
		FreeRADIUS as a proxy RADIUS server.


0. INTRODUCTION

  It is possible to use FreeRADIUS as a proxy RADIUS server. This
  means that it can consult a remote RADIUS server to validate a user.
  This is handy for roaming setups, or for renting ports to someone else.

1. FILES

  If a user logs in with a defined realm syntax, the "realm" portion is
  matched against the configuration to determine how the request should
  be handled.  Common realm formats are:

                username@realm
                realm/username
		username%realm
		realm\username

  The realm parsing syntax ( and search order ) is user definable via the
  realm module config in the /etc/raddb/radiusd.conf configuration file.

  You can define multiple instances of the realm module to support multiple
  realm syntax's at the same time.  Be sure to pay close attention to the
  search order that you define, as you may inadvertently get unexpected
  behaviour ( by having a user use 'realm1/username@realm2' for instance ).
  If you need to proxy to IPASS, it should go first, because usernames will
  be in the form IPASS/username@realm and you want to proxy these users to
  IPASS, not to the realm behind the @.

  The realms are configured in the file /etc/raddb/proxy.conf, which is
  included by radiusd.conf. The formats and sample configurations are
  included as comments.

  The realm "DEFAULT" (without the quotes) matches all realms.
  The realm "NULL" matches any requests WITHOUT a realm.

  If you set the remote server to "LOCAL", the request will be handled
  locally as usual, without sending it to a remote radius server.

  There are several options you can add in both files:

  - nostrip:
    By default the realm is stripped from the username before sending it
    on to the remote radius server. By specifying the "nostrip" option
    the @realm suffix will not be stripped.
  - hints
    By default the original username is sent to the remote radius
    server. By specifying the "hints" option the username will be
    sent as it is after the "hints" file was processed.
  - notrealm:
    By default if a realm is matched, it will be proxied to the server
    specified.  However, if you are using Replication functionality, you
    may want to override this behaviour.  This option will prevent a
    user who enters 'user@foobar' from being proxied if the 'foobar'
    realm configuration contains 'notrealm'.  This function used to be
    called 'notsuffix', and the old syntax is still supported.

  The /etc/raddb/realms file is deprecated and should not be used anymore.
  If you use the /etc/raddb/realms file to enter realm configurations you will
  need to add the hostname and secret for the remote server in the
  file /etc/raddb/clients.
  It is not recommended to use both the realms file and the proxy.conf file,
  as that could cause confusion.

2. ACCOUNTING

  All accounting data for proxied requests does NOT get stored in the
  standard logfiles, but in a separate directory. The name of this
  directory is the name of the remote radius server, and if you want you
  can define a nickname for it in /etc/raddb/naslist just as for normal NASes.

3. REMOTE SERVER

  When your server proxies requests to another server, it acts as a NAS for
  the remote server. On the remote server, you need to add the hostname of
  your server and the same secret to /etc/raddb/clients.conf as well.

  As you might not control the remote radius server, you might want to
  control the attributes sent back by the remote server in an Access-Accept
  packet. Have a look at the attrs file for this!

4. WHAT HAPPENS

  The exact thing that happens is this:

  - A user logs in with a realm
  - The hints file gets processed as usual
  - The user is checked against the huntgroups file. At this point
    the user _might_ already be rejected.
  - The realm is looked up in the realms file. If it isn't defined,
    the users file is processed normally.
  - If the 'notrealm' option is defined, the user is processed
    locally.
  - The realm is stripped from the username unless "nostrip" was
    set, and the request is sent to a remote radius server. Note that
    any stripping done in the hints file doesn't have an effect on the
    username sent to the remote radius server unless you set the
    "hints" option.
  - The remote server replies with ACK or REJECT

    On ACK:       The initial Auth-Type is set to Accept
    On REJECT:    The initial Auth-Type is set to Reject

    Then the users file is processed as usual. The username used at
    this point is the one after hints file processing (regardless of
    the "hints" option). It also includes the realm (regardless of the
    setting of the "nostrip" option) unless the realm is LOCAL.
