is there a login service?

[capitano]

I'm writing an application for RH7.1 Linux which should require authentication against user shell account. Instead of writing my own script to parse both the /etc/passwd and /etc/shadow to compare username and MD5 passwords, I'd like to find an application/service which already does this. I could wrap my application around this pre-existing service.

How does telnet, ssh, and etc run username/passwd checks? Don't they wrap around a pre-existing service? Or do they REALLY do all this parsing by their lonely old selves?

Does anybody know of a service to authenticate against user shell login/passwds which I can use??

Anybody, Anybody?

Thanks!!!

 

[ifincham]

Hi,

Its all done with PAM (Pluggable Authentication Modules). Once PAM is active requests for resources are run through a series of rules defined by a config file in the /etc/pam.d directory. For example, /etc/pam.d/login . PAM config files look like this :

#%PAM-1.0
auth required /lib/security/pam_securetty.so
auth required /lib/security/pam_unix.so shadow nullok
auth required /lib/security/pam_nologin.so
account required /lib/security/pam_unix.so
password required /lib/security/pam_cracklib.so
password required /lib/security/pam_unix.so shadow nullok use_authtok
session required /lib/security/pam_unix.so

What happens is each module is called and conditions tested. Frequently they have their own config files. For example the module pam_securetty.so is the one that restricts root access to any tty other than those listed in /etc/securetty . The main site for info on PAM is here -->

http://www.kernel.org/pub/linux/libs/pam/

.

A bit more helpful for a newbie are the redhat docs -->

http://www.europe.redhat.com/documentation/HOWTO/User-Authentication-HOWTO/x101.php3

and also -->

http://www.redhat.com/docs/manuals/linux/RHL-7.1-Manual/ref-guide/s1-pam-config-files.html

Because of this modular design, you can write pretty much any add-on authorisation modules you like and use the PAM mechanism to apply them. The module writer's guide is here -->

http://www.kernel.org/pub/linux/libs/pam/Linux-PAM-html/pam_modules.html

.


Hope this helps