<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <HTML> <HEAD> <META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9"> <TITLE>The Linux-PAM Module Writers' Guide: Introduction</TITLE> <LINK HREF="pam_modules-2.html" REL=next> <LINK HREF="pam_modules.html#toc1" REL=contents> </HEAD> <BODY> <A HREF="pam_modules-2.html">Next</A> Previous <A HREF="pam_modules.html#toc1">Contents</A> <HR> <H2><A NAME="s1">1. Introduction</A></H2> <H2><A NAME="ss1.1">1.1 Synopsis</A> </H2> <P> <BLOCKQUOTE><CODE> <PRE> #include <security/pam_modules.h> gcc -fPIC -c pam_module-name.c ld -x --shared -o pam_module-name.so pam_module-name.o </PRE> </CODE></BLOCKQUOTE> <P> <H2><A NAME="ss1.2">1.2 Description</A> </H2> <P><B>Linux-PAM</B> (Pluggable Authentication Modules for Linux) is a library that enables the local system administrator to choose how individual applications authenticate users. For an overview of the <B>Linux-PAM</B> library see the <B>Linux-PAM</B> System Administrators' Guide. <P> <P>A <B>Linux-PAM</B> module is a single executable binary file that can be loaded by the <B>Linux-PAM</B> interface library. This PAM library is configured locally with a system file, <CODE>/etc/pam.conf</CODE>, to authenticate a user request via the locally available authentication modules. The modules themselves will usually be located in the directory <CODE>/usr/lib/security</CODE> and take the form of dynamically loadable object files (see dlopen(3)). Alternatively, the modules can be statically linked into the <B>Linux-PAM</B> library; this is mostly to allow <B>Linux-PAM</B> to be used on platforms without dynamic linking available, but the two forms can be used together. It is the <B>Linux-PAM</B> interface that is called by an application and it is the responsibility of the library to locate, load and call the appropriate functions in a <B>Linux-PAM</B>-module. <P> <P>Except for the immediate purpose of interacting with the user (entering a password etc..) the module should never call the application directly. This exception requires a "conversation mechanism" which is documented below. <P> <HR> <A HREF="pam_modules-2.html">Next</A> Previous <A HREF="pam_modules.html#toc1">Contents</A> </BODY> </HTML>
