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FreeRADIUS is a very versatile and freely available RADIUS server under the GPL license. Setting up FreeRADIUS as an SP is a rather straightforward task, since it merely needs to forward requests from NASes to other RADIUS servers. In particular, it does not need to authenticate users. The following configuration enables your FreeRADIUS server to be an eduroam SP. At the same time, it is the baseline from which to establish an eduroam IdP configuration, if that is envisaged for a later stage.

Version information

This documentation is current as of FreeRADIUS 2.1.10.

Installation

FreeRADIUS is written in C and can be compiled with the usual UNIX compilation sequence. After unpacking the source into a directory of your choice, do

./configure --prefix=<your preferred install dir> --sysconfdir=<your preferred configuration base dir>
make
make install

In the examples below, we assume the installation is done for --prefix=/usr/local/freeradius/ and the configuration dir is --sysconfdir=/etc

Sample config directory

Base configuration / logging / F-Ticks

The main configuration file is /etc/radiusd.conf; it does not require many changes from the shipped default. That's because the logic in the server is done by activating certain modules in a certain order. These modules are separately defined and configured in the /etc/modules/ subdirectory. The order of activation of these modules is defined in so-called virtual servers, which are defined in the /etc/sites-enabled/ directory. For our eduroam SP purposes, we only need one virtual server "eduroam". It needs to contain as a minimum:

 server eduroam {

        authorize {
                auth_log
                suffix
        }

        authenticate {
        }

        preacct {
                suffix
        }

        accounting {
        }

        post-auth {
                reply_log
                Post-Auth-Type REJECT {
                        reply_log
                }
        }

        pre-proxy {
                pre_proxy_log
                if (Packet-Type != Accounting-Request) {
                        attr_filter.pre-proxy
                }
        }

        post-proxy {
                post_proxy_log
                attr_filter.post-proxy        }
}

The multitude of sections in this above configuration is often confusing to new-comers. The order of execution when proxying a request are:

authorize → authenticate → pre-proxy

Then, the packet is proxied to an upstream server. When the reply comes back, the execution continues:

post-proxy → post-auth

Every stanza contains names of modules to be executed. Let's revisit them one after another:

  • auth_log: logs the incoming packet to the file system. This is needed to fulfull the eduroam SP logging requirements.
  • suffix: inspects the packet to look for an eduroam style realm (separated by the @ sign)
  • pre_proxy_log: logs the packet to the file system again. Attributes that were added during the inspection process before are then visible to the administrator - great for debugging
  • attr_filter.pre-proxy: strips unwanted attributes off of the request before sending the request to upstream
  • post_proxy_log: logs the reply packet to the file system - as received by upstream
  • attr_filter.post-proxy: strips unwanted attributes off of the reply, prior to sending it back to the Access Points (VLAN attributes in particular!)
  • reply_log: logs the reply packet after attribute filtering to the file system

The paths where the logs are written to, and the files with the list of permitted attributes for filtering, are defined in the corresponding module definitions in /etc/modules/<name-of-module>.

Client definition

FreeRADIUS defines the connected RADIUS clients in the file /etc/raddb/clients.conf. This file needs to hold all your connected Access Points and/or wired eduroam-enabled switches. You set a shared secret for each client and define these in the config file as follows:

 client antarctica-access-point-1 {
    ipaddr         = 172.25.1.55
    netmask        = 32
    secret         = yoursecret12345
    shortname      = southpole-11g
    virtual_server = eduroam
}

There are more (optional) settings for clients; please consult the comments in clients.conf for more detail. One option, the "virtual_server" one, enables your RADIUS server to serve more purposes than only eduroam: you can define several other virtual servers for other RADIUS purposes, and link clients to these. That is beyond the scope of this documentation, though.

If you want to connect your clients over IPv6, the syntax is only slightly different:

 client antarctica-access-point-2 {    ipv6addr       = 2001:db8:1:789::56
    netmask        = 128
    secret         = yoursecretABCDE
    shortname      = southpole-11n
    virtual_server = eduroam
}

Request forwarding

FreeRADIUS contains a wealth of options to define how requests are forwarded. These options are defined in the file /etc/proxy.conf. For a single eduroam SP, these may seem overkill, but the required definitions for that purpose are rather static. Assuming you have two upstream servers to forward requests to, the following configuration will set these up - you only need to change the IP addresses and shared secrets in home_server stanzas.

proxy server {
        default_fallback        = yes
}

home_server antarctica-flr-1 {
        type                    = auth+acct
        ipaddr                  = 172.20.1.2
        port                    = 1812
        secret                  = secretstuff
        status_check            = status-server
}

home_server antarctica-flr-2 {
        type                    = auth+acct
        ipv6addr                = 172.25.9.3
        port                    = 1812
        secret                  = secretstuff
        status_check            = status-server
}

home_server_pool EDUROAM {
        type                    = fail-over
        home_server             = antarctica-flr-1
        home_server             = antarctica-flr-2
}

realm DEFAULT {
        pool                    = EDUROAM
        nostrip
}

Goodies

Caveats

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