Graham Ollis > PlugAuth-0.26 > PlugAuth::Guide::Client

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NAME ^

PlugAuth::Guide::Client - Guide for authenticating and authorizing against a PlugAuth server

VERSION ^

version 0.26

DESCRIPTION ^

This document contains some common recipes for using interacting as a client in various environments with a PlugAuth server.

This document assumes a PlugAuth server listening on http://localhost:3000 with users primus (an administrator) with password "spark" and optimus (a user) with password "matrix". The resource.txt file for the server looks like this:

 / (accounts): primus
 /user (change_password): primus
 /user/#u (change_password): #u
 /some/user/resource (GET): optimus

For details on setting up a PlugAuth server using the default plugins, see PlugAuth::Guide::Server. All of these examples are included with the PlugAuth distribution in example directory.

From a Clustericious service using Clustericious::Plugin::PlugAuth.

Any Clustericious service can be integrated with PlugAuth using the Clustericious PlugAuth plugin. Here is an example Routes module

 package ExampleAppExample::Routes;
 
 use Clustericious::RouteBuilder;
 
 get '/' => sub { shift->render_text('hello') };
 
 authenticate;
 authorize;
 
 get '/some/user/resource' => sub { shift->render_text('hello') };

And example configuration to go along with it.

 ---
 url: http://localhost:3001
 plug_auth:
   url: http://localhost:3000

This will configure the example application to listen on localhost port 3001 and to use the PlugAuth server listening on localhost port 3000. You can start this service by using the daemon command

 % perl ExampleAppExample.pl daemon -l http://localhost:3001

And test it by navigating your browser to http://localhost:3001/some/user/resource . The web browser should prompt you for a username and password, and accept the credentials for optimus.

For more details see Clustericious::Plugin::PlugAuth.

From Perl using PlugAuth::Client

PlugAuth::Client can be used to authenticate against a PlugAuth server from a Perl script or module. PlugAuth::Client needs a configuration file, just like PlugAuth. You can use the same configuration file as you use for the server, although the only configuration item you need is url:

 ---
 url: http://localhost:3000

First you will need t ocreate an instance of PlugAuth::Client:

 use strict;
 use warnings;
 use v5.10;
 use PlugAuth::Client;
 
 my $client = PlugAuth::Client->new;

Then you should specify your credentials using the login method. login doesn't connect to the PlugAuth server itself, but it does remember the credentials and use it on the next call that you make to the PlugAuth server.

 print "user: ";
 my $username = <STDIN>;
 print "pass: ";
 my $password = <STDIN>;
 
 chomp $username;
 chomp $password;
 
 $client->login($username, $password);

Obviously in a production environment you should hide the password when prompting for a password, but for this example, it will be helpful to see the credentials at the shell.

To check that the credentials are correct, you can use the auth method:

 if($client->auth)
 {
   say "$username is authenticated";
 }
 else
 {
   say "AUTH FAILED";
 }

And to check that you are authorized for a particular resource, use the authz method:

 if($client->authz($username, 'GET', '/some/user/resource'))
 {
   say "$username is authorized to GET /some/user/resource";
 }
 else
 {
   say "AUTHZ FAILED";
 }

Here we run this example script using bogus credentials:

 % perl client.pl
 user: bogus
 pass: bogus
 AUTH FAILED
 AUTHZ FAILED

Next, try the user administrator credentials. Note that although primus is an administrator for users we did not give him permission to get the resource /some/user/resource, so the authorization fails.

 % perl client.pl
 user: primus
 pass: spark
 primus is authenticated
 AUTHZ FAILED

Finally, providing the credentials for optimus should pass both authentication and authorization.

 % perl client.pl
 user: optimus
 pass: matrix
 optimus is authenticated
 optimus is authorized to GET /some/user/resource

There are a number of other features that can be accessed using this interface. Please see PlugAuth::Client for details.

From the command line using plugauthclient and plugauthpasswd.

The PlugAuth::Client distribution installs two programs for interacting with a PlugAuth server from the command line. plugauthclient is a thin wrapper around the Perl and RESTful APIs provided by PlugAuth. As in the previous example, we need a configuration file in ~/etc/PlugAuth.conf, but only the url needs to be specified for the client. Once that is setup we can check authentication and authorization, just like we could via the Perl API.

 % plugauthclient auth
 Username for  at localhost :  [default joe] bogus
 Password: 
 [ERROR] 2012/11/30 12:17:16 Client.pm (733) Error trying to GET http://user:*****@localhost:3000/auth : 403 Forbidden
 [ERROR] 2012/11/30 12:17:16 Client.pm (737) not ok
 [ERROR] 2012/11/30 12:17:16 Command.pm (253) Forbidden
 % plugauthclient auth
 Username for  at localhost :  [default joe] optimus
 Password: 
 --- ok
 % plugauthclient authz primus GET /some/user/resource
 [ERROR] 2012/11/30 12:19:11 Client.pm (733) Error trying to GET http://localhost:3000/authz/user/primus/GET/some/user/resource : 403 Forbidden
 [ERROR] 2012/11/30 12:19:11 Client.pm (737) unauthorized : primus cannot GET /some/user/resource
 [ERROR] 2012/11/30 12:19:11 Command.pm (253) Forbidden
 % plugauthclient authz optimus GET /some/user/resource
 --- ok

plugauthpasswd provides a mechanism for changing your password:

 % plugauthpasswd
 Username:  [default joe] optimus
 Old Password:
 New Password:
 Verify New Password:
 --- ok

From another language using a WWW library

The RESTful API for PlugAuth is documented in PlugAuth::Routes. For authentication simply make a HTTP GET request to http://localhost:3000/auth using HTTP BASIC authentication. To check authorization make a HTTP GET request to http://localhost:3000/authz/user/username/action/resource . For example to check that optimus can GET on the resource /some/user/resource, the constructed resource would be http://localhost:3000/authz/user/primus/GET/some/user/resource . All routes in the RESTful API return standard HTTP status codes.

From a sh script using wget

If you do not have PlugAuth::Client installed and cannot install it, you can use wget or curl. Because PlugAuth uses standard HTTP status codes, wget will return non zero on failure and you can construct an if around it.

 #!/bin/sh
 
 USER=$1
 PASS=$2
 WGET="wget -q -O /dev/null"
 
 if $WGET http://${USER}:${PASS}@localhost:3000/auth ; then
   echo "$USER is authenticate"
 else
   echo "AUTH FAILED"
 fi
 
 if $WGET http://localhost:3000/authz/user/${USER}/GET/some/user/resource ; then
   echo "$USER is authorized to GET /some/user/resource"
 else
   echo "AUTHZ FAILED"
 fi

Here we pass it bogus credentials

 % sh client.sh bogus bogus
 AUTH FAILED
 AUTHZ FAILED

And here we pass it good credentials

 % sh client.sh optimus matrix
 optimus is authenticate
 optimus is authorized to GET /some/user/resource

From PAM (Pluggable Authentication Module)

There is a PAM module that will authenticate against a HTTP server using HTTP Basic authentication on git. It is licensed under the MIT License and is based on work by Kragen Sitaker. I had to install libpam0g-dev and libcurl4-openssl-dev on my Debian system in order for it to build for me.

 % git clone git://github.com/beatgammit/pam-http.git
 % cd pam-http
 % make
 % sudo cp mypam.so /lib/security

Add these two lines to the top of your /etc/pam.d/common-auth (or other) config:

 auth sufficient mypam.so url=http://localhost:3000/auth
 account sufficient mypam.so

sufficient means that it will fallback on your existing passwd file or whatever authentication mechanism is configured already. Change the url argument to the URL for your PlugAuth server.

There are numerous caveats here. PlugAuth usually runs as an unprivileged user which means it binds to an unprivileged port, and if an unauthorized user sets up their own PlugAuth service before the "correct" PlugAuth server starts, authentication could be subverted. Encryption, such as SSL should be used if you are authenticating against a PlugAuth server over the network, but pam-http as written does not check the authenticity of the PlugAuth server's SSL certificate. Unix accounts require more information than just authentication, which is not provided by PlugAuth, so something like LDAP may be more appropriate. None of these things are insurmountable if you take the time to fix them, but care needs to be taken.

SEE ALSO ^

PlugAuth, PlugAuth::Client, Authen::Simple::PlugAuth

AUTHOR ^

Graham Ollis <gollis@sesda3.com>

COPYRIGHT AND LICENSE ^

This software is copyright (c) 2012 by NASA GSFC.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

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