NAME

Net::Radius::PacketOrdered - interface to RADIUS packets with proxy states

SYNOPSIS

use Net::Radius::PacketOrdered;
use Net::Radius::Dictionary;

my $d = new Net::Radius::Dictionary "/etc/radius/dictionary";

my $p = new Net::Radius::PacketOrdered $d, $data;
$p->dump;

if ($p->attr('User-Name' eq "lwall") {
  my $resp = new Net::Radius::PacketOrdered $d;
  $resp->set_code('Access-Accept');
  $resp->set_identifier($p->identifier);
  $resp->set_authenticator($p->authenticator);
  $resp->set_attr('Reply-Message' => "Welcome, Larry!\r\n");
  my $respdat = auth_resp($resp->pack, "mysecret");
  ...

DESCRIPTION

RADIUS (RFC2865) specifies a binary packet format which contains various values and attributes. Net::Radius::PacketOrdered provides an interface to turn RADIUS packets into Perl data structures and vice-versa.

Net::Radius::PacketOrdered does not provide functions for obtaining RADIUS packets from the network. A simple network RADIUS server is provided as an example at the end of this document.

Proxy-State, RFC specification

from RFC 2865 - ftp://ftp.rfc-editor.org/in-notes/rfc2865.txt

2. Operation

If any Proxy-State attributes were present in the Access-Request, they MUST be copied unmodified and in order into the response packet. Other Attributes can be placed before, after, or even between the Proxy-State attributes.

2.3 Proxy

The forwarding server MUST treat any Proxy-State attributes already in the packet as opaque data. Its operation MUST NOT depend on the content of Proxy-State attributes added by previous servers.

If there are any Proxy-State attributes in the request received from the client, the forwarding server MUST include those Proxy-State attributes in its reply to the client. The forwarding server MAY include the Proxy-State attributes in the access-request when it forwards the request, or MAY omit them in the forwarded request. If the forwarding server omits the Proxy-State attributes in the forwarded access-request, it MUST attach them to the response before sending it to the client.

Proxy-State, Implementation

Proxy-State attributes are stored in an array, and when copied from one Net::Radius::PacketOrdered to another - using method new with packet data as attribute - they retain their order.

attr method always returns last attribute inserted.

set_attr method pushed name attribute onto the Attributes stack, or overwrites it in specific circumnstances, as described in method documentation.

PACKAGE METHODS

new Net::Radius::PacketOrdered $dictionary, $data

Returns a new Net::Radius::PacketOrdered object. $dictionary is an optional reference to a Net::Radius::Dictionary object. If not supplied, you must call set_dict. If $data is supplied, unpack will be called for you to initialize the object.

OBJECT METHODS

There are actually two families of object methods. The ones described below deal with standard RADIUS attributes. An additional set of methods handle the Vendor-Specific attributes as defined in the RADIUS protocol. Those methods behave in much the same way as the ones below with the exception that the prefix vs must be applied before the attr in most of the names. The vendor code must also be included as the first parameter of the call.

The vsattr and set_vsattr methods, used to query and set Vendor-Specific attributes return an array reference with the values of each instance of the particular attribute in the packet. This difference is required to support multiple VSAs with different parameters in the same packet.

->set_dict($dictionary)

Net::Radius::PacketOrdered needs access to a Net::Radius::Dictionary object to do packing and unpacking. set_dict must be called with an appropriate dictionary reference (see Net::Radius::Dictionary) before you can use ->pack or ->unpack.

->code

Returns the Code field as a string. As of this writing, the following codes are defined:

Access-Request          Access-Accept
Access-Reject           Accounting-Request
Accounting-Response     Access-Challenge
Status-Server           Status-Client

-><set_code>($code)

Sets the Code field to the string supplied.

->identifier

Returns the one-byte Identifier used to match requests with responses, as a character value.

->set_identifier

Sets the Identifier byte to the character supplied.

->authenticator

Returns the 16-byte Authenticator field as a character string.

->set_authenticator

Sets the Authenticator field to the character string supplied.

->set_attr($name, $val, $rewrite_flag)

Sets the named Attributes to the given value. Values should be supplied as they would be returned from the attr method. If rewrite_flag is set, and a single attribute with such name already exists on the Attributes stack, its value will be overwriten with the supplied one. In all other cases (if there are more than one attributes with such name already on the stack, there are no attributes with such name, rewrite_flag is omitted) name/pair array will be pushed onto the stack.

->attributes

Retrieves a list of attribute names present within the packet.

->attr($name)

Retrieves the value of the named Attribute. If there are multiple values for the Attribute, last one inserted will be returned. This is behaviour is crucial for correct implementation of Proxy-State.

->unset_attr($name,$value)

Removes given Attribute with given value from the Attributes stack.

->attr_slot($integer)

Retrieves the attribute value of the given slot number from the Attributes stack.

->unset_attr_slot($integer)

Removes given stack position from the Attributes stack.

->password($secret)

The RADIUS User-Password attribute is encoded with a shared secret. Use this method to return the decoded version. This also works when the attribute name is 'Password' for compatibility reasons.

->set_password($passwd, $secret)

The RADIUS User-Password attribute is encoded with a shared secret. Use this method to prepare the encoded version. Note that this method always stores the encrypted password in the 'User-Password' attribute. Some servers have been reported on insisting on this attribute to be 'Password' instead.

->show_unknown_entries($bool)

Controls the generation of a warn() whenever an unknown tuple is seen.

->acct_request_auth($packet, $secret)

Set request authenticator in binary packet, for accounting request authentication.

->acct_response_auth($packet, $secret, request-auth)

Set reponse authenticator in binary packet, for accounting response authentication.

->dump

Prints the content of the packet to STDOUT.

->pack

Returns a raw RADIUS packet suitable for sending to a RADIUS client or server.

->unpack($data)

Given a raw RADIUS packet $data, unpacks its contents so that they can be retrieved with the other methods (code, attr, etc.).

EXPORTED SUBROUTINES

auth_resp($packed_packet, $secret)

Given a (packed) RADIUS packet and a shared secret, returns a new packet with the Authenticator field changed in accordace with RADIUS protocol requirements.

NOTES

This document is (not yet) intended to be a complete description of how to implement a RADIUS server. Please see the RFCs (at ftp://ftp.livingston.com/pub/radius/) for that. The following is a brief description of the procedure:

1. Receive a RADIUS request from the network.
2. Unpack it using this package.
3. Examine the attributes to determine the appropriate response.
4. Construct a response packet using this package.
   Copy the Identifier and Authenticator fields from the request,
   set the Code as appropriate, and fill in whatever Attributes
   you wish to convey in to the server.
5. Call the pack method and use the auth_resp function to
   authenticate it with your shared secret.
6. Send the response back over the network.
7. Lather, rinse, repeat.

EXAMPLE

    #!/usr/local/bin/perl -w

    use Net::Radius::Dictionary;
    use Net::Radius::PacketOrdered;
    use Net::Inet;
    use Net::UDP;
    use Fcntl;
    use strict;

    # This is a VERY simple RADIUS authentication server which responds
    # to Access-Request packets with Access-Accept.  This allows anyone
    # to log in.

    my $secret = "mysecret";  # Shared secret on the term server

    # Parse the RADIUS dictionary file (must have dictionary in current dir)
    my $dict = new Net::Radius::Dictionary "dictionary"
      or die "Couldn't read dictionary: $!";

    # Set up the network socket (must have radius in /etc/services)
    my $s = new Net::UDP { thisservice => "radius" } or die $!;
    $s->bind or die "Couldn't bind: $!";
    $s->fcntl(F_SETFL, $s->fcntl(F_GETFL,0) | O_NONBLOCK)
      or die "Couldn't make socket non-blocking: $!";

    # Loop forever, recieving packets and replying to them
    while (1) {
      my ($rec, $whence);
      # Wait for a packet
      my $nfound = $s->select(1, 0, 1, undef);
      if ($nfound > 0) {
	# Get the data
	$rec = $s->recv(undef, undef, $whence);
	# Unpack it
	my $p = new Net::Radius::PacketOrdered $dict, $rec;
	if ($p->code eq 'Access-Request') {
	  # Print some details about the incoming request (try ->dump here)
	  print $p->attr('User-Name'), " logging in with password ",
		$p->password($secret), "\n";
	  # Create a response packet
	  my $rp = new Net::Radius::PacketOrdered $dict;
	  $rp->set_code('Access-Accept');
	  $rp->set_identifier($p->identifier);
	  $rp->set_authenticator($p->authenticator);
	  # (No attributes are needed.. but you could set IP addr, etc. here)
	  # Authenticate with the secret and send to the server.
	  $s->sendto(auth_resp($rp->pack, $secret), $whence);
	}
	else {
	  # It's not an Access-Request
	  print "Unexpected packet type recieved.";
	  $p->dump;
	}
      }
    }

RADIUS PROXY EXAMPLE

See README.proxy for how to setup a test consisting of radius client, server and multiple proxies inbetween, all using this module and FreeRadius. Scripts for all components (client/server/proxies) in the test setup are provided in the CPAN distribution of the module.

About the stability, this code has been in very active use since early 2004 on a network with 8000+ edge devices without a single problem encountered so far. It has been succesfully used under FreeBSD and Linux.

AUTHOR

Christopher Masto, <chris@netmonger.net>. VSA support by Luis E. Muñoz, <luismunoz@cpan.org>. Fix for unpacking 3COM VSAs contributed by Ian Smith <iansmith@ncinter.net>. Information for packing of 3Com VSAs provided by Quan Choi <Quan_Choi@3com.com>. Some functions contributed by Tony Mountifield <tony@mountifield.org>.

Extension of Net:Radius::Packet into Net:Radius::PacketOrdered to include the ability to implement correctly Proxy-State by Toni Prug, <toni@irational.org>, idea by Bill Hulley.

COPYRIGHT

Original work (c) Christopher Masto. Changes (c) 2002,2003 Luis E. Muñoz <luismunoz@cpan.org>. PacketOrdered additions/changes (c) 2004 Toni Prug. All rights reserved.

This package is free software and is provided "as is" without expressed or implied warranty. It may be used, redistributed and/or modified under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html

SEE ALSO

Net::Radius::Dictionary Net::Radius::Packet

cpanm Net::Radius::PacketOrdered

perl -MCPAN -e shell
install Net::Radius::PacketOrdered