FreeRadius et client XP

FreeRADIUS/WinXP Authentication Setup

This post describes how to build a FreeRADIUS server for TLS and PEAP authentication, and how to configure the Windows XP clients (supplicants). The server is configured for a home (or test) network.

Three papers have been written about TLS authentication with a FreeRADIUS server:

1) www.missl.cs.umd.edu/wireless/eaptls
2) www.freeradius.org/doc/EAPTLS.pdf
3) www.denobula.com

These papers provide an excellent background, but are somewhat out of date. Where appropriate, I will simply refer to these documents rather than repeating the information. I recommend that you follow the steps I give below rather than the steps in these documents.

In the steps below, I give examples from the FreeRADIUS server that I installed yesterday in my Red Hat 9 computer. If you follow this example, please make the needed changes to the names of the files. I installed the FreeRADIUS and OpenSSL files in special local directories. This ensures that there is no interaction between the base Linux files and the new files. It also allows you to easily remove all of the newly installed files.

One word of caution: Be prepared for some frustration. The FreeRADIUS and OpenSSL snapshots used in constructing the server are beta software. Don't be surprised if you encounter some problems.

1. Download and Install OpenSSL and FreeRADIUS

The first step is to download and install the latest snapshot versions of OpenSSL and FreeRADIUS.

a. OpenSSL -- Download the latest OpenSSL-0.9.7-stable snapshot. I downloaded the OpenSSL snapshot to my home directory. The snapshots are located at:

»ftp://ftp.openssl.org/snapshot/

Then I used the following nine steps:

mkdir -p /usr/src/802/openssl
cd /usr/src/802/openssl
cp /home/jbibe/openssl-0.9.7-stable-SNAP-20040202.tar.gz \
openssl-0.9.7-stable-SNAP-20040202.tar.gz

gunzip openssl-0.9.7-stable-SNAP-20040202.tar.gz
tar xvf openssl-0.9.7-stable-SNAP-20040202.tar
cd openssl-0.9.7-stable-SNAP-20040202

./config shared --prefix=/usr/local/openssl
make
make install

That completes the work with OpenSSL, except for building the required certificates.

When you perform the config, make, and make-install here and in the FreeRADIUS install described below, I recommend that you log the information. For example, instead of using the simple "make" command, use:

make > mymake.log 2>&1

If you encounter problems, you can review mymake.log (or myconfig.log, or myinstall.log) for errors.

b. FreeRadius -- Download the latest FreeRADIUS snapshot. Again, I downloaded the file to my home directory. The snapshot is located at:

»ftp://ftp.freeradius.org/pub/radius/CVS-snapshots/

Then I used the following nine steps:

mkdir -p /usr/src/802/radius
cd /usr/src/802/radius
cp /home/jbibe/freeradius-snapshot-20040203.tar.gz \
freeradius-snapshot-20040203.tar.gz

gunzip freeradius-snapshot-20040203.tar.gz
tar xvf freeradius-snapshot-20040203.tar
cd freeradius-snapshot-20040203

./configure --with-openssl-includes=/usr/local/openssl/include \
--with-openssl-libraries=/usr/local/openssl/lib \
--prefix=/usr/local/radius
make
make install

That completes the work with FreeRADIUS, except for building certificates, making the changes to the FreeRADIUS configuration files, moving the server certificates to their final location, and building a wrapper for radiusd.

2. Produce Certificates

Server and client certificates are needed for TLS and PEAP. To produce the required certificates, I recommend that you use CA.all that is included with FreeRADIUS. CA.all uses the configuration information in openssl.cnf.

a. openssl.cnf -- Update openssl.cnf for your configuration. The configuration file is located at:

/usr/local/openssl/ssl

A portion of the information from my openssl.cnf is given below. (The company information is does not describe an actual company located in Brentwood, TN.) Note that the configuration information includes the password "whatever". It is the certificate password.

When CA.all executes, it uses this information three times. The first pass through this information produces the root certificates. If you set up your configuration as shown below, you will be able to accept all of the settings in the first pass. The second pass through this information produces the client certificates. You only need to change the commonName to the client name. In my case, I changed the commonName to jbibe. The third pass through this information produces the server certificates. You only need to change the commonName to the server name. In my case, I changed the commonName to micron.

----- Example -------------------------------------------

...
# req_extensions = v3_req

# The extensions to add to a certificate request

[ req_distinguished_name ]

countryName = Country Name (2 letter code)
countryName_default = US
countryName_min = 2
countryName_max = 2

stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = Tennessee

localityName = Locality Name (eg, city)
localityName_default = Brentwood

0.organizationName = Organization Name (eg, company)
0.organizationName_default = Helava

organizationalUnitName = Organizational Unit Name
organizationalUnitName_default = Engineering

commonName = Common Name (eg, YOUR name)
commonName_max = 64
commonName_default = HAI

emailAddress = Email Address
emailAddress_max = 40
emailAddress_default = ohb@cmcast.net

# SET-ex3 = SET extension number 3

[ req_attributes ]

challengePassword = A challenge password
challengePassword_min = 4
challengePassword_max = 20
challengePassword_default = whatever

unstructuredName = An optional company name

---------------------------------------------------------

b. CA.all -- Update the CA.all script for your requirements. The file is located at:

/usr/src/802/radius/freeradius-snapshot-20040203/scripts

If you use the default password "whatever", you only need to verify that the path in the script points to the installed openssl information. No changes should be necessary, but there is one gotcha. At about line 30, the path will probably be in error. Look for the following line and update the path as needed.

echo "newreq.pem" | /usr/local/openssl/ssl/misc/CA.pl -newca

When CA.all executes, it produces nine certificates:

root.pem, root.p12, root.der
cert-clt.pem, cert-clt.p12, cert-clt.der
cert-srv.pem, cert-srv.p12, cert-srv.der

For TLS and PEAP, the server needs root.pem and cert-srv.pem. For TLS, the Windows XP client needs root.der and cert-clt.p12. For PEAP, the Windows XP client needs root.der.

In the event that you want to use TLS authentication with multiple clients, Document 3 provides the needed script. Look for the CA.clt script in Section 6.

3. Configure Server for TLS

There are only a few changes and additions needed for TLS authentication. The clients.conf, users, and radiusd.conf are located at:

/usr/local/radius/etc/raddb

a. clients.conf -- This file contains the basic configuration for the Access Point. Look for the following line then uncomment and modify as appropriate:

#client 192.168.0.0/24 {

client 192.168.1.0/24 {
secret = AP_Shared_Secret
shortname = WLAN
}

b. users -- This file contains the basic user information. Look for the following line and then add the user name:

#"John Doe" Auth-Type := Local, User-Password == "hello"
#

jbibe

Note that for TLS, you should not include an Auth-Type or a password. The server is able to determine the correct Auth-Type, and a password is not needed because the client uses a client certificate for authentication.

c. radiusd.conf -- This file contains the server configuration information. Look for the following lines and then change the default_eap_type from md5 to tls:

eap {
default_eap_type = md5

Change md5 to tls.

Move down to the following line, and then uncomment and modify the information, as shown below. Note that I placed the server certificates, dh file and random file in a new directory 1x on my system. Modify the path as needed for your server:

#tls {

tls {
private_key_password = whatever
private_key_file = /usr/local/radius/etc/1x/cert-srv.pem
certificate_file = /usr/local/radius/etc/1x/cert-srv.pem
CA_file = /usr/local/radius/etc/1x/root.pem
dh_file = /usr/local/radius/etc/1x/dh
random_file = /usr/local/radius/etc/1x/random
fragment_size = 1024
include_length = yes
}

No other changes are needed in radiusd.conf for TLS.

d. Server Certificates, DH File, and Random File -- I added a new directory 1x in the radius etc directory, and then copied the server certificates (root.pem and cert-srv.pem) into the directory. Finally, I used the following trick to produce dh and random:

date > dh
date > random

If you prefer, use your keyboard to enter some random characters in these files. Or even better, use the OpenSSL tools to produce the random information for these files.

e. Run-Radius -- The only server addition remaining is wrapper for radiusd. I added a new file run-radius in the /usr/local/radius/sbin directory. The script is from Document 3:

----- Wrapper Script ------------------------------------
#!/bin/sh -x

LD_LIBRARY_PATH=/usr/local/openssl/lib
LD_PRELOAD=/usr/local/openssl/lib/libcrypto.so

export LD_LIBRARY_PATH LD_PRELOAD

/usr/local/radius/sbin/radiusd $@
---------------------------------------------------------

After entering and saving the script, make run-radius executable:

chmod u=rwx run-radius

The server is complete.

4. Install Windows XP Certificates and Setup Client for TLS

The Windows XP certificates need to be installed, and client needs to be configured. I recommend that you follow Raymond McKay's example in Document 3, Section 10, XP Client (Supplicant) Setup. When this step is complete, the client is ready.

5. AP Setup

The AP configuration needs to be modified. This is the setup I used with my ZyXEL B-1000v2. (I assume that the B-1000 has been configured previously to use WEP keys and MAC addresses.)

At the wireless 802.1x tab:

Wireless Port Control = Authentication Required
ReAuthentication Timer = 1800 seconds
Idle Timeout = 3600 seconds
Authentication Database = RADIUS only
Dynamic WEP Key Exchange = 128-bit WEP

At the RADIUS tab for authentication:

Active = Yes
Server IP = 192.168.1.10
Port Number = 1812
Shared Secret = AP_Shared_Secret

6. Test TLS

The final step is to test the server. With Windows XP computer off, start the server in the debug mode by entering:

/usr/local/radius/sbin/run-radius -X -A

The server should start, displaying various debug information before it displays:

----- Example --------------------------------------------

Listening on IP address *, ports 1812/udp and 1813/udp, with proxy on 1814/udp.
Ready to process requests

----------------------------------------------------------

If you don't see the message, look through the debug information for errors and missing information. If you see this message, start the Windows XP computer.

When the Windows XP starts, you will see various messages and certificates exchanged between the client and the server. If all is well, you should see the client authenticated and the user logged on. The following partial example is from Document 3. It shows the last few lines of a successful authentication:

----- Example ---------------------------------------------
...
MS-MPPE-Recv-Key = 0xe032765ca06c052e5fe7c2a7534a4252daec44a08505bdb459d4
fa81e70390f2221d2b06071eb0625e0ba67452a890909662
MS-MPPE-Send-Key = 0xe03131ce085bc266127528e749bd4753d3e1702df2d4d8c080351
380f52eae2c24a9fa78015c24e0d140bcd01b23d6c0cacc
EAP-Message = "\003_\000\004"
Message-Authenticator = 0x00000000000000000000000000000000
Finished request 5
Going to the next request
-----------------------------------------------------------

If you see MS-MPPE-Recv-Key and MS-MPPE-Send-Key, the server authenticated the client. You should be able to surf.

7. Change Server Configuration for PEAP

To change the server for PEAP authentication, only a few changes need to be made.

a. users -- Return to the users file and add the user password:

jbibe User-Password == "My-XP-Password"

b. Radiusd.conf -- Return to the radiusd.conf file and make the following changes:

Change the default_eap_type from tls to peap:

eap {
default_eap_type = peap

Move to the PEAP section below the TLS section and uncomment the following lines:

peap {
default_eap_type = mschapv2
}

The server is now ready for PEAP authentication.

8. Change Windows XP for PEAP

On the Wireless Network tab, select the network and click Configure to open the network properties. Then

Select the Authentication tab
Select Protected EAP on the drop-down list
Click Properties
Enable "Validate server certificate"
In Trusted Root Certification Authorities list, enable the root.der certificate.
In Select Authentication Method, select "Secured password (EAP-MSCHAPv2)"
Click Configure
If desired, enable "Automatically use my Windows logon name and password".

I did not enable "Automatically use my Windows ..." In my HP laptop, the software adds HP\\ before the user name; e.g., HP\\jbibe. If you don't enable this option, windows will ask for your user name and password the first time the laptop tries to connect to the network. The computer will then use the user name and password exactly as entered.

On the original Authentication screen, I disabled the "Authenticate as computer when computer information is available"

Windows XP is now ready for testing.

9. Test PEAP

The final step is to test the server. With Windows XP computer off, start the server in the debug mode by entering:

/usr/local/radius/sbin/run-radius -X -A

The server should start, displaying various debug information. If it displays "Ready to process requests", the server is running. This message is identical to the TLS start message. If you review the debug information, you will see additional messages as peap and mschapv2 start.

If you see the Ready message, start the Windows XP computer. As the client and server communicate, you will see various messages exchanged. If all is well, you should see the client authenticated and the user logged on. Again you will see the MS-MPPE-Recv-Key and the MS-MPPE-Send-Key.

If you review the debug messages, you will see the TLS tunnel being built. Once it is built, you will see verification that messages are passing through the tunnel. Finally, you will see the user authenticated.