Where to put a PAM module?

Question

I'm currently trying to test a PAM module, this one: http://www.linux-pam.org/Linux-PAM-html/adg-example.html.

There is no indication about where to put the .o file.

I tried to put it in /lib/security and /usr/lib/security but it doesn't work.

I had no error while compiling:

$ gcc -fPIC -c check_user.c
$ ld -x --shared -o check_user.so check_user.o

As indicated, I put those lines in /etc/pam.d/check_user:

auth       required     pam_unix.so
account    required     pam_unix.so

It doesn't seem to work because when I try to log in with another account I don't have the message. What's wrong?

Answer 1

For those who want to create a PAM module, there is a very good example here: https://github.com/beatgammit/simple-pam.

In my case, the functions to call in my PAM module to exec something at login/logout are:

PAM_EXTERN int pam_sm_open_session(pam_handle_t *pamh, int  flags,int argc, const char **argv ) {
    printf("Connected\n");
    return PAM_SUCCESS;
}

PAM_EXTERN int pam_sm_close_session(pam_handle_t *pamh, int  flags,int argc, const char **argv ) {
    printf("Disconnected\n");
    return PAM_SUCCESS;
}

As indicated in the README, the so file needs to be put into /lib/security/.