In this paper, I describe what a RADIUS server does, the steps I followed in setting it up, how I used the server once it was in place, and some projects for making RADIUS useful in a business context.
Authentication is the process of determining the identity of a user. The most common form of authentication is by user name and password. This is the form used here. Other forms use digital certificates, digital signatures, etc.
Authorization is the process of determining which service(s) a user is permitted to use and to what extent. It requires that the identity of the user be previously established by some authentication process. The authenticated user ID is then authorized by lookup in a file, table, database, or directory service such as LDAP.
Accounting is the process of keeping track of network usage. It records the date and time of the start of each user's session, its duration and the number of bytes transferred.
These are the fundamental elements of the RADIUS service. Additional terminology is defined in my glossary of WiFi terms (http://www.wifi-italy.com/glossary.html).
The sequence of events in the lifecycle of a RADIUS-mediated WiFi connection is:
There are several implementations of the server side of the RADIUS protocol, including:
On the client side of the protocol are a variety of devices called network access servers (NAS). A NAS is a piece of equipment that directly accepts users' connections. For example, in a wireless network the access point (the transmitter/receiver to which the customers connect from their laptops as they eat their burgers) serves as the NAS. In an ISP's dialup network, the NAS is the switch that connects the receiving modems to the computers providing the dialup services (e.g. e-mail and web browsing.)
RADIUS is a standardized protocol. As with other Internet-related protocols, the standard is established by the Internet Engineering Task Force (IETF) and documented in a document termed a Request for Comments (RFC). Specifically, RADIUS is documented in:
One essential detail of the RADIUS specification is that it uses port 1812. Port numbers are part of the TCP/IP mechanism for connecting clients and servers on the Internet. Unless the default is overridden, the FreeRadius server gets the port number by lookup in the /etc/services file, the standard place in Unix (and Linux, Solaris, etc.) where port numbers are kept.
ftp://ftp.freeradius.org/pub/radius/freeradius-0.9.3.tar.gz
C:\> ftp www.wifi-california.com
# gunzip freeradius-0.9.3.tar.gz
# ./configure
# make
# make install
# /usr/local/sbin/radiusd -XThis mode yields voluminous output -- see Appendix 2. It shows where logs and libraries are kept, whether there were any errors parsing the configuration files, etc.
kill -9 `ps -A | grep radiusd | gawk '{ print $1 }'`
# /usr/local/sbin/radiusd
Sat Apr 24 21:32:52 2004 : Info: Starting - reading configuration files ...
# radtest test test localhost 0 testing123
Sending Access-Request of id 138 to 127.0.0.1:1812
User-Name = "test"
User-Password = "test"
NAS-IP-Address = www.dan-keller.com
NAS-Port = 0
Re-sending Access-Request of id 138 to 127.0.0.1:1812
User-Name = "test"
User-Password = " \276\373\034X\352V\203\363\316\020\3066\021\211\352"
NAS-IP-Address = www.dan-keller.com
NAS-Port = 0
rad_recv: Access-Reject packet from host 127.0.0.1:1812, id=138, length=20
client 66.167.77.6 {
secret = laraine
shortname = keller.com
}
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Values to enter into the form:
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Conclusion: All these things will be done. More time is needed.
RADIUSD(8) FreeRADIUS Daemon RADIUSD(8)
NAME
radiusd - Authentication, Authorization and Accounting
server
SYNOPSIS
radiusd [-A] [-S] [-a accounting_directory] [-b] [-c] [-d
config_directory] [-f] [-i ip-address] [-l log_directory]
[-g facility] [-p port] [-s] [-v] [-x] [-X] [-y] [-z]
DESCRIPTION
This is the FreeRADIUS implementation of the well known
radius server program. Even though this program is
largely compatible with Livingston's radius version 2.0,
it's not based on any part of that code.
RADIUS is a protocol spoken between an access server, typ
ically a device connected to several modems or ISDN lines,
and a radius server. When a user connects to the access
server, (s)he is asked for a loginname and a password.
This information is then sent to the radius server. The
server replies with "access denied", or "access OK". In
the latter case login information is sent along, such as
the IP address in the case of a PPP connection.
The access server also sends login and logout records to
the radius server so accounting can be done. These records
are kept for each terminal server seperately in a file
called detail, and in the wtmp compatible logfile
/var/log/radwtmp.
OPTIONS
-A Write a file detail.auth in addition to the stan
dard detail file in the same directory. This file
will contain all the authentication-request
records. This can be useful for debugging, but not
for normal operation.
-S Write the stripped usernames (without prefix or
suffix) in the detail file instead of the raw
record as received from the terminal server.
This command line option is deprecated. See the
log_stripped_names configuration item in the
radiusd.conf file.
-a accounting directory
This defaults to /var/log/radacct. If that direc
tory exists, radiusd will write an ascii accounting
record into a detail file for every login/logout
recorded. The location of the detail file is
acct_dir/terminal_server/detail.
This command line option is deprecated. See the
radacctdir configuration item in the radiusd.conf
file.
-l logging directory
This defaults to /var/log. Radiusd writes a logfile
here called radius.log. It contains informational
and error messages, and optionally a record of
every login attempt (for aiding an ISP's helpdesk).
The special arguments stdout and stderr cause the
information to get written to the standard output,
or standard error instead. The special argument
syslog sends the information with syslog(3).
This command line option is deprecated. See the
log_dir configuration item in the radiusd.conf
file.
-g facility
Specifies the syslog facility to be used with -l
syslog. Default is daemon. Another reasonable
choice would be authpriv.
-d config directory
Defaults to /etc/raddb. Radiusd looks here for its
configuration files such as the dictionary and the
users files.
-i ip-address
Defines which IP addres to bind to for sending and
receiving packets- useful for multi-homed hosts.
This command line option is deprecated. See the
bind_address configuration item in the radiusd.conf
file.
-b If the radius server binary was compiled with dbm
support, this flag tells it to actually use the
database files instead of the flat users file.
This command line option is deprecated, and does
not do anything.
-c This is still an experimental feature. Cache the
password, group and shadow files in a hash-table in
memory. This makes the radius process use a bit
more memory, but username lookups in the password
file are much faster.
After every change in the real password file (user
added, password changed) you need to send a SIGHUP
to the radius server to let it re-read its configu
ration and the password/group/shadow files !
This command line option is deprecated. See the
cache configuration item for the unix module in the
radiusd.conf file.
-f Do not fork, stay running as a foreground process.
-p port
Normally radiusd listens on the ports specified in
/etc/services (radius and radacct). With this
option radiusd listens on the specified port for
authentication requests and on the specified port
+1 for accounting requests.
This command line option is deprecated. See the
port configuration item in the radiusd.conf file.
-s Normally, the server forks a seperate process for
accounting, and a seperate process for every
authentication request. With this flag the server
will not do that. It won't even "daemonize" (auto-
background) itself.
-x Debug mode. In this mode the server will print
details of every request on it's stderr output.
Most useful in combination with -s. You can spec
ify this option 2 times (-x -x or -xx) to get a bit
more debugging output.
-X Extended debug mode. Equivalent to -sfxx, but sim
pler to explain.
-y Write details about every authentication request in
the radius.log file.
This command line option is deprecated. See the
log_auth configuration item in the radiusd.conf
file.
-z Include the password in the radius.log file even
for successful logins. This is very insecure!.
This command line option is deprecated. See the
log_auth_badpass and the log_auth_goodpass configu
ration items in the radiusd.conf file.
CONFIGURATION
Radiusd uses a number of configuration files. Each file
has it's own manpage describing the format of the file.
These files are:
radiusd.conf
The main configuration file, which sets the admin
istrator-controlled items.
dictionary
This file is usually static. It defines all the
possible RADIUS attributes used in the other con
figuration files. You don't have to modify it. It
includes other dictionary files in the same direc
tory.
clients
[ Deprecated ] Contains the IP address and a secret
key for every client that wants to connect to the
server.
naslist
Contains an entry for every NAS (Network Access
Server) in the network. This is not the same as a
client, especially if you have radius proxy server
in your network. In that case, the proxy server is
the client and it sends requests for different
NASes.
It also contains a abbreviated name for each termi
nal server, used to create the directory name where
the detail file is written, and used for the
/var/log/radwtmp file. Finally it also defines what
type of NAS (Cisco, Livingston, Portslave) the NAS
is.
hints Defines certain hints to the radius server based on
the users's loginname or other attributes sent by
the access server. It also provides for mapping
user names (such as Pusername -> username). This
provides the functionality that the Livingston 2.0
server has as "Prefix" and "Suffix" support in the
users file, but is more general. Ofcourse the Liv
ingston way of doing things is also supported, and
you can even use both at the same time (within cer
tain limits).
huntgroups
Defines the huntgroups that you have, and makes it
possible to restrict access to certain huntgroups
to certain (groups of) users.
users Here the users are defined. On a typical setup,
this file mainly contains DEFAULT entries to pro
cess the different types of logins, based on hints
from the hints file. Authentication is then based
on the contents of the UNIX /etc/passwd file. How
ever it is also possible to define all users, and
their passwords, in this file.
SEE ALSO
radiusd.conf(5), users(5), huntgroups(5), hints(5),
clients(5), dictionary(5).
AUTHOR
Miquel van Smoorenburg, miquels@cistron.nl, and others.
23 June 2003 RADIUSD(8)
Starting - reading configuration files ...
reread_config: reading radiusd.conf
Config: including file: /usr/local/etc/raddb/proxy.conf
Config: including file: /usr/local/etc/raddb/clients.conf
Config: including file: /usr/local/etc/raddb/snmp.conf
Config: including file: /usr/local/etc/raddb/sql.conf
main: prefix = "/usr/local"
main: localstatedir = "/usr/local/var"
main: logdir = "/usr/local/var/log/radius"
main: libdir = "/usr/local/lib"
main: radacctdir = "/usr/local/var/log/radius/radacct"
main: hostname_lookups = no
main: snmp = no
main: max_request_time = 30
main: cleanup_delay = 5
main: max_requests = 1024
main: delete_blocked_requests = 0
main: port = 0
main: allow_core_dumps = no
main: log_stripped_names = no
main: log_file = "/usr/local/var/log/radius/radius.log"
main: log_auth = no
main: log_auth_badpass = no
main: log_auth_goodpass = no
main: pidfile = "/usr/local/var/run/radiusd/radiusd.pid"
main: user = "(null)"
main: group = "(null)"
main: usercollide = no
main: lower_user = "no"
main: lower_pass = "no"
main: nospace_user = "no"
main: nospace_pass = "no"
main: checkrad = "/usr/local/sbin/checkrad"
main: proxy_requests = yes
proxy: retry_delay = 5
proxy: retry_count = 3
proxy: synchronous = no
proxy: default_fallback = yes
proxy: dead_time = 120
proxy: post_proxy_authorize = yes
proxy: wake_all_if_all_dead = no
security: max_attributes = 200
security: reject_delay = 1
security: status_server = no
main: debug_level = 0
read_config_files: reading dictionary
read_config_files: reading naslist
Using deprecated naslist file. Support for this will go away soon.
read_config_files: reading clients
Using deprecated clients file. Support for this will go away soon.
read_config_files: reading realms
Using deprecated realms file. Support for this will go away soon.
radiusd: entering modules setup
Module: Library search path is /usr/local/lib
Module: Loaded expr
Module: Instantiated expr (expr)
Module: Loaded PAP
pap: encryption_scheme = "crypt"
Module: Instantiated pap (pap)
Module: Loaded CHAP
Module: Instantiated chap (chap)
Module: Loaded MS-CHAP
mschap: use_mppe = yes
mschap: require_encryption = no
mschap: require_strong = no
mschap: passwd = "(null)"
mschap: authtype = "MS-CHAP"
Module: Instantiated mschap (mschap)
Module: Loaded System
unix: cache = no
unix: passwd = "(null)"
unix: shadow = "(null)"
unix: group = "(null)"
unix: radwtmp = "/usr/local/var/log/radius/radwtmp"
unix: usegroup = no
unix: cache_reload = 600
Module: Instantiated unix (unix)
Module: Loaded eap
eap: default_eap_type = "md5"
eap: timer_expire = 60
rlm_eap: Loaded and initialized the type md5
rlm_eap: Loaded and initialized the type leap
Module: Instantiated eap (eap)
Module: Loaded preprocess
preprocess: huntgroups = "/usr/local/etc/raddb/huntgroups"
preprocess: hints = "/usr/local/etc/raddb/hints"
preprocess: with_ascend_hack = no
preprocess: ascend_channels_per_line = 23
preprocess: with_ntdomain_hack = no
preprocess: with_specialix_jetstream_hack = no
preprocess: with_cisco_vsa_hack = no
Module: Instantiated preprocess (preprocess)
Module: Loaded realm
realm: format = "suffix"
realm: delimiter = "@"
Module: Instantiated realm (suffix)
Module: Loaded files
files: usersfile = "/usr/local/etc/raddb/users"
files: acctusersfile = "/usr/local/etc/raddb/acct_users"
files: preproxy_usersfile = "/usr/local/etc/raddb/preproxy_users"
files: compat = "no"
Module: Instantiated files (files)
Module: Loaded Acct-Unique-Session-Id
acct_unique: key = "User-Name, Acct-Session-Id, NAS-IP-Address, Client-IP-Address, NAS-Port-Id"
Module: Instantiated acct_unique (acct_unique)
Module: Loaded detail
detail: detailfile = "/usr/local/var/log/radius/radacct/%{Client-IP-Address}/detail-%Y%m%d"
detail: detailperm = 384
detail: dirperm = 493
detail: locking = no
Module: Instantiated detail (detail)
Module: Loaded radutmp
radutmp: filename = "/usr/local/var/log/radius/radutmp"
radutmp: username = "%{User-Name}"
radutmp: case_sensitive = yes
radutmp: check_with_nas = yes
radutmp: perm = 384
radutmp: callerid = yes
Module: Instantiated radutmp (radutmp)
Listening on IP address *, ports 1812/udp and 1813/udp, with proxy on 1814/udp.
Ready to process requests.