![[APACHE DOCUMENTATION]](../images/sub.gif)
AccessConfig conf/access.confThe server will read this file for more directives after reading the ResourceConfig file. Filename is relative to the ServerRoot. This feature can be disabled using:
AccessConfig /dev/nullAccessFileName .htaccessWhen returning a document to the client the server looks for an access control file with this name in every directory of the path to the document, if access control files are enabled for that directory. For example:
AccessFileName .acl
<Directory />
AllowOverride None
</Directory>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.
AllowOverride AllWhen 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.
Override can be set to None, in which case the server
will not read the file, All in which case the server will
allow all the directives, or one or more of the following:
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. It must be accompanied by AuthType and require directives, and directives such as AuthUserFile and AuthGroupFile to work.
This directive selects the type of user authentication for a directory.
Only Basic is currently implemented.
It must be accompanied by AuthName and
require directives, and directives such as
AuthUserFile and
AuthGroupFile to work.
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. Saddr can be
If the value is *, then the server will listen for connections on every IP address, otherwise it will only listen on the IP address specified.This option can be used as an alternative method for supporting virtual hosts instead of using <VirtualHost> sections.
See Also:
DNS Issues
See Also:
Setting which addresses and ports Apache uses
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.
DefaultType text/htmlThere 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<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 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. 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 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>/home/web/dir/doc.html the
steps are:
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> section.DocumentRoot
/usr/local/etc/httpd/htdocsThis 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/webhttp://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.
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 quote
("), 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 if you use an "ErrorDocument 401"
directive then it must refer to a local document. This results
from the nature of the HTTP basic authentication scheme.
See Also: documentation of customizable responses.
ErrorLog logs/error_logThe error log directive sets the name of the file to which the server will log any errors it encounters. If the filename does not begin with a slash (/) then it is assumed to be relative to the ServerRoot. Example:
ErrorLog /dev/nullSECURITY: 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.
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. Directives that
apply to the filename given should be listed
within. <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.
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.
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. When used in an .htaccess file, if the
filename does not begin with a / character,
the directory being applied will be prefixed automatically.
Group #-1The 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 on
This directive enables DNS lookups so that host names can be logged.
Having this directive set on also enables the use of names
in <Limit> blocks for access control.
Heavily loaded sites should set 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. Boolean is either
on or off.
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 <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 compiled in to Apache. The second format reverses the test, and only processes the directives if module name is not compiled in.
The module name argument is a module name as given as 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.
KeepAlive 5KeepAlive OnThis directive enables Keep-Alive support.
Apache 1.1: Set max-requests
to the maximum number of requests you want Apache to entertain per
request. A limit is imposed to prevent a client from hogging your
server resources. Set this to 0 to disable support.
Apache 1.2 and later: Set to "On" to enable persistent connections, "Off" to disable. See also the MaxKeepAliveRequests directive.
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.
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.
See Also:
DNS Issues
See Also:
Setting which addresses and ports Apache uses
See Also:
Known Bugs
<Limit> and </Limit> are used to enclose a group of access control directives which will then apply only to the specified access methods, where method is any valid HTTP method. Any directive except another <Limit> or <Directory> may be used; the majority will be unaffected by the <Limit>. Example:
<Limit GET POST>
require valid-user
</Limit>
The <Location> directive provides for access control by
URL. It is comparable to the <Directory> directive, and
should be matched with a </Location> directive. Directives that
apply to the URL given should be listed
within. <Location> sections are processed in the
order they appear in the configuration file, after the
<Directory> sections and .htaccess files are
read.
Note that, due to the way HTTP functions, URL prefix
should, save for proxy requests, be of the form /path/,
and should not include the http://servername. It doesn't
necessarily have to protect a directory (it can be an individual
file, or a number of files), and can include wild-cards. 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".
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>
LockFile 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
should be stored on a local disk if possible. The PID of the main
server process is automatically appended to the filename.
MaxClients 256The 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.
MaxKeepAliveRequests 100The 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.
MaxRequestsPerChild directive
Syntax: MaxRequestsPerChild number
Default: MaxRequestsPerChild 0
Context: server config
Status: core
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:
MaxSpareServers 10The 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.
See also MinSpareServers and StartServers.
MinSpareServers 5The 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.
See also MaxSpareServers and StartServers.
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>
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>
FollowSymLinks and Includes
are set for the /web/docs/spec directory.
PidFile logs/httpd.pidThe 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).
The primary behaviour of Port should be considered to be similar to that of the ServerName directive. The ServerName and Port together specify what you consider to be the canonical address of the server.
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.
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.
If require appears in a <Limit>
section, then it restricts access to the named methods, otherwise
it restricts access for all methods. Example:
AuthType Basic
AuthName somedomain
AuthUserFile /web/users
AuthGroupFile /web/groups
<Limit GET POST>
require group admin
</Limit>
ResourceConfig conf/srm.confThe server will read this file for more directives after reading the httpd.conf file. Filename is relative to the ServerRoot. This feature can be disabled using:
ResourceConfig /dev/nullSee also AccessConfig.
Unset uses operating system defaultsTakes 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.
CPU resource limits are expressed in seconds per process.
See also RLimitMEM or RLimitNPROC.
Unset uses operating system defaultsTakes 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.
Memory resource limits are expressed in bytes per process.
See also RLimitCPU or RLimitNPROC.
Unset uses operating system defaultsTakes 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.
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_statusThe 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 to
the EXTRA_CFLAGS in your Configuration. This
might work with some 1.x installations, but won't work with all of
them.
SVR4 users should consider adding -DHAVE_SHMGET 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.
See Also: Stopping and Restarting Apache
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.comThe ServerAlias directive sets the alternate names for a host, for use with Host-header based virtual hosts.
See Also: In-depth description of Virtual Host matching
The ServerName directive sets the hostname of the server; this is only 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.wibble.commonster.wibble.com.
See Also: DNS Issues
The ServerPath directive sets the legacy URL pathname for a host, for use with Host-header based virtual hosts.
See Also: In-depth description of Virtual Host matching
ServerRoot /usr/local/etc/httpd
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.
ServerType standaloneThe 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.
SECURITY: if you are paranoid about security, run in inetd mode. Security cannot be guaranteed in either, but whilst most people are happy to use standalone, inetd is probably least prone to attack.
StartServers 5The 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.
See also MinSpareServers and MaxSpareServers.
TimeOut 300The TimeOut directive currently defines the amount of time Apache will wait for three things:
User #-1The 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.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
Example:
<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 or a
different host name for the server, in the latter 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)).
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.
See also:
Warnings about DNS and Apache
See also:
Information on Virtual Hosts.
(multihome)
See also:
Non-IP address-based Virtual Hosts
See also:
In-depth description of Virtual Host matching
