If you need to validate a *real* unix password on a system using shadowed passwords, the posix_getpwnam() function in PHP won't work (as mentioned, 'x', or '*', will be in the password field).
I have a need to verify a user/pass within PHP (using SSL!). I don't know if this is the best way, but it's what I'm doing at the moment (works well!).
First, you need some help from the OS. I wrote a tiny C utility that does the shadow look-up for me... It requires root access to read /etc/shadow. So after you compile (gcc -O2 -s -o spasswd -lcrypt spasswd.c), you need to either use sudo to run it, or
# chown root spasswd && chmod u+s spasswd
To code that I'm using to authenticate a user/pass from PHP looks like:
function Authenticate($realm)
{
global $PHP_AUTH_USER;
global $PHP_AUTH_PW;
if(!isset($PHP_AUTH_USER))
{
header("WWW-Authenticate: Basic realm=\"$realm\"");
header("HTTP/1.0 401 Unauthorized");
return false;
}
else
{
if(($fh = popen("/usr/sbin/spasswd", "w")))
{
fputs($fh, "$PHP_AUTH_USER $PHP_AUTH_PW");
$r = pclose($fh);
if(!$r)
return true;
}
}
header("WWW-Authenticate: Basic realm=\"$realm\"");
header("HTTP/1.0 401 Unauthorized");
return false;
}
The C source for spasswd.c:
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <crypt.h>
#include <shadow.h>
static char salt[12], user[128], pass[128];
void die(void)
{
memset(salt, '\0', 12);
memset(user, '\0', 128);
memset(pass, '\0', 128);
}
int main(int argc, char *argv[])
{
struct spwd *passwd;
atexit(die); die();
if(fscanf(stdin, "%127s %127s", user, pass) != 2)
return 1;
if(!(passwd = getspnam(user)))
return 1;
strncpy(salt, passwd->sp_pwdp, 11);
strncpy(pass, crypt(pass, salt), 127);
if(!strncmp(pass, passwd->sp_pwdp, 127))
return 0;
return 1;
}
Hope this helps someone...
posix_getpwnam
(PHP 4, PHP 5, PHP 7, PHP 8)
posix_getpwnam — Restituisce informazioni su un utente dato il nome
Descrizione
La funzione restituisce un array associativo contenente le informazioni
sull'utente con nome specificato nel parametro
username.
Gli elementi dell'array sono:
| Elemento | Descrizione |
|---|---|
| name |
L'elemento name solitamente contiene il nome dell'utente. Questo
è un nome corto, di solito meno di 16 caratteri, non
il nome reale, completo, dell'utente. Questo dovrebbe essere uguale
al parametro username passato alla funzione
e quindi ridondante.
|
| passwd | L'elemento passwd contiene la password dell'utente in formato criptato. Spesso, ad esempio nei sistemi utilizzano password "shadow", vengono restituiti degli asterischi. |
| uid | ID dell'utente in formato numerico. |
| gid | ID del gruppo a cui appartiene l'utente. Utilizzare la funzione posix_getgrgid() per ottenere il nome del gruppo e l'elenco dei suoi membri. |
| gecos | GECOS è un termine obsoleto che si riferisce a campi del comando finger su sistemi Honeywell. Tuttavia il campo è sopravvissuto ed il suo contenuto è stato formalizzato in POSIX. Il campo contiene le informazioni separate da virgola relative a nome completo dell'utente, numero telefonico dell'ufficio, numero dell'ufficio, numero telefonico di casa. In molti sistemi è disponibile solo il nome completo dell'utente. |
| dir | Questo elemento contiene il percorso assoluto alla home directory dell'utente. |
| shell | L'elemento shell contiene il percorso assoluto alla shell di default per l'utente. |
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User Contributed Notes 9 notes
darryl at pointclark dot net ¶
23 years ago
bau at kg-fds dot de ¶
18 years ago
If you are running a pop3-daemon, so you can do authentification on pop3 by using fsockopen :-) and checking whether it returns +OK or -ERR
corychristison at lavacube dot net ¶
20 years ago
For those of you who are writing daemons with PHP and are one for security. This function will not return any info if you have called PHP's chroot() function.
Took me a few minutes why it wouldn't find the user it was searching for.
marcus at nospamsynchromedia dot co dot uk ¶
22 years ago
Given a non-existent username, this function returns a boolean FALSE.
perreal at lyon dot cemagref dot fr ¶
22 years ago
To check passwords on a Unix-box, look at the mod_auth_external module for Apache, it uses external programs to do the real job. The server won't ever read the encrypted password.
One of them, pwauth, can be configured to use PAM or whatever is used on your system. Users that can run this program are configured at compile time. And this program can be called from PHP with exec(...).
vision_1967 at hotmail dot com ¶
23 years ago
I needed to get access to the user information to do login/validation via an SSL connection and encountered the same problem with receiving '*' in the password field. After checking the documentation on posix_getpwnam, I saw a previous solution involving coding a C program. This was a bit bulky for me so I came up with my own solution.
Variations on this theme can probably be done to make the solution more programmer/reader friendly, but the way I did it accomplished the task that I needed to do.
IF the information you need to get from posix_getpwnam comes from a host participating in an NIS network, you can accomplish the same thing with the following command:
$autharray = split(":",`ypmatch $USER passwd`);
(pretty long explanation for such a short solution huh?)
You'll have to get at the fields by their index number ($autharray[0], $autharray[1], ...) using this method.
To create an associative array that is plug-in compatible with the posix_getpwnam function, you'll probably need to use the 'list' specifier to do the assignments.
I hope this helps someone.
--S
sezery at damla dot net ¶
23 years ago
User and group functions do not work on recent Redhat systems since these functions are based on /etc/group file but new redhat does not put group members' list into this file. Instead you need to examine /etc/passwd file and find members of a group by checking group id.
bau at kg-fds dot de ¶
18 years ago
Hello, I've tried another, more easier way to check passwords than checking it to a pop3-server. If you are running a samba-server or a Windows PDC, so you can try to connect with the username/password you want to check to the netlogon of this server:
if (exec('echo "exit"|smbclient //server/netlogon -U'.$user.' '.$pass)=="") { ... }
If the username/password doesn't match, then the exec-command under LINUX returns an error.
Good luck
Baumg?rtner
bau at kg-fds dot de ¶
18 years ago
Oh I forgot the following:
to change a Users password via PHP,
you can use the following (under Linux with installed Samba):
exec('echo -e "'.$oldpassword.'\n'.$newpassword.'\n'.$newpassword.'
"|smbpasswd -U'.$user.' -s')
The exec-command returns ""
if an error occured (then see the error_log of the web-server)
or a message "The password has been changed".
Good luck.
Baumg?rtner
