EAP-PEAP-MD5-Challenge

What is Expansion of EAP-PEAP-MD5-Challenge?

EAP-PEAP-MD5-Challenge stands for Extensible Authentication Protocol – Protected Extensible Authentication Protocol – MD5 Challenge.

What is EAP-PEAP-MD5-Challenge?

It is an authentication method where the MD5-Challenge mechanism is used inside a PEAP (Protected EAP) tunnel. The outer PEAP establishes a TLS tunnel, and the inner MD5-Challenge provides password-based authentication.

Why is EAP-PEAP-MD5-Challenge useful?

  • Protects MD5-Challenge by encapsulating it inside a TLS tunnel.

  • Provides a basic password authentication method with additional security.

  • Useful in networks that need simple credential exchange but still want TLS protection.

How it works?

  • The supplicant and server establish a TLS tunnel using PEAP.

  • Inside the tunnel, the server sends an MD5 challenge.

  • The client responds with a hash of the challenge and its password.

  • The server validates this response with stored credentials.

Where is EAP-PEAP-MD5-Challenge used?

  • Enterprise Wi-Fi authentication.

  • VPN authentication via RADIUS.

  • Environments where password-only authentication is acceptable but requires TLS protection.

Which OSI layer does this protocol belong to?

  • Works at the Application Layer (EAP/PEAP).

  • Relies on TLS (presentation/transport security) and uses RADIUS at transport level.

Is EAP-PEAP-MD5-Challenge Windows specific?

  • No. It is supported on Windows but also available on other platforms with supplicant support.

Is EAP-PEAP-MD5-Challenge Linux specific?

  • No. Works on Linux (e.g., wpa_supplicant + FreeRADIUS) and other OSes.

Which Transport Protocol is used by EAP-PEAP-MD5-Challenge?

  • Uses EAP over RADIUS, which typically runs over UDP (1812/1813).

  • TLS tunnel runs inside EAP messages.

Which Port is used by EAP-PEAP-MD5-Challenge?

  • RADIUS authentication: UDP 1812.

  • RADIUS accounting: UDP 1813.

  • (Legacy: 1645/1646).

Is EAP-PEAP-MD5-Challenge using Client-Server model?

  • Yes. - Client (supplicant) ↔ Authenticator (AP/Switch) ↔ Authentication Server (RADIUS).

Whether EAP-PEAP-MD5-Challenge protocol uses certificates?

  • Yes, server certificates are mandatory to set up the TLS tunnel.

  • The MD5 challenge-response happens inside the tunnel.

How many frame exchanges are seen during connection for EAP-PEAP-MD5-Challenge protocol?

  • Initial EAPoL (Start/Identity).

  • TLS handshake messages.

  • MD5-Challenge/Response inside tunnel.

  • Success/Failure.

  • Around 6–10 exchanges, depending on TLS handshake.

Whether EAP-PEAP-MD5-Challenge Protocol uses client certificates?

  • No. Client uses username + password.

  • Only server presents certificate for TLS tunnel.

Whether EAP-PEAP-MD5-Challenge Protocol uses Server Certificates?

  • Yes. Required for TLS tunnel establishment.

Is EAP-PEAP-MD5-Challenge Protocol dependent on TCP?

  • Indirectly – TLS uses TCP when run outside RADIUS, but in Wi-Fi/RADIUS environments it mostly runs over UDP.

Is EAP-PEAP-MD5-Challenge Protocol dependent on UDP?

  • Yes. Typically carried in RADIUS messages over UDP (1812/1813).

What are the roles involved when testing EAP-PEAP-MD5-Challenge Protocol?

  • Supplicant (Client device) – requests authentication.

  • Authenticator (AP/Switch) – forwards EAP messages.

  • Authentication Server (RADIUS) – validates MD5 challenge/response inside TLS tunnel.

Does EAP-PEAP-MD5-Challenge Protocol work with FreeRADIUS server on Linux?

  • Yes. FreeRADIUS supports PEAP with MD5-Challenge as an inner method.

Does EAP-PEAP-MD5-Challenge Protocol work with Internal RADIUS server of hostapd?

  • Hostapd’s built-in RADIUS may have limited support. Usually external FreeRADIUS is used for PEAP-MD5.

What is the RFC version used for EAP-PEAP-MD5-Challenge Protocol?

  • EAP: RFC 3748.

  • MD5-Challenge: RFC 1994.

  • PEAP itself: Internet-Draft (not IETF standardized).

During Connection Procedure which EAPoL packets are encrypted?

  • Outer EAPoL packets (Identity, Start, Success/Failure) are not encrypted.

  • Inner MD5-Challenge/Response is encrypted inside TLS tunnel.

Can you explain different stages of Connection Procedure for EAP-PEAP-MD5-Challenge?

  • Stage 1: EAPoL start/identity exchange.

  • Stage 2: TLS handshake to set up PEAP tunnel.

  • Stage 3: MD5 challenge/response inside TLS tunnel.

  • Stage 4: Server validates response.

  • Stage 5: Authentication Success → PMK derived.

What is the final output of Connection Procedure?

  • A Pairwise Master Key (PMK) is generated for secure communication.

What is the format of the key generated after the connection procedure?

  • PMK is a 256-bit (32-byte) key.

Where is the use of PMK generated by the Connection Procedure?

  • PMK is used in the 4-way handshake to derive PTK.

  • PTK encrypts unicast traffic and secures Wi-Fi communication.

  • In this section, you are going to learn

  • Terminology

  • Version Info

  • rfc details

  • Run Free RADIUS

FreeRADIUS: Download latest freeradius source code

Note

  • Make sure internet is available in laptop to download freeradius package

test:~$ wget https://github.com/FreeRADIUS/freeradius-server/archive/v3.0.x.tar.gz

FreeRADIUS: Extract freeradius

test:~$ tar -zvf v3.0.x.tar.gz

FreeRADIUS: Change directory to Radius server

test:~$ cd freeradius-server-3.0/

FreeRADIUS: Check the current working directory using pwd command

Note

  • Make sure your current working directory is freeradius-server-3.0

test:~$ pwd
/home/test/freeradius-server-3.0

FreeRADIUS: Open debian/rules and add this line –without-rml_sql_iodbc above –without-rlm_eap_ikev2

test:~$ vim debian/rules
--without-rml_sql_iodbc \
--without-rlm_eap_ikev2 \

FreeRADIUS: Configure for Compilation

test:~$ ./configure

FreeRADIUS: Build the Radius server

test:~$ make

FreeRADIUS: Go to raddb folder (all radius server/client files and certificates and keys will be generated here)

test:~$ cd /usr/local/etc/raddb

FreeRADIUS: Open clients.conf file and verify localhost client is present else add your own client like below

test:~$ sudo vi clients.conf

client 192.168.56.10{
ipaddr = 192.168.56.10
secret = testing123
}  

FreeRADIUS: Open users file and uncomment below two lines or add

test:~$ sudo vi users

bob 	Cleartext-Password := "testing123"
 	Reply-Message := "Hello, %{User-Name}"

FreeRADIUS: Set default_eap_type=tls in eap file located in /usr/local/etc/raddb/mods-enabled

test:~$ sudo vi /usr/local/etc/raddb/mods-enabled/eap

default_eap_type=peap

FreeRADIUS: Start radius server

test:~$ sudo radiusd -X
  • Run AP mode operation with hostapd

AP : Download hostapd

Note

  • Make sure internet is available in laptop to download hostapd package

test:~$ wget http://w1.fi/releases/hostapd-2.9.tar.gz

AP: Install required packages

test:~$ sudo apt install libnl-genl-3-dev libnl-3-dev libdbus-glib-1-dev

AP : Extract hostapd

test:~$ tar -xzvf hostapd-2.9.tar.gz

AP : Change directory to hostapd

test:~$ cd hostapd-2.9/hostapd/

AP : Check the current working directory using pwd command

Note

  • Make sure your current working directory is hostapd

test:~$ pwd
/home/test/hostapd-2.9/hostapd

AP : Copy the contents of defconfig file to .config file

Note

  • .config file is required for make to start compilation of hostapd

test:~$ sudo cp defconfig .config

AP : Complile hostapd

Note

  • Compile hostapd by running make command

test:~$ make

AP : Check for the binaries created

Note

  • Make sure hostapd and hostapd_cli are present

test:~$ ls
hostapd
hostapd_cli

AP : Create a hostapd.conf file in /etc/hostapd folder with below content

test:~$ sudo vim /etc/hostapd/hostapd.conf

ctrl_interface=/var/run/hostapd
interface=enp0s8
driver=wired
logger_stdout=1
logger_stdout_level=1
debug=2
ieee8021x=1
eap_server=0
eap_user_file=/etc/hostapd/eap_user
eap_reauth_period=3600
use_pae_group_addr=1
auth_algs=1
auth_server_addr=127.0.0.1
auth_server_port=1812
auth_server_shared_secret=testing123
acct_server_addr=127.0.0.1
acct_server_port=1812
acct_server_shared_secret=testing123
macaddr_acl=0
ca_cert=/usr/local/etc/raddb/certs/ca.pem
server_cert=/usr/local/etc/raddb/certs/server.crt
private_key=/usr/local/etc/raddb/certs/server.p12
private_key_passwd=whatever 

AP : Create a file eap_user in /etc/hostapd/ folder with below content

test:~$ sudo vim /etc/hostapd/eap_user

AP : Run hostapd

test:~$ sudo ./hostapd /etc/hostapd/hostapd.conf
enp0s8: interface state UNINITIALIZED->ENABLED
enp0s8: AP-ENABLED

STA : Download wpa_supplicant

Note

  • Make sure internet is available in laptop to download supplicant package

test:~$ wget https://w1.fi/releases/wpa_supplicant-2.9.tar.gz

STA: Install required packages

test:~$ sudo apt install libnl-genl-3-dev libnl-3-dev libdbus-glib-1-dev

STA : Extract wpa_supplicant

test:~$ tar -xvf wpa_supplicant-2.9.tar.gz

STA : Change directory to wpa_supplicant

test:~$ cd wpa_supplicant-2.9/wpa_supplicant/

STA : Check the current working directory using pwd command

Note

  • Make sure your current working directory is wpa_supplicant

test:~$ pwd
/home/test/wpa_supplicant-2.9/wpa_supplicant

STA : Copy the contents of defconfig file to .config file

Note

  • .config file is required for make to start compilation of supplicant

test:~$ cp defconfig .config

STA : Compile wpa_supplicant

Note

  • Compile supplicant by running make command.

test:~$ make

STA: You might get errors while make regarding openssl headers in that case install the openssl headers and then do make clean and then do make again.

test:~$ sudo apt install libssl-dev
test:~$ make clean
test:~$ make

STA : Check for the binaries created

Note

  • Make sure wpa_supplicant and wpa_cli are present

test:~$ ls
wpa_supplicant
wpa_cli

STA: Copy required certificates from hostapd to wpa_supplicant

STA : Create wpa_supplicant.conf

test:~$ sudo vim wpa_supplicant.conf

ctrl_interface=/run/wpa_supplicant
update_config=1
network={
key_mgmt=WPA-EAP
eap=PEAP
phase2="auth=MD5"
identity="bob"
password="testing123"
}

STA : Run wpa_supplicant

test:~$ sudo ./wpa_supplicant -D wired -i enp0s8 -c wpa_supplicant.conf
enp0s8: CTRL-EVENT-EAP-SUCCESS EAP authentication completed successfully

STA: Test

test:sudo ./wpa_cli -i enp0s8
> status
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