For further details and definition of the PHP_INI_* constants see
ini_set.
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_handlerstringsession.save_handler defines the name of the
handler which is used for storing and retrieving data
associated with a session. Defaults to
files. See also
session_set_save_handler.
session.save_pathstringsession.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. Defaults to
/tmp. 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. 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;.
If you leave this 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.
Prior to PHP 4.3.6, Windows users had to change this variable in order
to use PHP's session functions. A valid path must be specified, e.g.:
c:/temp.
session.namestringsession.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_startbooleansession.auto_start specifies whether the
session module starts a session automatically on request
startup. Defaults to 0 (disabled).
session.serialize_handlerstringsession.serialize_handler defines the name
of the handler which is used to serialize/deserialize
data. Currently, a PHP internal format (name
php) and WDDX is supported (name
wddx). WDDX is only available, if PHP is
compiled with WDDX
support. Defaults to php.
session.gc_probabilityintegersession.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_divisorintegersession.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_maxlifetimeintegersession.gc_maxlifetime specifies the number
of seconds after which data will be seen as 'garbage' and
cleaned up.
If you are using the default file-based session handler, your
filesystem must keep track of access times (atime). Windows FAT does
not so you will have to come up with another way to handle garbage
collecting your session if you are stuck with a FAT filesystem or any
other fs where atime tracking is not available.
Since PHP 4.2.3 it has used mtime (modified date) instead of atime. So, you
won't have problems with filesystems where atime tracking is not available.
session.referer_checkstringsession.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_filestringsession.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.
session.entropy_lengthintegersession.entropy_length specifies the number
of bytes which will be read from the file specified
above. Defaults to 0 (disabled).
session.use_cookiesbooleansession.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_cookiesbooleansession.use_only_cookies specifies whether
the module will only use
cookies to store the session id on the client side. Defaults
to 0 (disabled, for backward compatibility).
Enabling this setting prevents attacks involved passing session
ids in URLs. This setting was added in PHP 4.3.0.
session.cookie_lifetimeintegersession.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.
session.cookie_pathstringsession.cookie_path specifies path to set
in session_cookie. Defaults to /. See also
session_get_cookie_params and
session_set_cookie_params.
session.cookie_domainstringsession.cookie_domain specifies the domain to
set in session_cookie. Default is none at all. See also
session_get_cookie_params and
session_set_cookie_params.
session.cookie_securebooleansession.cookie_secure specifies whether
cookies should only be sent over secure connections. Defaults to
off.
This setting was added in PHP 4.0.4. See also
session_get_cookie_params and
session_set_cookie_params.
session.cache_limiterstringsession.cache_limiter specifies cache
control method to use for session pages
(none/nocache/private/private_no_expire/public). Defaults to
nocache. See also
session_cache_limiter.
session.cache_expireintegersession.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_sidbooleansession.use_trans_sid whether transparent
sid support is enabled or not. Defaults to
0 (disabled).
For PHP 4.1.2 or less, it is enabled by compiling with
--enable-trans-sid.
From PHP 4.2.0, trans-sid feature is always compiled.
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.
session.bug_compat_42boolean
PHP versions 4.2.0 and lower have an undocumented feature/bug that
allows you to to initialize a session variable in the global scope,
albeit register_globals
is disabled. PHP 4.3.0 and later will warn you, if this feature is
used, and if
session.bug_compat_warn is also enabled.
session.bug_compat_warnboolean
PHP versions 4.2.0 and lower have an undocumented feature/bug that
allows you to to initialize a session variable in the global scope,
albeit register_globals
is disabled. PHP 4.3.0 and later will warn you, if this feature is
used by enabling both
session.bug_compat_42
and
session.bug_compat_warn.
session.hash_functionintegersession.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).
This was introduced in PHP 5.
session.hash_bits_per_characterintegersession.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, "-", ",").
This was introduced in PHP 5.
url_rewriter.tagsstringurl_rewriter.tags specifies which HTML tags
are rewritten to include session id if transparent sid support
is enabled. Defaults to
a=href,area=href,frame=src,input=src,form=fakeentry,fieldset=
If you want XHTML conformity, remove the form entry and
use the <fieldset> tags around your form fields.
The track_vars and
register_globals
configuration settings influence how the session variables get
stored and restored.
As of PHP 4.0.3, track_vars is
always turned on.