Nginx module to use PAM for simple http authentication

:Date: $Date: 2010-11-15 12:35:32 +0100 (dl 15 de nov de 2010) $ :Revision: $Rev: 4488 $

Compilation

When compiling from source build as usual adding the -add-module option::

./configure --add-module=$PATH_TO_MODULE

If you are using a Debian GNU/Linux distribution is easy to build a modified package that includes this module::

Get the source

apt-get source nginx

Copy the module

NGINX_DEBIAN=$(ls -d nginx-*/debian) mkdir $NGINX_DEBIAN/ngx_http_auth_pam_module cp config $NGINX_DEBIAN/ngx_http_auth_pam_module/ cp ngx_http_auth_pam_module.c $NGINX_DEBIAN/ngx_http_auth_pam_module/ cd $NGINX_DEBIAN; cd ..;

Add the argument --add-module=./debian/ngx_http_auth_pam_module to the

./configure call on the debian/rules file

sed -i -e '/./configure .$/,/[^]$/ { /^.[^]$/ { s%^(.*)$% --add-module=./debian/ngx_http_auth_pam_module n1%; } }' debian/rules

Add the libpam-dev build dependency

sed -i -e 's/^Build-Depends: /Build-Depends: libpam-dev, /;' debian/control

Update the package version using the dch command from devscripts

dch -l'+authpam' 'Added ngx_http_auth_pam_module support'

Build the package

dpkg-buildpackage

And install

sudo dpkg -i ../nginx*deb

Configuration

The module only has two directives:

• auth_pam: This is the http authentication realm. If given the value off the module is disabled (needed when we want to override the value set on a lower-level directive).

• auth_pam_service_name: this is the PAM service name and by default it is set to nginx.

Examples

To protect everything under /secure you will add the following to the nginx.conf file::

location /secure { auth_pam "Secure Zone"; auth_pam_service_name "nginx"; }

Note that the module runs as the web server user, so the PAM modules used must be able to authenticate the users without being root; that means that if you want to use the pam_unix.so module to autenticate users you need to let the web server user to read the /etc/shadow file if that does not scare you (on Debian like systems you can add the www-data user to the shadow group).

As an example, to authenticate users against an LDAP server (using the pam_ldap.so module) you will use an /etc/pam.d/nginx like the following::

auth required /lib/security/pam_ldap.so account required /lib/security/pam_ldap.so

If you also want to limit the users from LDAP that can authenticate you can use the pam_listfile.so module; to limit who can access resources under /restricted add the following to the nginx.conf file::

location /restricted { auth_pam "Restricted Zone"; auth_pam_service_name "nginx_restricted"; }

Use the following /etc/pam.d/nginx_restricted file::

auth required /lib/security/pam_listfile.so onerr=fail item=user sense=allow file=/etc/nginx/restricted_users auth required /lib/security/pam_ldap.so account required /lib/security/pam_ldap.so

And add the users allowed to authenticate to the /etc/nginx/restricted_users (remember that the web server user has to be able to read this file).

PAM Environment

The plugin set's the following additional environment variables when using pam_exec.so as pam module for authentication:

REQUEST=GET /some/url?foo&bar HTTP/1.1
HOST=localhost:8000

You may use this information for request based authentication. You need a recent pam release (>= version 1.0.90) to expose environment variables to pam_exec (Ubuntu 8.04 has a too old pam version here!).

.. ...... .. SVN Id: $Id: README 4488 2010-11-15 11:35:32Z sto $