The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog |
|---|---|---|---|
| session.save_path | "" | PHP_INI_ALL | |
| session.name | "PHPSESSID" | PHP_INI_ALL | |
| session.save_handler | "files" | PHP_INI_ALL | |
| session.auto_start | "0" | PHP_INI_PERDIR | |
| session.gc_probability | "1" | PHP_INI_ALL | |
| session.gc_divisor | "100" | PHP_INI_ALL | |
| session.gc_maxlifetime | "1440" | PHP_INI_ALL | |
| session.serialize_handler | "php" | PHP_INI_ALL | |
| session.cookie_lifetime | "0" | PHP_INI_ALL | |
| session.cookie_path | "/" | PHP_INI_ALL | |
| session.cookie_domain | "" | PHP_INI_ALL | |
| session.cookie_secure | "0" | PHP_INI_ALL | Prior to PHP 7.2.0, the default was "". |
| session.cookie_httponly | "0" | PHP_INI_ALL | Prior to PHP 7.2.0, the default was "". |
| session.cookie_samesite | "" | PHP_INI_ALL | Available as of PHP 7.3.0. |
| session.use_strict_mode | "0" | PHP_INI_ALL | |
| session.use_cookies | "1" | PHP_INI_ALL | |
| session.use_only_cookies | "1" | PHP_INI_ALL | |
| session.referer_check | "" | PHP_INI_ALL | |
| session.cache_limiter | "nocache" | PHP_INI_ALL | |
| session.cache_expire | "180" | PHP_INI_ALL | |
| session.use_trans_sid | "0" | PHP_INI_ALL | |
| session.trans_sid_tags | "a=href,area=href,frame=src,form=" | PHP_INI_ALL | Available as of PHP 7.1.0. |
| session.trans_sid_hosts | $_SERVER['HTTP_HOST'] |
PHP_INI_ALL | Available as of PHP 7.1.0. |
| session.sid_length | "32" | PHP_INI_ALL | Available as of PHP 7.1.0. |
| session.sid_bits_per_character | "4" | PHP_INI_ALL | Available as of PHP 7.1.0. |
| session.upload_progress.enabled | "1" | PHP_INI_PERDIR | |
| session.upload_progress.cleanup | "1" | PHP_INI_PERDIR | |
| session.upload_progress.prefix | "upload_progress_" | PHP_INI_PERDIR | |
| session.upload_progress.name | "PHP_SESSION_UPLOAD_PROGRESS" | PHP_INI_PERDIR | |
| session.upload_progress.freq | "1%" | PHP_INI_PERDIR | |
| session.upload_progress.min_freq | "1" | PHP_INI_PERDIR | |
| session.lazy_write | "1" | PHP_INI_ALL | |
| session.hash_function | "0" | PHP_INI_ALL | Removed as of PHP 7.1.0. |
| session.hash_bits_per_character | "4" | PHP_INI_ALL | Removed as of PHP 7.1.0. |
| session.entropy_file | "" | PHP_INI_ALL | Removed as of PHP 7.1.0. |
| session.entropy_length | "0" | PHP_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
string
session.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_handlers; registered handlers can be
obtained on a per-installation basis by referring to
phpinfo(). See also
session_set_save_handler().
session.save_path
string
session.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
string
session.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
bool
session.auto_start specifies whether the
session module starts a session automatically on request
startup. Defaults to 0 (disabled).
session.serialize_handler
string
session.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
int
session.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
int
session.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
int
session.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).
Note: If different scripts have different values of
session.gc_maxlifetimebut 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
string
session.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
string
session.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_filedefaults to/dev/urandomor/dev/arandomif it is available.
session.entropy_length
int
session.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
bool
session.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_modeis 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 involved 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. 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 sent the cookie for cross-domain GET requests, while Strict
will not.
session.cache_limiter
string
session.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
int
session.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
bool
session.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,
fieldsetis no longer considered as special tag.
session.trans_sid_hosts
string
session.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
int
session.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
int
session.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
mixed
session.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
int
session.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
bool
session.upload_progress.cleanup
bool
Note: 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
mixed
session.upload_progress.min_freq
int
session.lazy_write
bool
session.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.