid-user

All valid users can access the resource.

Other authorization modules that implement require options include [mod_authnz_ldap](../mod/mod%5Fauthnz%5Fldap.html),[mod_authz_dbm](../mod/mod%5Fauthz%5Fdbm.html), and[mod_authz_owner](../mod/mod%5Fauthz%5Fowner.html).

Require must be accompanied by[AuthName](#authname) and [AuthType](#authtype) directives, and directives such as [AuthUserFile](../mod/mod%5Fauthn%5Ffile.html#authuserfile) and [AuthGroupFile](../mod/mod%5Fauthz%5Fgroupfile.html#authgroupfile) (to define users and groups) in order to work correctly. Example:

AuthType Basic AuthName "Restricted Resource" AuthUserFile /web/users AuthGroupFile /web/groups Require group admin

Access controls which are applied in this way are effective forall methods. This is what is normally desired. If you wish to apply access controls only to specific methods, while leaving other methods unprotected, then place the Require statement into a[<Limit>](#limit) section.

If Require is used together with the [Allow](../mod/mod%5Fauthz%5Fhost.html#allow) or[Deny](../mod/mod%5Fauthz%5Fhost.html#deny) directives, then the interaction of these restrictions is controlled by the [Satisfy](#satisfy) directive.

Multiple Require directives do operate as logical "OR", but some underlying authentication modules may require an explicit configuration to let authentication be chained to others. This is typically the case with [mod_authnz_ldap](../mod/mod%5Fauthnz%5Fldap.html), which exports the AuthzLDAPAuthoritative in that intent.

Removing controls in subdirectories

The following example shows how to use the [Satisfy](#satisfy) directive to disable access controls in a subdirectory of a protected directory. This technique should be used with caution, because it will also disable any access controls imposed by[mod_authz_host](../mod/mod%5Fauthz%5Fhost.html).

` <Directory /path/to/protected/>
Require user david

<Directory /path/to/protected/unprotected>

All access controls and authentication are disabled

in this directory

Satisfy Any
Allow from all

`

See also

• Authentication and Authorization
• Access Control
• [Satisfy](#satisfy)
• [mod_authz_host](../mod/mod%5Fauthz%5Fhost.html)

RLimitCPU Directive

Takes 1 or 2 parameters. The first parameter sets the soft resource limit for all processes and the second parameter sets the maximum resource limit. Either parameter can be a number, or max to indicate to the server that the limit should be set to the maximum allowed by the operating system configuration. Raising the maximum resource limit requires that the server is running as root or in the initial startup phase.

This applies to processes forked from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked from the Apache parent, such as piped logs.

CPU resource limits are expressed in seconds per process.

See also

• [RLimitMEM](#rlimitmem)
• [RLimitNPROC](#rlimitnproc)

RLimitMEM Directive

Takes 1 or 2 parameters. The first parameter sets the soft resource limit for all processes and the second parameter sets the maximum resource limit. Either parameter can be a number, or max to indicate to the server that the limit should be set to the maximum allowed by the operating system configuration. Raising the maximum resource limit requires that the server is running as root or in the initial startup phase.

This applies to processes forked from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked from the Apache parent, such as piped logs.

Memory resource limits are expressed in bytes per process.

See also

• [RLimitCPU](#rlimitcpu)
• [RLimitNPROC](#rlimitnproc)

RLimitNPROC Directive

Takes 1 or 2 parameters. The first parameter sets the soft resource limit for all processes, and the second parameter sets the maximum resource limit. Either parameter can be a number, or max to indicate to the server that the limit should be set to the maximum allowed by the operating system configuration. Raising the maximum resource limit requires that the server is running as root or in the initial startup phase.

This applies to processes forked from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked from the Apache parent, such as piped logs.

Process limits control the number of processes per user.

Note

If CGI processes are not running under user ids other than the web server user id, this directive will limit the number of processes that the server itself can create. Evidence of this situation will be indicated by**cannot fork** messages in theerror_log.

See also

• [RLimitMEM](#rlimitmem)
• [RLimitCPU](#rlimitcpu)

Satisfy Directive

Access policy if both [Allow](../mod/mod%5Fauthz%5Fhost.html#allow) and [Require](#require) used. The parameter can be either All or Any. This directive is only useful if access to a particular area is being restricted by both username/password and client host address. In this case the default behavior (All) is to require that the client passes the address access restriction and enters a valid username and password. With the Any option the client will be granted access if they either pass the host restriction or enter a valid username and password. This can be used to password restrict an area, but to let clients from particular addresses in without prompting for a password.

For example, if you wanted to let people on your network have unrestricted access to a portion of your website, but require that people outside of your network provide a password, you could use a configuration similar to the following:

Require valid-user Order allow,deny Allow from 192.168.1 Satisfy Any

Since version 2.0.51 Satisfy directives can be restricted to particular methods by [<Limit>](#limit) and [<LimitExcept>](#limitexcept) sections.

See also

• [Allow](../mod/mod%5Fauthz%5Fhost.html#allow)
• [Require](#require)

ScriptInterpreterSource Directive

This directive is used to control how Apache finds the interpreter used to run CGI scripts. The default setting isScript. This causes Apache to use the interpreter pointed to by the shebang line (first line, starting with #!) in the script. On Win32 systems this line usually looks like:

#!C:/Perl/bin/perl.exe

or, if perl is in the PATH, simply:

#!perl

Setting ScriptInterpreterSource Registry will cause the Windows Registry tree HKEY_CLASSES_ROOT to be searched using the script file extension (e.g., .pl) as a search key. The command defined by the registry subkeyShell\ExecCGI\Command or, if it does not exist, by the subkeyShell\Open\Command is used to open the script file. If the registry keys cannot be found, Apache falls back to the behavior of theScript option.

For example, the registry setting to have a script with the .pl extension processed via perl would be:

`HKEY_CLASSES_ROOT\.pl\Shell\ExecCGI\Command\(Default) => C:\Perl\bin\perl.exe -wT`

Security

Be careful when using ScriptInterpreterSource Registry with [ScriptAlias](../mod/mod%5Falias.html#scriptalias)'ed directories, because Apache will try to execute every file within this directory. The Registry setting may cause undesired program calls on files which are typically not executed. For example, the default open command on .htm files on most Windows systems will execute Microsoft Internet Explorer, so any HTTP request for an .htm file existing within the script directory would start the browser in the background on the server. This is a good way to crash your system within a minute or so.

The option Registry-Strict which is new in Apache 2.0 does the same thing as Registry but uses only the subkey Shell\ExecCGI\Command. TheExecCGI key is not a common one. It must be configured manually in the windows registry and hence prevents accidental program calls on your system.

ServerAdmin Directive

The ServerAdmin sets the contact address that the server includes in any error messages it returns to the client. If the httpd doesn't recognize the supplied argument as an URL, it assumes, that it's an email-address and prepends it withmailto: in hyperlink targets. However, it's recommended to actually use an email address, since there are a lot of CGI scripts that make that assumption. If you want to use an URL, it should point to another server under your control. Otherwise users may not be able to contact you in case of errors.

It may be worth setting up a dedicated address for this, e.g.

ServerAdmin www-admin@foo.example.com

as users do not always mention that they are talking about the server!

ServerAlias Directive

The ServerAlias directive sets the alternate names for a host, for use with name-based virtual hosts. TheServerAlias may include wildcards, if appropriate.

` <VirtualHost *:80>
ServerName server.domain.com
ServerAlias server server2.domain.com server2
ServerAlias *.example.com
UseCanonicalName Off

...

`

Name-based virtual hosts for the best-matching set of [<virtualhost>](#virtualhost)s are processed in the order they appear in the configuration. The first matching [ServerName](#servername) or [ServerAlias](#serveralias) is used, with no different precedence for wildcards (nor for ServerName vs. ServerAlias).

The complete list of names in the VirtualHost directive are treated just like a (non wildcard)ServerAlias.

See also

• [UseCanonicalName](#usecanonicalname)
• Apache Virtual Host documentation

ServerName Directive

The ServerName directive sets the request scheme, hostname and port that the server uses to identify itself. This is used when creating redirection URLs.

Additionally, ServerName is used (possibly in conjunction with ServerAlias) to uniquely identify a virtual host, when using name-based virtual hosts.

For example, if the name of the machine hosting the web server is simple.example.com, but the machine also has the DNS alias www.example.com and you wish the web server to be so identified, the following directive should be used:

ServerName www.example.com

If no ServerName is specified, then the server attempts to deduce the hostname by performing a reverse lookup on the IP address. If no port is specified in theServerName, then the server will use the port from the incoming request. For optimal reliability and predictability, you should specify an explicit hostname and port using the ServerName directive.

If you are using name-based virtual hosts, the ServerName inside a[<VirtualHost>](#virtualhost) section specifies what hostname must appear in the request'sHost: header to match this virtual host.

Sometimes, the server runs behind a device that processes SSL, such as a reverse proxy, load balancer or SSL offload appliance. When this is the case, specify thehttps:// scheme and the port number to which the clients connect in the ServerName directive to make sure that the server generates the correct self-referential URLs.

See the description of the[UseCanonicalName](#usecanonicalname) and[UseCanonicalPhysicalPort](#usecanonicalphysicalport) directives for settings which determine whether self-referential URLs (e.g., by the[mod_dir](../mod/mod%5Fdir.html) module) will refer to the specified port, or to the port number given in the client's request.

See also

• Issues Regarding DNS and Apache
• Apache virtual host documentation
• [UseCanonicalName](#usecanonicalname)
• [UseCanonicalPhysicalPort](#usecanonicalphysicalport)
• [NameVirtualHost](#namevirtualhost)
• [ServerAlias](#serveralias)

ServerRoot Directive

The ServerRoot directive sets the directory in which the server lives. Typically it will contain the subdirectories conf/ and logs/. Relative paths in other configuration directives (such as [Include](#include) or [LoadModule](../mod/mod%5Fso.html#loadmodule), for example) are taken as relative to this directory.

Example

ServerRoot /home/httpd

See also

• the -d option to httpd
• the security tips for information on how to properly set permissions on the ServerRoot

ServerSignature Directive

The ServerSignature directive allows the configuration of a trailing footer line under server-generated documents (error messages, [mod_proxy](../mod/mod%5Fproxy.html) ftp directory listings, [mod_info](../mod/mod%5Finfo.html) output, ...). The reason why you would want to enable such a footer line is that in a chain of proxies, the user often has no possibility to tell which of the chained servers actually produced a returned error message.

The Off setting, which is the default, suppresses the footer line (and is therefore compatible with the behavior of Apache-1.2 and below). The On setting simply adds a line with the server version number and [ServerName](#servername) of the serving virtual host, and the EMail setting additionally creates a "mailto:" reference to the [ServerAdmin](#serveradmin) of the referenced document.

After version 2.0.44, the details of the server version number presented are controlled by the [ServerTokens](#servertokens) directive.

See also

• [ServerTokens](#servertokens)

ServerTokens Directive

This directive controls whether Server response header field which is sent back to clients includes a description of the generic OS-type of the server as well as information about compiled-in modules.

ServerTokens Prod[uctOnly]

Server sends (e.g.): Server: Apache

ServerTokens Major

Server sends (e.g.): Server: Apache/2

ServerTokens Minor

Server sends (e.g.): Server: Apache/2.0

ServerTokens Min[imal]

Server sends (e.g.): Server: Apache/2.0.41

ServerTokens OS

Server sends (e.g.): Server: Apache/2.0.41 (Unix)

ServerTokens Full (or not specified)

Server sends (e.g.): Server: Apache/2.0.41 (Unix) PHP/4.2.2 MyMod/1.2

This setting applies to the entire server and cannot be enabled or disabled on a virtualhost-by-virtualhost basis.

After version 2.0.44, this directive also controls the information presented by the [ServerSignature](#serversignature) directive.

See also

• [ServerSignature](#serversignature)

SetHandler Directive

When placed into an .htaccess file or a[<Directory>](#directory) or[<Location>](#location) section, this directive forces all matching files to be parsed through the handler given byhandler-name. For example, if you had a directory you wanted to be parsed entirely as imagemap rule files, regardless of extension, you might put the following into an.htaccess file in that directory:

SetHandler imap-file

Another example: if you wanted to have the server display a status report whenever a URL ofhttp://servername/status was called, you might put the following into httpd.conf:

<Location /status> SetHandler server-status </Location>

You can override an earlier defined SetHandler directive by using the value None.

See also

• [AddHandler](../mod/mod%5Fmime.html#addhandler)

SetInputFilter Directive

The SetInputFilter directive sets the filter or filters which will process client requests and POST input when they are received by the server. This is in addition to any filters defined elsewhere, including the[AddInputFilter](../mod/mod%5Fmime.html#addinputfilter) directive.

If more than one filter is specified, they must be separated by semicolons in the order in which they should process the content.

See also

• Filters documentation

SetOutputFilter Directive

The SetOutputFilter directive sets the filters which will process responses from the server before they are sent to the client. This is in addition to any filters defined elsewhere, including the[AddOutputFilter](../mod/mod%5Fmime.html#addoutputfilter) directive.

For example, the following configuration will process all files in the /www/data/ directory for server-side includes.

<Directory /www/data/> SetOutputFilter INCLUDES </Directory>

If more than one filter is specified, they must be separated by semicolons in the order in which they should process the content.

See also

• Filters documentation

Suexec Directive

When On, startup will fail if the suexec binary doesn't exist or has an invalid owner or file mode.

When Off, suEXEC will be disabled even if the suexec binary exists and has a valid owner and file mode.

TimeOut Directive

The TimeOut directive defines the length of time Apache will wait for I/O in various circumstances:

1. When reading data from the client, the length of time to wait for a TCP packet to arrive if the read buffer is empty.
2. When writing data to the client, the length of time to wait for an acknowledgement of a packet if the send buffer is full.
3. In [mod_cgi](../mod/mod%5Fcgi.html), the length of time to wait for output from a CGI script.
4. In [mod_ext_filter](../mod/mod%5Fext%5Ffilter.html), the length of time to wait for output from a filtering process.
5. In [mod_proxy](../mod/mod%5Fproxy.html), the default timeout value if[ProxyTimeout](../mod/mod%5Fproxy.html#proxytimeout) is not configured.

TraceEnable Directive

This directive overrides the behavior of TRACE for both the core server and [mod_proxy](../mod/mod%5Fproxy.html). The defaultTraceEnable on permits TRACE requests per RFC 2616, which disallows any request body to accompany the request.TraceEnable off causes the core server and[mod_proxy](../mod/mod%5Fproxy.html) to return a 405 (Method not allowed) error to the client.

Finally, for testing and diagnostic purposes only, request bodies may be allowed using the non-compliant TraceEnable extended directive. The core (as an origin server) will restrict the request body to 64k (plus 8k for chunk headers ifTransfer-Encoding: chunked is used). The core will reflect the full headers and all chunk headers with the response body. As a proxy server, the request body is not restricted to 64k.

UseCanonicalName Directive

In many situations Apache must construct a self-referential URL -- that is, a URL that refers back to the same server. WithUseCanonicalName On Apache will use the hostname and port specified in the [ServerName](#servername) directive to construct the canonical name for the server. This name is used in all self-referential URLs, and for the values ofSERVER_NAME and SERVER_PORT in CGIs.

With UseCanonicalName Off Apache will form self-referential URLs using the hostname and port supplied by the client if any are supplied (otherwise it will use the canonical name, as defined above). These values are the same that are used to implement name based virtual hosts, and are available with the same clients. The CGI variablesSERVER_NAME and SERVER_PORT will be constructed from the client supplied values as well.

An example where this may be useful is on an intranet server where you have users connecting to the machine using short names such as www. You'll notice that if the users type a shortname and a URL which is a directory, such ashttp://www/splat, without the trailing slash, then Apache will redirect them tohttp://www.domain.com/splat/. If you have authentication enabled, this will cause the user to have to authenticate twice (once for www and once again for www.domain.com -- see the FAQ on this subject for more information). But ifUseCanonicalName is set Off, then Apache will redirect to http://www/splat/.

There is a third option, UseCanonicalName DNS, which is intended for use with mass IP-based virtual hosting to support ancient clients that do not provide aHost: header. With this option, Apache does a reverse DNS lookup on the server IP address that the client connected to in order to work out self-referential URLs.

Warning

If CGIs make assumptions about the values of SERVER_NAME, they may be broken by this option. The client is essentially free to give whatever value they want as a hostname. But if the CGI is only using SERVER_NAME to construct self-referential URLs, then it should be just fine.

See also

• [UseCanonicalPhysicalPort](#usecanonicalphysicalport)
• [ServerName](#servername)
• [Listen](../mod/mpm%5Fcommon.html#listen)

UseCanonicalPhysicalPort Directive

In many situations Apache must construct a self-referential URL -- that is, a URL that refers back to the same server. WithUseCanonicalPhysicalPort On, Apache will, when constructing the canonical port for the server to honor the [UseCanonicalName](#usecanonicalname) directive, provide the actual physical port number being used by this request as a potential port. With UseCanonicalPhysicalPort Off, Apache will not ever use the actual physical port number, instead relying on all configured information to construct a valid port number.

Note

The ordering of when the physical port is used is as follows:

UseCanonicalName On

• Port provided in Servername
• Physical port
• Default port

UseCanonicalName Off | DNS

• Parsed port from Host: header
• Physical port
• Port provided in Servername
• Default port

With UseCanonicalPhysicalPort Off, the physical ports are removed from the ordering.

See also

• [UseCanonicalName](#usecanonicalname)
• [ServerName](#servername)
• [Listen](../mod/mpm%5Fcommon.html#listen)

Directive

<VirtualHost> and</VirtualHost> are used to enclose a group of directives that will apply only to a particular virtual host. Any directive that is allowed in a virtual host context may be used. When the server receives a request for a document on a particular virtual host, it uses the configuration directives enclosed in the <VirtualHost> section. Addr can be:

• The IP address of the virtual host;
• A fully qualified domain name for the IP address of the virtual host (not recommended);
• The character *, which is used only in combination withNameVirtualHost * to match all IP addresses; or
• The string _default_, which is used only with IP virtual hosting to catch unmatched IP addresses.

Example

<VirtualHost 10.1.2.3:80> ServerAdmin webmaster@host.example.com DocumentRoot /www/docs/host.example.com ServerName host.example.com ErrorLog logs/host.example.com-error_log TransferLog logs/host.example.com-access_log </VirtualHost>

IPv6 addresses must be specified in square brackets because the optional port number could not be determined otherwise. An IPv6 example is shown below:

<VirtualHost [2001:db8::a00:20ff:fea7:ccea]:80> ServerAdmin webmaster@host.example.com DocumentRoot /www/docs/host.example.com ServerName host.example.com ErrorLog logs/host.example.com-error_log TransferLog logs/host.example.com-access_log </VirtualHost>

Each Virtual Host must correspond to a different IP address, different port number, or a different host name for the server, in the former case the server machine must be configured to accept IP packets for multiple addresses. (If the machine does not have multiple network interfaces, then this can be accomplished with the ifconfig alias command -- if your OS supports it).

Note

The use of <VirtualHost> doesnot affect what addresses Apache listens on. You may need to ensure that Apache is listening on the correct addresses using [Listen](../mod/mpm%5Fcommon.html#listen).

When using IP-based virtual hosting, the special name_default_ can be specified in which case this virtual host will match any IP address that is not explicitly listed in another virtual host. In the absence of any _default_ virtual host the "main" server config, consisting of all those definitions outside any VirtualHost section, is used when no IP-match occurs. (But note that any IP address that matches a [NameVirtualHost](#namevirtualhost) directive will use neither the "main" server config nor the _default_ virtual host. See the name-based virtual hosting documentation for further details.)

You can specify a :port to change the port that is matched. If unspecified then it defaults to the same port as the most recent [Listen](../mod/mpm%5Fcommon.html#listen) statement of the main server. You may also specify :* to match all ports on that address. (This is recommended when used with _default_.)

A [ServerName](#servername) should be specified inside each <VirtualHost> block. If it is absent, the[ServerName](#servername) from the "main" server configuration will be inherited.

Security

See the security tips document for details on why your security could be compromised if the directory where log files are stored is writable by anyone other than the user that starts the server.

See also

• Apache Virtual Host documentation
• Issues Regarding DNS and Apache
• Setting which addresses and ports Apache uses
• How , and sections work for an explanation of how these different sections are combined when a request is received