The behaviour of these functions is affected by settings in php.ini.
Name | Default | Changeable | Changelog |
---|---|---|---|
session.save_path | "" | INI_ALL | |
session.name | "PHPSESSID" | INI_ALL | |
session.save_handler | "files" | INI_ALL | |
session.auto_start | "0" | INI_PERDIR | |
session.gc_probability | "1" | INI_ALL | |
session.gc_divisor | "100" | INI_ALL | |
session.gc_maxlifetime | "1440" | INI_ALL | |
session.serialize_handler | "php" | INI_ALL | |
session.cookie_lifetime | "0" | INI_ALL | |
session.cookie_path | "/" | INI_ALL | |
session.cookie_domain | "" | INI_ALL | |
session.cookie_secure | "0" | INI_ALL | Prior to PHP 7.2.0, the default was "" . |
session.cookie_httponly | "0" | INI_ALL | Prior to PHP 7.2.0, the default was "" . |
session.cookie_samesite | "" | INI_ALL | Available as of PHP 7.3.0. |
session.use_strict_mode | "0" | INI_ALL | |
session.use_cookies | "1" | INI_ALL | |
session.use_only_cookies | "1" | INI_ALL | |
session.referer_check | "" | INI_ALL | |
session.cache_limiter | "nocache" | INI_ALL | |
session.cache_expire | "180" | INI_ALL | |
session.use_trans_sid | "0" | INI_ALL | |
session.trans_sid_tags | "a=href,area=href,frame=src,form=" | INI_ALL | Available as of PHP 7.1.0. |
session.trans_sid_hosts | $_SERVER['HTTP_HOST'] | INI_ALL | Available as of PHP 7.1.0. |
session.sid_length | "32" | INI_ALL | Available as of PHP 7.1.0. |
session.sid_bits_per_character | "4" | INI_ALL | Available as of PHP 7.1.0. |
session.upload_progress.enabled | "1" | INI_PERDIR | |
session.upload_progress.cleanup | "1" | INI_PERDIR | |
session.upload_progress.prefix | "upload_progress_" | INI_PERDIR | |
session.upload_progress.name | "PHP_SESSION_UPLOAD_PROGRESS" | INI_PERDIR | |
session.upload_progress.freq | "1%" | INI_PERDIR | |
session.upload_progress.min_freq | "1" | INI_PERDIR | |
session.lazy_write | "1" | INI_ALL | |
session.hash_function | "0" | INI_ALL | Removed as of PHP 7.1.0. |
session.hash_bits_per_character | "4" | INI_ALL | Removed as of PHP 7.1.0. |
session.entropy_file | "" | INI_ALL | Removed as of PHP 7.1.0. |
session.entropy_length | "0" | INI_ALL | Removed as of PHP 7.1.0 |
The session management system supports a number of configuration options which you can place in your php.ini file. We will give a short overview.
session.save_handler
stringsession.save_handler
defines the name of the handler which is used for storing and retrieving data associated with a session. Defaults to files
. Note that individual extensions may register their own save_handler
s; registered handlers can be obtained on a per-installation basis by referring to phpinfo(). See also session_set_save_handler(). session.save_path
stringsession.save_path
defines the argument which is passed to the save handler. If you choose the default files handler, this is the path where the files are created. See also session_save_path(). There is an optional N
argument to this directive that determines the number of directory levels your session files will be spread around in. For example, setting to '5;/tmp'
may end up creating a session file and location like /tmp/4/b/1/e/3/sess_4b1e384ad74619bd212e236e52a5a174If
. In order to use N
you must create all of these directories before use. A small shell script exists in ext/session to do this, it's called mod_files.sh, with a Windows version called mod_files.bat. Also note that if N
is used and greater than 0 then automatic garbage collection will not be performed, see a copy of php.ini for further information. Also, if you use N
, be sure to surround session.save_path
in "quotes" because the separator (;
) is also used for comments in php.ini.
The file storage module creates files using mode 600 by default. This default can be changed with the optional MODE
argument: N;MODE;/path
where MODE
is the octal representation of the mode. Setting MODE
does not affect the process umask.
If this is set to a world-readable directory, such as /tmp (the default), other users on the server may be able to hijack sessions by getting the list of files in that directory.
When using the optional directory level argument N
, as described above, note that using a value higher than 1 or 2 is inappropriate for most sites due to the large number of directories required: for example, a value of 3 implies that (2 ** session.sid_bits_per_character) ** 3
directories exist on the filesystem, which can result in a lot of wasted space and inodes.
Only use N
greater than 2 if you are absolutely certain that your site is large enough to require it.
session.name
stringsession.name
specifies the name of the session which is used as cookie name. It should only contain alphanumeric characters. Defaults to PHPSESSID
. See also session_name(). session.auto_start
boolsession.auto_start
specifies whether the session module starts a session automatically on request startup. Defaults to 0
(disabled). session.serialize_handler
stringsession.serialize_handler
defines the name of the handler which is used to serialize/deserialize data. PHP serialize format (name php_serialize
), PHP internal formats (name php
and php_binary
) and WDDX are supported (name wddx
). WDDX is only available, if PHP is compiled with WDDX support. php_serialize
uses plain serialize/unserialize function internally and does not have limitations that php
and php_binary
have. Older serialize handlers cannot store numeric index nor string index contains special characters (|
and !
) in $_SESSION. Use php_serialize
to avoid numeric index or special character errors at script shutdown. Defaults to php
. session.gc_probability
intsession.gc_probability
in conjunction with session.gc_divisor
is used to manage probability that the gc (garbage collection) routine is started. Defaults to 1
. See session.gc_divisor for details. session.gc_divisor
intsession.gc_divisor
coupled with session.gc_probability
defines the probability that the gc (garbage collection) process is started on every session initialization. The probability is calculated by using gc_probability/gc_divisor, e.g. 1/100 means there is a 1% chance that the GC process starts on each request. session.gc_divisor
defaults to 100
. session.gc_maxlifetime
intsession.gc_maxlifetime
specifies the number of seconds after which data will be seen as 'garbage' and potentially cleaned up. Garbage collection may occur during session start (depending on session.gc_probability and session.gc_divisor). Defaults to 1440
(24 minutes). Note: If different scripts have different values of
session.gc_maxlifetime
but share the same place for storing the session data then the script with the minimum value will be cleaning the data. In this case, use this directive together with session.save_path.
session.referer_check
stringsession.referer_check
contains the substring you want to check each HTTP Referer for. If the Referer was sent by the client and the substring was not found, the embedded session id will be marked as invalid. Defaults to the empty string. session.entropy_file
stringsession.entropy_file
gives a path to an external resource (file) which will be used as an additional entropy source in the session id creation process. Examples are /dev/random
or /dev/urandom
which are available on many Unix systems. This feature is supported on Windows. Setting session.entropy_length
to a non zero value will make PHP use the Windows Random API as entropy source. Note: Removed in PHP 7.1.0.
session.entropy_file
defaults to/dev/urandom
or/dev/arandom
if it is available.
session.entropy_length
intsession.entropy_length
specifies the number of bytes which will be read from the file specified above. Defaults to 32
. Removed in PHP 7.1.0. session.use_strict_mode
boolsession.use_strict_mode
specifies whether the module will use strict session id mode. If this mode is enabled, the module does not accept uninitialized session IDs. If an uninitialized session ID is sent from the browser, a new session ID is sent to the browser. Applications are protected from session fixation via session adoption with strict mode. Defaults to 0
(disabled). Note: Enabling
session.use_strict_mode
is mandatory for general session security. All sites are advised to enable this. See session_create_id() example code for more details.
If a custom session handler registered via session_set_save_handler() does not implement SessionUpdateTimestampHandlerInterface::validateId(), nor supplies the validate_sid
callback, respectively, strict session ID mode is effectively disabled, regardless of the value of this directive. Particularly note that SessionHandler does not implement SessionHandler::validateId().
session.use_cookies
specifies whether the module will use cookies to store the session id on the client side. Defaults to 1
(enabled). session.use_only_cookies
specifies whether the module will only use cookies to store the session id on the client side. Enabling this setting prevents attacks that involve passing session IDs in URLs. Defaults to 1
(enabled). session.cookie_lifetime
specifies the lifetime of the cookie in seconds which is sent to the browser. The value 0 means "until the browser is closed." Defaults to 0
. See also session_get_cookie_params() and session_set_cookie_params(). Note: The expiration timestamp is set relative to the server time, which is not necessarily the same as the time in the client's browser.
session.cookie_path
specifies path to set in the session cookie. Defaults to /
. See also session_get_cookie_params() and session_set_cookie_params(). session.cookie_domain
specifies the domain to set in the session cookie. Default is none at all meaning the host name of the server which generated the cookie according to cookies specification. See also session_get_cookie_params() and session_set_cookie_params(). session.cookie_secure
specifies whether cookies should only be sent over secure connections. With this option set to on
, sessions only work with HTTPS connections. If it is off
, then sessions work with both HTTP and HTTPS connections. Defaults to off
. See also session_get_cookie_params() and session_set_cookie_params(). Lax
and Strict
mean that the cookie will not be sent cross-domain for POST requests; Lax
will send the cookie for cross-domain GET requests, while Strict
will not. session.cache_limiter
stringsession.cache_limiter
specifies the cache control method used for session pages. It may be one of the following values: nocache
, private
, private_no_expire
, or public
. Defaults to nocache
. See also the session_cache_limiter() documentation for information about what these values mean. session.cache_expire
intsession.cache_expire
specifies time-to-live for cached session pages in minutes, this has no effect for nocache limiter. Defaults to 180
. See also session_cache_expire(). session.use_trans_sid
boolsession.use_trans_sid
whether transparent sid support is enabled or not. Defaults to 0
(disabled). Note: URL based session management has additional security risks compared to cookie based session management. Users may send a URL that contains an active session ID to their friends by email or users may save a URL that contains a session ID to their bookmarks and access your site with the same session ID always, for example. Since PHP 7.1.0, full URL path, e.g. https://php.net/, is handled by trans sid feature. Previous PHP handled relative URL path only. Rewrite target hosts are defined by session.trans_sid_hosts.
session.trans_sid_tags
specifies which HTML tags are rewritten to include session id when transparent sid support is enabled. Defaults to a=href,area=href,frame=src,input=src,form=
form
is special tag. <input hidden="session_id" name="session_name">
is added as form variable. Note: Before PHP 7.1.0, url_rewriter.tags was used for this purpose. Since PHP 7.1.0,
fieldset
is no longer considered as special tag.
session.trans_sid_hosts
stringsession.trans_sid_hosts
specifies which hosts are rewritten to include session id when transparent sid support is enabled. Defaults to $_SERVER['HTTP_HOST']
Multiple hosts can be specified by ",", no space is allowed between hosts. e.g. php.net,wiki.php.net,bugs.php.net
session.sid_length
intsession.sid_length
allows you to specify the length of session ID string. Session ID length can be between 22 to 256. The default is 32. If you need compatibility you may specify 32, 40, etc. Longer session ID is harder to guess. At least 32 chars are recommended. Compatibility Note: Use 32 instead of session.hash_function
=0 (MD5) and session.hash_bits_per_character
=4, session.hash_function
=1 (SHA1) and session.hash_bits_per_character
=6. Use 26 instead of session.hash_function
=0 (MD5) and session.hash_bits_per_character
=5. Use 22 instead of session.hash_function
=0 (MD5) and session.hash_bits_per_character
=6. You must configure INI values to have at least 128 bits in session ID. Do not forget to set an appropriate value for session.sid_bits_per_character
, otherwise you will have weaker session ID.
Note: This setting is introduced in PHP 7.1.0.
session.sid_bits_per_character
intsession.sid_bits_per_character
allows you to specify the number of bits in encoded session ID character. The possible values are '4' (0-9, a-f), '5' (0-9, a-v), and '6' (0-9, a-z, A-Z, "-", ","). The default is 4. The more bits results in stronger session ID. 5 is recommended value for most environments. Note: This setting is introduced in PHP 7.1.0.
session.hash_function
mixedsession.hash_function
allows you to specify the hash algorithm used to generate the session IDs. '0' means MD5 (128 bits) and '1' means SHA-1 (160 bits). It is also possible to specify any of the algorithms provided by the hash extension (if it is available), like sha512
or whirlpool
. A complete list of supported algorithms can be obtained with the hash_algos() function.
Note: Removed in PHP 7.1.0.
session.hash_bits_per_character
intsession.hash_bits_per_character
allows you to define how many bits are stored in each character when converting the binary hash data to something readable. The possible values are '4' (0-9, a-f), '5' (0-9, a-v), and '6' (0-9, a-z, A-Z, "-", ","). Note: Removed in PHP 7.1.0.
session.upload_progress.enabled
boolsession.upload_progress.cleanup
boolNote: It is highly recommended to keep this feature enabled.
session.upload_progress.prefix
string$_POST[ini_get("session.upload_progress.name")]
to provide a unique index. Defaults to "upload_progress_". session.upload_progress.name
string$_POST[ini_get("session.upload_progress.name")]
is not passed or available, upload progressing will not be recorded. Defaults to "PHP_SESSION_UPLOAD_PROGRESS". session.upload_progress.freq
mixedsession.upload_progress.min_freq
intsession.lazy_write
boolsession.lazy_write
, when set to 1, means that session data is only rewritten if it changes. Defaults to 1, enabled. Upload progress will not be registered unless session.upload_progress.enabled is enabled, and the $_POST[ini_get("session.upload_progress.name")] variable is set. See Session Upload Progress for more details on this functionality.