Best way to check for system user and password in C

Applications Programming
1

Hello,

I'm implementing a very simple FTP client, and to do the login I would like to check against system users instead of using my own database, so that I can give the proper permissions to the newly created process that I spawn with fork. What's the best way for doing this in C?

I've read about the getpwnam function, that returns a struct passwd that has the field pw_passwd to compare against (using the crypt function), but I'm not sure if this is quite standard, is there any other way to do this?

Thanks, Roger.

2

I would suggest to use PAM , instead of reinventing the wheel .

The pam_authenticate function is used to authenticate the current user.

#include <security/pam_appl.h>
int pam_authenticate (pam_handle_t *pamh, int flags);

Google for
Linux-PAM Application Developers' Guide

3

Thanks, I've already got a code sample from CryptNoMore

4

OK , but if you want it portable among Unixes , PAM is the way.

5

Yes, CryptNoMore shows examples about how to use OpenDirectory, PAM and Crypt. I've used the PAM part of the code, which runs fine on both Mac OS X and Linux at least.

Thanks for the reply.