These configuration parameters control the core Apache features, and are always available.
AcceptFilter
on
AcceptFilter
controls a BSD specific filter
optimization. It is compiled in by default - and switched on by
default if your system supports it (setsocketopt() option
SO_ACCEPTFILTER). Currently only FreeBSD supports this.
See the filter section on performance hints for more information.
The compile time flag AP_ACCEPTFILTER_OFF
can
be used to change the default to 'off'. httpd -V
and httpd -L
will show compile time defaults and
whether or not SO_ACCEPTFILTER was defined during the
compile.
AcceptMutex
default
AcceptMutex
controls which accept() mutex
method Apache will use. Not all methods are available on all
platforms, since the suite of methods is determined at
compile-time. For a list of which methods are available for
your particular build, the httpd -L
command line
option will list them out.
The compile time flags -D
HAVE_METHOD_SERIALIZED_ACCEPT
can be used to add
different methods to your build, or one can edit the
include/ap_config.h
file for your particular
platform.
This directive has no effect on Microsoft Windows.
See the performance tuning guide for more information.
AccessConfig
conf/access.conf
The server will read this file for more directives after reading the ResourceConfig file. File-path is relative to the ServerRoot. This feature can be disabled using:
AccessConfig /dev/null
Or, on Win32 servers,
AccessConfig nul
Historically, this file only contained <Directory> sections; in fact it
can now contain any server directive allowed in the server
config context. However, since Apache version 1.3.4,
the default access.conf
file which ships with
Apache contains only comments, and all directives are placed
in the main server configuration file, httpd.conf
.
If AccessConfig
points to a directory, rather than a
file, Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.
Alternatively you can use a wildcard to limit the scope; i.e to only *.conf files.
Note that by default
So make sure that you don't have stray files in this directory by mistake, such as temporary files created by your editor, for example.
See also: Include and ResourceConfig.
AccessFileName
.htaccess
When returning a document to the client the server looks for the first existing access control file from this list of names in every directory of the path to the document, if access control 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 and Configuration Files
AddDefaultCharset Off
This directive specifies the name of the character set that
will be added to any response that does not have any parameter
on the content type in the HTTP headers. This will override any
character set specified in the body of the document via a
META
tag. A setting of AddDefaultCharset
Off
disables this functionality. AddDefaultCharset
On
enables Apache's internal default charset of
iso-8859-1
as required by the directive. You can
also specify an alternate charset to be used.
For example:
AddDefaultCharset utf-8
Note: This will not have any effect on the Content-Type and character set for default Apache-generated status pages (such as '404 Not Found' or '301 Moved Permanently') because those have an actual character set (that in which the hard-coded page content is written) and don't need to have a default applied.
The server can have modules compiled in which are not actively in use. This directive can be used to enable the use of those modules. The server comes with a pre-loaded list of active modules; this list can be cleared with the ClearModuleList directive.
For example:
AddModule mod_include.c
See also: ClearModuleList,
AllowOverride
All
When the server finds an .htaccess file (as specified by AccessFileName) it needs to know which directives declared in that file can override earlier access information.
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.
Example:
AllowOverride AuthConfig Indexes
See Also: AccessFileName and Configuration Files
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 and Require directives, and directives such as AuthUserFile and 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
This directive selects the type of user authentication for a
directory. Only Basic
and Digest
are
currently implemented.
It must be accompanied by AuthName and
Require directives, and directives such
as AuthUserFile and AuthGroupFile to
work.
See also: Authentication, Authorization, and Access Control
BindAddress
*
A Unix® http server can either listen for connections to every IP address of the server machine, or just one IP address of the server machine. If the argument to this directive is *, then the server will listen for connections on every IP address. Otherwise, the server can listen to only a specific IP-address or a fully-qualified Internet domain-name.
For example:
BindAddress 192.168.15.48
Only one BindAddress
directive can be used.
This directive is deprecated and will be eliminated in
Apache 2.0. Equivalent functionality and more control over the
address and ports Apache listens to is available using the
Listen
directive.
BindAddress
can be used as an alternative
method for supporting virtual hosts
using multiple independent servers, instead of using <VirtualHost>
sections.
See Also: DNS
Issues
See Also: Setting
which addresses and ports Apache uses
The BS2000Account
directive is available for
BS2000 hosts only. It must be used to define the account number
for the non-privileged apache server user (which was configured
using the User directive). This is required
by the BS2000 POSIX subsystem (to change the underlying BS2000
task environment by performing a sub-LOGON) to prevent CGI
scripts from accessing resources of the privileged account
which started the server, usually SYSROOT.
Only one BS2000Account
directive can be used.
See Also: Apache EBCDIC port
The server comes with a built-in list of active modules. This directive clears the list. It is assumed that the list will then be re-populated using the AddModule directive.
ContentDigest
off
This directive enables the generation of
Content-MD5
headers as defined in RFC1864
respectively RFC2068.
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, and not by any module. For example, SSI documents,
output from CGI scripts, and byte range responses do not have
this header.
This controls the directory to which Apache attempts to switch before dumping core. The default is in the ServerRoot directory, however since this should not be writable by the user the server runs as, core dumps won't normally get written. If you want a core dump for debugging, you can use this directive to place it in a different location.
For example:
CoreDumpDirectory /tmp
DefaultType
text/plain
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 must inform the client of the content-type of the
document, so in the event of an unknown type it uses the
DefaultType
. For example:
DefaultType image/gif
would be appropriate for a directory which contained many gif
images with filenames missing the .gif extension.
See also: AddType and TypesConfig.
<Directory> and </Directory> are used to enclose a group of directives which will apply only to the named directory and sub-directories of that directory. Any directive which is allowed in a directory context may be used. Directory-path is either the full path to a directory, or a wild-card string. In a wild-card string, `?' matches any single character, and `*' matches any sequences of characters. As of Apache 1.3, you may also use `[]' character ranges like in the shell. Also as of Apache 1.3 none of the wildcards match a `/' character, which more closely mimics the behavior of Unix shells. Example:
<Directory /usr/local/httpd/htdocs> Options Indexes FollowSymLinks </Directory>
Apache 1.2 and above: Extended 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 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
<Directory />
AllowOverride None
</Directory>
<Directory /home/*>
AllowOverride FileInfo
</Directory>
for access to the document /home/web/dir/doc.html
the steps are:
AllowOverride None
(disabling .htaccess
files).AllowOverride FileInfo
(for
directory /home/web
)./home/web/.htaccess
Regular expression directory sections are handled slightly differently by Apache 1.2 and 1.3. In Apache 1.2 they are interspersed with the normal directory sections and applied in the order they appear in the configuration file. They are applied only once, and apply when the shortest match possible occurs. In Apache 1.3 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 ~ abc$>
... directives here ...
</Directory>
Suppose that the filename being accessed is
/home/abc/public_html/abc/index.html
. The server
considers each of /
, /home
,
/home/abc
, /home/abc/public_html
, and
/home/abc/public_html/abc
in that order. In Apache
1.2, when /home/abc
is considered, the regular
expression will match and be applied. In Apache 1.3 the regular
expression isn't considered at all at that point in the tree.
It 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 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 typically occur in the access.conf file, but they may appear in any configuration file. <Directory> directives cannot nest, and cannot appear in a <Limit> or <LimitExcept> section.See also: How Directory, Location and Files sections work for an explanation of how these different sections are combined when a request is received
See also: DirectoryMatch
<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, the same as <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.
See Also: <Directory> for a description of
how regular expressions are mixed in with normal
<Directory>s.
See also: How
Directory, Location and Files sections work for an
explanation of how these different sections are combined when a
request is received
DocumentRoot
/usr/local/apache/htdocs
This directive sets the directory from which httpd will serve files. Unless matched by a directive like 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 to
http://www.my.host.com/index.html
refers to
/usr/web/index.html
.
There appears to be a bug in mod_dir which causes problems when the DocumentRoot has a trailing slash (i.e., "DocumentRoot /usr/web/") so please avoid that.
The EBCDICConvert directive maps the given filename extensions to the specified conversion setting (On or Off). File extensions may be specified with or without a leading dot.
If the optional format On=direction (or
Off=direction) is used, where
direction is one of In, Out or
InOut, then the directive only applies to the
specified transfer direction (In: uploaded content
in a PUT or POST request, Out: returned content in
a GET or POST request, and InOut: conversion in
both directions).
Otherwise, InOut (conversion in both directions)
is implied.
Conversion configuration based on file extension is tested prior to configuration based on MIME type, to allow for generic MIME based rules to be overridden by a more specific file extension (several file extensions may exist for the same MIME type).
Example:
With a configuration like the following, the normal
*.html files contain HTML text in EBCDIC encoding,
while *.ahtml files contain HTML text in ASCII
encoding:
# *.html and *.ahtml contain HTML text: AddType text/html .html .ahtml # *.ahtml is not converted (contains ASCII text already): EBCDICConvert Off .ahtml # All other text/html files presumably contain EBCDIC text: EBCDICConvertByType On text/html
See also: EBCDICConvertByType and Overview of the EBCDIC Conversion Functions
The EBCDICConvertByType directive maps the given MIME type (optionally containing wildcards) to the specified conversion setting (On or Off).
If the optional format On=direction (or
Off=direction) is used, where
direction is one of In, Out or
InOut, then the directive only applies to the
specified transfer direction (In: uploaded content
in a PUT or POST request, Out: returned content in
a GET or POST request, and InOut: conversion in
both directions).
Otherwise, InOut (conversion in both directions)
is implied.
Example:
A useful standard configuration should at least contain the
following defaults:
# All text documents are stored as EBCDIC files: EBCDICConvertByType On text/* message/* multipart/* EBCDICConvertByType On application/x-www-form-urlencoded \ model/vrml application/postscript # All other files are assumed to be binary: EBCDICConvertByType Off */*If you serve ASCII documents only, for example from an NFS mounted unix server, use:
# All documents are ASCII already: EBCDICConvertByType Off */*
See also: EBCDICConvert and Overview of the EBCDIC Conversion Functions
EBCDICKludge
Off
The EBCDICKludge is provided for the backward compatible behavior with apache versions 1.3.0 through 1.3.18. In these versions, all files with MIME types starting with "text/", "message/" or "multipart/" or with type "application/x-www-form-urlencoded" would be converted by default, all other documents were returned unconverted. Only if a MIME type "text/x-ascii-subtype" was configured for a certain document, the document was assumed to be in ASCII format already, and was not converted again. Instead, the "x-ascii-" was removed from the type, resulting in the MIME type "text/subtype" being returned for the document.
If the EBCDICKludge directive is set to On, and
if none of the file extensions configured with the EBCDICConvert directive matches in
the current context, then the server tests for a MIME type of
the format
type/x-ascii-subtype. If the
document has such a type, then the
"x-ascii-" substring is removed and the
conversion set to Off. This allows for overriding
the implicit assumption that all text files are stored in
EBCDIC format, for example when serving documents from an NFS
mounted directory with ASCII documents.
By using the EBCDICKludge, there is no way to force one of the
other MIME types (e.g., model/vrml) to be treated as
an EBCDIC text file. Use of the EBCDICConvertByType directive
mentioned above is the preferred way to configure such a
conversion. (Before Apache version 1.3.19, there was no way at
all to force these binary documents to be treated as EBCDIC
text files.)
See also: EBCDICConvert, EBCDICConvertByType and Overview of the EBCDIC Conversion Functions
In the event of a problem or error, Apache can be configured to do one of four things,
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 message or
URL.
Messages in this context begin with a single
double-quote character ("
), which does not form
part of the message itself. Apache will sometimes offer
additional information regarding the problem/error.
URLs can begin with a slash (/) for local URLs, or be a full URL which the client can resolve. 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
Note that when you specify an ErrorDocument
that points to a remote URL (ie. anything with a method such as
"http" 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 an
"ErrorDocument 401" directive then it must refer to a local
document.
See Also: documentation of customizable responses. See the HTTP specification for a complete list of the status codes and their meanings.
ErrorLog
logs/error_log
(Unix)ErrorLog
logs/error.log
(Windows and OS/2)The error log directive sets the name of the file to which the server will log any errors it encounters. If the file-path does not begin with a slash (/) then it is assumed to be relative to the ServerRoot. If the file-path begins with a pipe (|) then it is assumed to be a command to spawn to handle the error log.
Examples
ErrorLog logs/vhost1.error
ErrorLog |/usr/local/bin/errorlog.pl
Apache 1.3 and above: 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 where
facility can be one of the names usually documented in
syslog(1).
For example:
ErrorLog syslog
SECURITY: See the security tips document for details on why your security could be compromised if the directory where logfiles are stored is writable by anyone other than the user that starts the server.
See also: LogLevel and Apache Log Files
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 file. (The ETag value is used in cache management to save network bandwidth.) In Apache 1.3.22 and earlier, the ETag value was always formed from the file's inode, size, and last-modified time (mtime). The FileETag directive allows you to choose which of these -- if any -- should be used. The recognised keywords are:
FileETag INode MTime Size
')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 includes
'FileETag 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 to
'FileETag MTime Size
'.
The <Files> directive provides for access control by
filename. It is comparable to the <Directory> directive and <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> sections and .htaccess
files are
read, but before <Location> sections. Note that
<Files> can be nested inside <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. Extended 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. In Apache 1.3 and later, <FilesMatch> is preferred, however.
Note that unlike <Directory>
and <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.
For example, to password protect a single file within a
particular directory, you might add the following to your
.htaccess
file:
<Files admin.cgi> Require group admin </Files>
Remember that directives apply to subdirectories as well, so this
will also protect files called admin.cgi
in
subdirectories, unless specifically overridden.
(See Require for details on using the
Require
directive)
See also: How Directory, Location and Files sections work for an explanation of how these different sections are combined when a request is received
The <FilesMatch> directive provides for access control by filename, just as the <Files> directive does. However, it accepts a regular expression. For example:
<FilesMatch "\.(gif|jpe?g|png)$">
would match most common Internet graphics formats.
See also: How Directory, Location and Files sections work for an explanation of how these different sections are combined when a request is receivedGroup
#-1
The Group directive sets the group under which the server will answer requests. In order to use this directive, the stand-alone server must be run initially as root. Unix-group is one of:
nobody
,
but this is not always possible or desirable.
Note: if you start the server as a non-root user, it will fail to change to the specified group, and will instead continue to run as the group of the original user.
Special note: Use of this directive in <VirtualHost> requires a properly configured suEXEC wrapper. When used inside a <VirtualHost> in this manner, only the group that CGIs are run as is affected. Non-CGI requests are still processed as the group specified in the main Group directive.
SECURITY: See User for a discussion of the security considerations.
HostnameLookups
off
double
available only in Apache 1.3 and
above.on
prior to Apache 1.3.
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. 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 called
PARANOID
.)
Regardless of the setting, when mod_access 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 only
HostnameLookups 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 for this directive was previously
on
in versions of Apache prior to 1.3. It was
changed to 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 directive
off
, since DNS lookups can take considerable
amounts of time. The utility logresolve, provided in
the /support directory, can be used to look up host
names from logged IP addresses offline.
IdentityCheck
off
This directive enables RFC1413-compliant logging of the remote user name for each connection, where the client machine runs identd or something similar. This information is logged in the access log.
The information should not be trusted in any way except for rudimentary usage tracking.
Note that this can cause serious latency problems accessing your server since every request requires one of these lookups to be performed. When firewalls are involved each lookup might possibly fail and add 30 seconds of latency to each hit. So in general this is not very useful on public servers accessible from the Internet.
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-nameIn the former case, the directives between the start and end markers are only processed if the parameter named parameter-name is defined. The second format reverses the test, and only processes the directives if parameter-name is not defined.
The parameter-name argument is a define as given on
the httpd
command line via
-D
parameter-, 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 ... # httpd.conf <IfDefine ReverseProxy> LoadModule rewrite_module libexec/mod_rewrite.so LoadModule proxy_module libexec/libproxy.so </IfDefine>
The <IfModule test>...</IfModule> section is used to mark directives that are conditional. 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:
In the former case, the directives between the start and end markers are only processed if the module named module name is included in Apache -- either compiled in or dynamically loaded using LoadModule. The second format reverses the test, and only processes the directives if module name is not included.
The module name argument is the file name of the
module, at the time it was compiled.
For example, mod_rewrite.c
.
<IfModule> sections are nest-able, which can be used to implement simple multiple-module tests.
This directive allows inclusion of other configuration files from within the server configuration files.
The file path specified may be a fully qualified path (i.e.
starting with a slash), or may be relative to the
ServerRoot
directory.
New in Apache 1.3.13 is the feature that if
Include
points to a directory, rather than a file,
Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.
By using a wildcard this can be further limited to, say, just the '*.conf' files.
Examples:
Include /usr/local/apache/conf/ssl.conf
Include /usr/local/apache/conf/vhosts/
Or, providing paths relative to your ServerRoot
directory:
Include conf/ssl.conf
Include conf/vhosts/
Make sure that an included directory does not contain any stray
files, such as editor temporary files, for example, as Apache will
attempt to read them in and use the contents as configuration
directives, which may cause the server to fail on start up.
Running apachectl configtest
will give you a list of
the files that are being processed during the configuration
check:
root@host# apachectl configtest Processing config directory: /usr/local/apache/conf/vhosts Processing config file: /usr/local/apache/conf/vhosts/vhost1 Processing config file: /usr/local/apache/conf/vhosts/vhost2 Syntax OK
This will help in verifying that you are getting only the files that you intended as part of your configuration.
See also: apachectl
KeepAlive
5
KeepAlive
On
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 in Apache 1.2 and
later, set KeepAlive 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.
Apache 1.1 only: Set max-requests
to the maximum number of requests you want Apache to entertain
per connection. A limit is imposed to prevent a client from
hogging your server resources. Set this to 0
to
disable support. In Apache 1.2 and 1.3, this is controlled
through the MaxKeepAliveRequests directive instead.
See also MaxKeepAliveRequests.
KeepAliveTimeout
15
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
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.
Access controls are normally effective for
all 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, and DELETE, 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, TRACE, 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.
<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> section and can be used to control both standard and nonstandard/unrecognized methods. See the documentation for <Limit> for more details.
For example:
<LimitExcept POST GET> Require valid-user </LimitExcept>
LimitRequestBody
0
This directive specifies the number of bytes from 0
(meaning unlimited) to 2147483647 (2GB) that are allowed in a
request body. The default value is defined by the compile-time
constant DEFAULT_LIMIT_REQUEST_BODY
(0 as
distributed).
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 passing form information to the server. 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 wich to limit the size of the uploaded file to 100K, you might use the following directive:
LimitRequestBody 102400
LimitRequestFields 100
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
LimitRequestFieldsize 8190
This directive specifies the number of bytes from 0
to the value of the compile-time constant
DEFAULT_LIMIT_REQUEST_FIELDSIZE
(8190 as
distributed) that will be allowed in an HTTP request
header.
The LimitRequestFieldsize directive allows the server administrator to reduce the limit on the allowed size of an HTTP request header field below the normal input buffer size compiled with the server. 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.
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 16380
Under normal conditions, the value should not be changed from the default.
LimitRequestLine
8190
This directive sets the number of bytes from 0 to
the value of the compile-time constant
DEFAULT_LIMIT_REQUEST_LINE
(8190 as distributed)
that will be allowed on the HTTP request-line.
The LimitRequestLine directive allows the server administrator to reduce the limit on the allowed size of a client's HTTP request-line below the normal input buffer size compiled with the server. Since the request-line consists of the HTTP method, URI, and protocol version, the LimitRequestLine 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 16380
Under normal conditions, the value should not be changed from the default.
The Listen directive instructs Apache to listen to more than
one IP address or port; by default it responds to requests on
all IP interfaces, but only on the port given by the Port
directive.
Note that you may still require a Port directive so that URLs that Apache generates that point to your server still work.
Multiple Listen directives may be used to specify a number of addresses and ports to listen to. The server will respond to requests from any of the listed addresses and ports.
For example, to make the server accept connections on both port 80 and port 8000, use:
Listen 80 Listen 8000To make the server accept connections on two specified interfaces and port numbers, use
Listen 192.170.2.1:80 Listen 192.170.2.5:8000
See Also: DNS
Issues
See Also: Setting
which addresses and ports Apache uses
See Also: Known
Bugs
ListenBacklog
511
The maximum length of the queue of pending connections.
Generally no tuning is needed or desired, however on some
systems it is desirable to increase this when under a TCP SYN
flood attack. See the backlog parameter to the
listen(2)
system call.
This will often be limited to a smaller number by the operating system. This varies from OS to OS. Also note that many OSes do not use exactly what is specified as the backlog, but use a number based on (but normally larger than) what is set.
The <Location> directive provides for access control
by URL. It is similar to the <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> sections and .htaccess
files are
read, and after the <Files> sections.
Note that URLs do not have to line up with the filesystem at all, it should be emphasized that <Location> operates completely outside the filesystem.
For all origin (non-proxy) requests, the URL to be matched
is of the form /path/
, and you should not include
any http://servername
prefix. For proxy requests,
the URL to be matched is of the form
scheme://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.
Apache 1.2 and above: Extended 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". In Apache 1.3 and above, a new directive <LocationMatch> exists which
behaves identical to the regex version of
<Location>
.
The Location
functionality is especially useful
when combined with the SetHandler
directive. For example, to enable status requests, but allow
them only from browsers at foo.com, you might use:
<Location /status> SetHandler server-status Order Deny,Allow Deny from all Allow from .foo.com </Location>
Apache 1.3 and above 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>
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 Directory, Location and Files sections work for an explanation of how these different sections are combined when a request is received
The <LocationMatch> directive provides for access control by URL, in an identical manner to <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 Directory, Location and Files sections work for an explanation of how these different sections are combined when a request is receivedLockFile
logs/accept.lock
The LockFile directive sets the path to the lockfile used
when Apache is compiled with either USE_FCNTL_SERIALIZED_ACCEPT
or USE_FLOCK_SERIALIZED_ACCEPT. This directive should normally
be left at its default value. The main reason for changing it
is if the logs
directory is NFS mounted, since
the lockfile must be stored on a local disk.
The PID of the main server process is automatically appended to
the filename.
SECURITY: It is best to avoid putting this
file in a world writable directory such as
/var/tmp
because someone could create a denial of
service attack and prevent the server from starting by creating
a lockfile with the same name as the one the server will try to
create.
LogLevel
warn
LogLevel adjusts the verbosity of the messages recorded in the error logs (see ErrorLog directive). The following levels are available, in order of decreasing significance:
Level | Description | Example |
---|---|---|
emerg |
Emergencies - system is unusable. | "Child cannot open lock file. Exiting" |
alert |
Action must be taken immediately. | "getpwuid: couldn't determine user name from uid" |
crit |
Critical Conditions. | "socket: Failed to get a socket, exiting child" |
error |
Error conditions. | "Premature end of script headers" |
warn |
Warning conditions. | "child process 1234 did not exit, sending another SIGHUP" |
notice |
Normal but significant condition. | "httpd: caught SIGBUS, attempting to dump core in ..." |
info |
Informational. | "Server seems busy, (you may need to increase StartServers, or Min/MaxSpareServers)..." |
debug |
Debug-level messages | "Opening config file ..." |
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
and
warn
will also be posted.
Using a level of at least crit
is
recommended.
For example:
LogLevel notice
MaxClients
256
The MaxClients directive sets the limit on the number of simultaneous requests that can be supported; not more than this number of child server processes will be created. To configure more than 256 clients, you must edit the HARD_SERVER_LIMIT entry in httpd.h and recompile.
Any connection attempts over the MaxClients limit will normally be queued, up to a number based on the ListenBacklog directive. Once a child process is freed at the end of a different request, the connection will then be serviced.
MaxKeepAliveRequests 100
The MaxKeepAliveRequests directive limits the number of
requests allowed per connection when 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. In Apache 1.1, this is controlled through
an option to the KeepAlive directive.
For example
MaxKeepAliveRequests 500
MaxRequestsPerChild 0
The MaxRequestsPerChild directive sets the limit on the number of requests that an individual child server process will handle. After MaxRequestsPerChild requests, the child process will die. If MaxRequestsPerChild is 0, then the process will never expire.
Setting MaxRequestsPerChild to a non-zero limit has two beneficial effects:
However, on Win32, It is recommended that this be set to 0. If it is set to a non-zero value, when the request count is reached, the child process exits, and is respawned, at which time it re-reads the configuration files. This can lead to unexpected behavior if you have modified a configuration file, but are not expecting the changes to be applied yet. See also ThreadsPerChild.
NOTE: For KeepAlive requests, only the first request is counted towards this limit. In effect, it changes the behavior to limit the number of connections per child.
MaxSpareServers
10
The MaxSpareServers directive sets the desired maximum number of idle child server processes. An idle process is one which is not handling a request. If there are more than MaxSpareServers idle, then the parent process will kill off the excess processes.
Tuning of this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always a bad idea.
Note that this is the maximum number of spare servers, not the maximum total number of client requests that can be handled at one time. If you wish to limit that number, see the MaxClients directive.
This directive has no effect when used with the Apache Web server on a Microsoft Windows platform.
See also MinSpareServers, StartServers, and MaxClients.
MinSpareServers
5
The MinSpareServers directive sets the desired minimum number of idle child server processes. An idle process is one which is not handling a request. If there are fewer than MinSpareServers idle, then the parent process creates new children at a maximum rate of 1 per second.
Tuning of this parameter should only be necessary on very busy sites. Setting this parameter to a large number is almost always a bad idea.
Note that setting this directive to some value m ensures
that you will always have at least n + m httpd
processes running when you have n active client requests.
This directive has no effect on Microsoft Windows.
See also MaxSpareServers, StartServers, and MaxClients.
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 or wildcard, e.g.
NameVirtualHost 111.22.33.44
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: the "main server" and any _default_ servers will never be served for a request to a NameVirtualHost 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
In Apache 1.3.13 and greater you can specify a *
for the addr. This creates a wildcard NameVirtualHost
which will match connections to any address that isn't
configured with a more specific NameVirtualHost directive or <VirtualHost> section. This is
useful if you want only name-based virtual hosts and you don't
want to hard-code the server's IP address into the
configuration file.
See also: Apache Virtual Host documentation
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:
<Directory>
sections.Options
could apply to a
directory, then the most specific one is taken complete; the
options are not merged. However if all the options on
the Options
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.
For example, without any + and - symbols:
<Directory /web/docs>
Options Indexes FollowSymLinks
</Directory>
<Directory /web/docs/spec>
Options Includes
</Directory>
then only Includes
will be set for the
/web/docs/spec directory. However if the second
Options
directive uses the + and - symbols:
<Directory /web/docs>
Options Indexes FollowSymLinks
</Directory>
<Directory /web/docs/spec>
Options +Includes -Indexes
</Directory>
then the options FollowSymLinks
and
Includes
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 is
All
.
PidFile
logs/httpd.pid
The PidFile directive sets the file to which the server records the process id of the daemon. If the filename does not begin with a slash (/) then it is assumed to be relative to the ServerRoot. The PidFile is only used in standalone mode.
It is often useful to be able to send the server a signal, so that it closes and then reopens its ErrorLog and TransferLog, and re-reads its configuration files. This is done by sending a SIGHUP (kill -1) signal to the process id listed in the PidFile.
The PidFile is subject to the same warnings about log file placement and security.
Port
80
Number is a number from 0 to 65535; some port
numbers (especially below 1024) are reserved for particular
protocols. See /etc/services
for a list of some
defined ports; the standard port for the http protocol is
80.
The Port directive has two behaviors, the first of which is necessary for NCSA backwards compatibility (and which is confusing in the context of Apache).
:number
then Port has no effect on what address
the server listens at.SERVER_PORT
environment variable (for CGI and
SSI), and is used when the
server must generate a URL that refers to itself (for example
when creating an external redirect to itself). This behavior
is modified by UseCanonicalName.Port 80 is one of Unix's special ports. All ports numbered below 1024 are reserved for system use, i.e., regular (non-root) users cannot make use of them; instead they can only use higher port numbers. To use port 80, you must start the server from the root account. After binding to the port and before accepting requests, Apache will change to a low privileged user as set by the User directive.
If you cannot use port 80, choose any other unused port. Non-root users will have to choose a port number higher than 1023, such as 8000.
SECURITY: if you do start the server as root, be sure not to set User to root. If you run the server as root whilst handling connections, your site may be open to a major security attack.
ProtocolReqCheck
on
This directive enables strict checking of the Protocol field
in the Request line. Versions of Apache prior to 1.3.26 would
silently accept bogus Protocols (such as HTTP-1.1
)
and assume HTTP/1.0
. Instead, now the Protocol field
must be valid. If the pre-1.3.26 behavior is desired or required,
it can be enabled via setting ProtocolReqCheck off
.
This directive selects which authenticated users can access a directory. The allowed syntaxes are:
Only the named users can access the directory.
Only users in the named groups can access the directory.
All valid users can access the directory.
Require must be accompanied by AuthName and AuthType directives, and directives such as AuthUserFile and AuthGroupFile (to define users and groups) in order to work correctly. Example:
AuthType Basic
AuthName "Restricted Directory"
AuthUserFile /web/users
AuthGroupFile /web/groups
Require group admin
Access controls which are applied in this way are effective for
all 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> section
See also Satisfy and mod_access.
ResourceConfig
conf/srm.conf
The server will read this file for more directives after reading the httpd.conf file. File-path is relative to the ServerRoot. This feature can be disabled using:
ResourceConfig /dev/null
Or, on Win32 servers,
ResourceConfig nul
Historically, this file contained most directives except for
server configuration directives and <Directory> sections; in fact it
can now contain any server directive allowed in the server
config context. However, since Apache version 1.3.4, the
default srm.conf
file which ships with Apache contains
only comments, and all directives are placed in the main server
configuration file, httpd.conf
.
If ResourceConfig
points to a directory, rather than
a file, Apache will read all files in that directory, and any
subdirectory, and parse those as configuration files.
Alternatively you can use a wildcard to limit the scope; i.e to only *.conf files.
Note that by default
So make sure that you don't have stray files in this directory by mistake, such as temporary files created by your editor, for example.
See also AccessConfig.
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 off from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked off from the Apache parent such as piped logs.
CPU resource limits are expressed in seconds per process.
See also RLimitMEM or RLimitNPROC.
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 off from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked off from the Apache parent such as piped logs.
Memory resource limits are expressed in bytes per process.
See also RLimitCPU or RLimitNPROC.
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 off from Apache children servicing requests, not the Apache children themselves. This includes CGI scripts and SSI exec commands, but not any processes forked off 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 userids other than the web server userid, 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 the error_log.
See also RLimitMEM or RLimitCPU.
Access policy if both Allow
and
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.
ScoreBoardFile
logs/apache_status
The ScoreBoardFile directive is required on some architectures to place a file that the server will use to communicate between its children and the parent. The easiest way to find out if your architecture requires a scoreboard file is to run Apache and see if it creates the file named by the directive. If your architecture requires it then you must ensure that this file is not used at the same time by more than one invocation of Apache.
If you have to use a ScoreBoardFile then you may see improved speed by placing it on a RAM disk. But be careful that you heed the same warnings about log file placement and security.
Apache 1.2 and above:
Linux 1.x users might be able to add -DHAVE_SHMGET
-DUSE_SHMGET_SCOREBOARD
to the EXTRA_CFLAGS
in your Configuration
. This might work with some
1.x installations, but won't work with all of them. (Prior to
1.3b4, HAVE_SHMGET
would have sufficed.)
SVR4 users should consider adding -DHAVE_SHMGET
-DUSE_SHMGET_SCOREBOARD
to the EXTRA_CFLAGS
in your Configuration
. This is believed to work,
but we were unable to test it in time for 1.2 release. (Prior
to 1.3b4, HAVE_SHMGET
would have sufficed.)
See Also: Stopping and Restarting Apache
ScriptInterpreterSource script
This directive is used to control how Apache 1.3.5 and later finds the interpreter used to run CGI scripts. The default technique is to use the interpreter pointed to by the #! line in the script. Setting ScriptInterpreterSource registry will cause the Windows Registry to be searched using the script file extension (e.g., .pl) as a search key.
The server will set the TCP buffer size to the number of bytes specified. Very useful to increase past standard OS defaults on high speed high latency (i.e., 100ms or so, such as transcontinental fast pipes)
The ServerAdmin sets the e-mail address that the server includes in any error messages it returns to the client.
It may be worth setting up a dedicated address for this, e.g.
ServerAdmin www-admin@foo.bar.com
as users do not always mention that they are talking about the
server!
The ServerAlias directive sets the alternate names for a host, for use with name-based virtual hosts.
Example:
<VirtualHost *> ServerName server.domain.com ServerAlias server server2.domain.com server2 ... </VirtualHost>
See also: Apache Virtual Host documentation
The ServerName directive sets the hostname of the server; this is used when creating redirection URLs. If it is not specified, then the server attempts to deduce it from its own IP address; however this may not work reliably, or may not return the preferred hostname. For example:
ServerName www.example.com
would be used if the canonical (main) name of the actual
machine were simple.example.com
.
If you are using name-based virtual hosts,
the ServerName
inside a <VirtualHost>
section specifies what hostname must appear in the request's
Host:
header to match this virtual host.
See Also:
DNS Issues
Apache virtual host
documentation
UseCanonicalName
NameVirtualHost
ServerAlias
The ServerPath directive sets the legacy URL pathname for a host, for use with name-based virtual hosts.
See also: Apache Virtual Host documentation
ServerRoot
/usr/local/apache
The ServerRoot directive sets the directory in which the
server lives. Typically it will contain the subdirectories
conf/
and logs/
. Relative paths for
other configuration files are taken as relative to this
directory.
See also the -d
option to httpd.
See also the security tips for information on how to properly set permissions on the ServerRoot.
ServerSignature
Off
The ServerSignature directive allows the configuration of a
trailing footer line under server-generated documents (error
messages, mod_proxy ftp directory listings, mod_info 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 error 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 of the serving virtual host,
and the EMail setting additionally creates a
"mailto:" reference to the ServerAdmin of the referenced
document.
ServerTokens
Full
ProductOnly
keyword is only available in versions
later than 1.3.12
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]
ServerTokens Min[imal]
ServerTokens OS
ServerTokens Full
(or not specified)This setting applies to the entire server, and cannot be enabled or disabled on a virtualhost-by-virtualhost basis.
ServerType
standalone
The ServerType directive sets how the server is executed by the system. Type is one of
/etc/inetd.conf
/etc/rc.local
or
/etc/rc3.d/...
.)Standalone is the most common setting for ServerType since it is far more efficient. The server is started once, and services all subsequent connections. If you intend running Apache to serve a busy site, standalone will probably be your only option.
ShmemUIDisUser
off
The ShmemUIDisUser directive controls whether Apache will change
the uid
and gid
ownership of System V shared memory
based scoreboards to the server settings of User and
Group. Releases of Apache up to 1.3.26 would do
this by default. Since the child processes are already attached to the
shared memory segment, this is not required for normal usage of Apache and
so to prevent possible abuse, Apache will no longer do that. The old
behavior may be required for special cases, however, which can be implemented
by setting this directive to on
.
This directive has no effect on non-System V based scoreboards, such as
mmap
.
StartServers
5
The StartServers directive sets the number of child server processes created on startup. As the number of processes is dynamically controlled depending on the load, there is usually little reason to adjust this parameter.
When running under Microsoft Windows, this directive has no effect. There is always one child which handles all requests. Within the child requests are handled by separate threads. The ThreadsPerChild directive controls the maximum number of child threads handling requests, which will have a similar effect to the setting of StartServers on Unix.
See also MinSpareServers and MaxSpareServers.
ThreadsPerChild
50
This directive tells the server how many threads it should use. This is the maximum number of connections the server can handle at once; be sure and set this number high enough for your site if you get a lot of hits.
This directive has no effect on Unix systems. Unix users should look at StartServers and MaxRequestsPerChild.
ThreadStackSize
65536
This directive tells the server what stack size to use for each of the running threads. If you ever get a stack overflow you will need to bump this number to a higher setting.
This directive has no effect on other systems.
TimeOut
300
The TimeOut directive currently defines the amount of time Apache will wait for three things:
UseCanonicalName
on
In many situations Apache has to construct a
self-referential URL. That is, a URL which refers back
to the same server. With UseCanonicalName on
(and
in all versions prior to 1.3) Apache will use the ServerName and Port
directives to construct the canonical name for the server. This
name is used in all self-referential URLs, and for the values
of SERVER_NAME
and SERVER_PORT
in
CGIs.
For example, if ServerName is set to
www.example.com
and Port is set to
9090
, then the canonical name of the server is
www.example.com:9090
. In the event that
Port
has its default value of 80
, the
:80
is ommitted from the canonical name.
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 variables
SERVER_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 as
http://www/splat
, without the trailing
slash then Apache will redirect them to
http://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 if UseCanonicalName
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 a
Host:
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: ServerName, Port
User
#-1
The User directive sets the userid as which the server will answer requests. In order to use this directive, the standalone server must be run initially as root. Unix-userid is one of:
nobody
, but this is not always possible or
desirable. For example mod_proxy's cache, when enabled, must be
accessible to this user (see the CacheRoot
directive).
Notes: If you start the server as a non-root user, it will fail to change to the lesser privileged user, and will instead continue to run as that original user. If you do start the server as root, then it is normal for the parent process to remain running as root.
Special note: Use of this directive in <VirtualHost> requires a properly configured suEXEC wrapper. When used inside a <VirtualHost> in this manner, only the user that CGIs are run as is affected. Non-CGI requests are still processed with the user specified in the main User directive.
SECURITY: Don't set User (or Group) to
root
unless you know exactly what you are doing,
and what the dangers are.
<VirtualHost> and </VirtualHost> are used to enclose a group of directives which will apply only to a particular virtual host. Any directive which 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
<VirtualHost 10.1.2.3>
ServerAdmin webmaster@host.foo.com
DocumentRoot /www/docs/host.foo.com
ServerName host.foo.com
ErrorLog logs/host.foo.com-error_log
TransferLog logs/host.foo.com-access_log
</VirtualHost>
Each VirtualHost 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), or with kernel patches like VIF (for SunOS(TM) 4.1.x)).
You can specify more than one IP address. This is useful if a machine responds to the same name on two different interfaces. For example, if you have a VirtualHost that is available to hosts on an internal (intranet) as well as external (internet) network. Example:
<VirtualHost 192.168.1.2 204.255.176.199>
DocumentRoot /www/docs/host.foo.com
ServerName host.foo.com
ServerAlias host
</VirtualHost>
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 match occurs.
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 Port
statement
of the main server. You may also specify :*
to
match all ports on that address. (This is recommended when used
with _default_
.)
SECURITY: See the security tips document for details on why your security could be compromised if the directory where logfiles are stored is writable by anyone other than the user that starts the server.
NOTE: The use of <VirtualHost> does not affect what addresses Apache listens on. You may need to ensure that Apache is listening on the correct addresses using either BindAddress or Listen.
See also: Apache
Virtual Host documentation
See also: Warnings about DNS and
Apache
See also: Setting
which addresses and ports Apache uses
See also: How
Directory, Location and Files sections work for an
explanation of how these different sections are combined when a
request is received