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README
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API
bool pam_auth(string $username, string $password [, string &$error [ $checkacctmgmt = true ] ])
bool pam_chpass(string $username, string $oldpassword, string $newpassword [, string &$error ])
The parameters are
username - Username to check
password - User supplied password
error - Output parameter to put any error messages in
checkacctmgmt - Call pam_acct_mgmt() to check account expiration and access hours (requires root access!)
oldpassword - Current password on account
newpassword - Password to change to
INSTALLATION
For pam_auth to work, pam must know about the php service.
For the module itself, the only real configuration is the servicename. By
default, this is set to php. It can be changed by adding the following to your
php.ini:
pam.servicename = "php";
Next, you'll need to create a pam service file for php. If you are on linux,
you'll need to create the file /etc/pam.d/php. You can copy another one to work
off of (/etc/pam.d/login is a good choice).
Some examples that should work:
on linux:
# /etc/pam.d/php
#
# note: both an auth and account entry are required
auth sufficient /lib/security/pam_pwdb.so shadow nodelay
account sufficient /lib/security/pam_pwdb.so
on solaris:
# add to /etc/pam.conf
php auth requisite /usr/lib/security/pam_authtok_get.so.1
php auth required /usr/lib/security/pam_unix_auth.so.1
php account required /usr/lib/security/pam_unix_account.so.1
These would authenticate out of the unix password and shadow file. However
please checking other /etc/pam.d/ entries, as the libraries these examples
point to may not be correct.
FAQ
* What is PAM?
PAM stands for Pluggable Authentication Module. It is a system that abstracts
user authentication to allow arbitrary modules to handle the real work. In this
way, pam enabled services can use a variety of complex authentication schemes
without modifying the applications. For more Information, and available
modules, see http://www.kernel.org/pub/linux/libs/pam/.
* Why would I want to use PAM from PHP?
PAM gives you very flexible control over authentication. As an example, there
are PAM modules that will authenticate against a local shadow or password file,
a Windows NT domain, an SQL database, LDAP, Kerberos, Radius, and more. In
addition, pam modules can give you the ability to have restrictions on the
authentication, such as the pam_tally module which limits the number of login
attempts, and the pam_listfile which let's you restrict access to a list of
users. Please note, using pam does not mean you can securely authenticate
users, it simply gives you the ability to do so with proper configuration and
planning.
* How can I get pam?
If you are running linux or solaris, you already have it! Linux and Solaris
both natively use pam for all authentication, so you're are all set. If you are
on other systems, well, you're on your own. I have no idea what PAM has been
ported too...
* I'm getting an Authentication Failure error, why?
Try setting the $checkacctmgmt parameter to false to skip the pam_acct_mgmt()
call, note that this only checks the password and skips performing account
validation such as account expiration and access. Otherwise see below.
The most likely reason for this is that you are trying to authenticate via a
local shadow file and you do not have permission to do so. The PAM modules
handling shadow authentication (used on Linux and Solaris) require that the
application have permission to read the shadow file (makes sense, eh?). If you
are running php as a cgi or as a webserver module, it is executed as your
webservers user and group.
By default, most Linux and Solaris systems are configured to only allow the root
user to read the shadow file. The recommended
way around this is to change permissions on the shadow file so that it is group
readable, and chgrp the file to the a group that the webserver is in. Before
doing this, you should give it some serious thought as allowing your webserver
to read the shadow file gives hackers another way to crack away at your system.
If you decide to enable this, I stronly suggest usage of the pam_tally module
to limit failed logins to a reasonable number of attempts, and one of the other
modules which will allow you to block root and other system users.
* The pam_auth function doesn't return anything, whattup?
Did you remember to create an entry in the pam configuration for the php
service?
* Logs indicate pam authenticated the user, but the function doesn't return
true, what gives?
Make sure your pam configuration has an entry for both auth and account, if you
do not have both, it will not work.