EAP-TTLS-MSCHAP

What is Expansion of EAP-TTLS-MSCHAP?

Extensible Authentication Protocol - Tunneled Transport Layer Security - Microsoft Challenge Handshake Authentication Protocol.

What is EAP-TTLS-MSCHAP?

EAP-TTLS-MSCHAP is an EAP authentication method where a secure TLS tunnel is established (EAP-TTLS), inside which the MSCHAP (Microsoft Challenge Handshake Authentication Protocol) is used for authenticating the client with username and password.

Why is EAP-TTLS-MSCHAP useful?

  • Protects user credentials by tunneling authentication inside a TLS encrypted channel.

  • Supports legacy password-based authentication protocols like MSCHAP within a secure tunnel.

  • Provides better security than plain MSCHAP by preventing credential sniffing.

How it works?

  1. The client and authentication server establish a TLS tunnel using EAP-TTLS (server authenticates with certificate).

  2. Inside this encrypted tunnel, the client responds to MSCHAP challenge messages with hashed password responses.

  3. The server verifies the MSCHAP response and grants or denies access.

Where is EAP-TTLS-MSCHAP used?

  • Enterprise wireless and wired networks requiring secure password-based authentication.

  • Environments where legacy MSCHAP authentication needs protection with TLS.

  • VPNs and other remote access solutions requiring tunneled authentication.

Which OSI layer does this protocol belong to?

  • Application Layer (Layer 7).

Is EAP-TTLS-MSCHAP windows specific?

  • No, but MSCHAP is a Microsoft-developed protocol and best supported on Windows.

Is EAP-TTLS-MSCHAP Linux Specific?

  • No, supported by Linux supplicants like wpa_supplicant with proper configuration.

Which Transport Protocol is used by EAP-TTLS-MSCHAP?

  • EAPOL for communication between supplicant and authenticator.

  • RADIUS protocol over UDP between authenticator and authentication server.

Which Port is used by EAP-TTLS-MSCHAP?

  • UDP port 1812 (default port for RADIUS Authentication).

Is EAP-TTLS-MSCHAP using Client server model?

  • Yes, involving client (supplicant), authenticator (AP or switch), and authentication server.

Whether EAP-TTLS-MSCHAP protocol uses certificates?

  • Yes, server certificates are used to establish the TLS tunnel.

  • Client certificates are generally not required for MSCHAP inside the tunnel.

How many frame exchanges are seen during connection for EAP-TTLS-MSCHAP protocol?

  • Several exchanges for TLS tunnel establishment plus MSCHAP challenge-response frames inside.

  • Typically around 20-30 EAPOL frame exchanges.

Whether EAP-TTLS-MSCHAP Protocol uses client certificates?

  • Usually no, client authentication is done via MSCHAP username/password.

Whether EAP-TTLS-MSCHAP Protocol uses Server Certificates?

  • Yes, to authenticate the server during TLS tunnel setup.

Is EAP-TTLS-MSCHAP Protocol depends on TCP?

  • Not directly; EAP is a layer 2 protocol using EAPOL.

  • TLS handshake is inside EAP messages.

  • RADIUS communicates over UDP.

Is EAP-TTLS-MSCHAP Protocol depends on UDP?

  • Yes, RADIUS communication occurs over UDP (port 1812).

What are the roles involved when testing EAP-TTLS-MSCHAP Protocol?

  • Client/Supplicant with MSCHAP credentials.

  • Access Point or Network Access Server (Authenticator).

  • Authentication Server (e.g., FreeRADIUS) configured with MSCHAP support.

  • Certificate Authority (CA) for server certificate.

  • Tools like Wireshark for packet capture.

Does EAP-TTLS-MSCHAP Protocol work with free radius server on Linux?

  • Yes, FreeRADIUS supports EAP-TTLS with MSCHAP inside the tunnel.

Does EAP-TTLS-MSCHAP Protocol work with Internal radius server of hostapd?

  • Hostapd’s internal RADIUS server has limited EAP-TTLS support; external RADIUS is preferred.

What is the RFC version use for EAP-TTLS-MSCHAP Protocol?

  • EAP-TTLS is defined in RFC 5281.

  • MSCHAP is a Microsoft proprietary protocol, but documented in RFC 2759.

During Connection Procedure which EPoL Packets are encrypted?

  • All MSCHAP authentication packets inside the TLS tunnel are encrypted.

  • The outer TLS handshake packets are unencrypted until the tunnel is established.

Can you Explain different stages of Connection Procedure for EAP-TTLS-MSCHAP Protocol?

  1. TLS tunnel establishment via EAP-TTLS with server certificate verification.

  2. Inside the tunnel, MSCHAP challenge-response authentication takes place.

  3. Upon successful MSCHAP authentication, PMK is derived.

  4. The client and AP perform the 4-way handshake with the PMK.

  5. Secure wireless communication is established.

What is the final output of Connection Procedure?

  • Successful authentication and derivation of the Pairwise Master Key (PMK).

  • Secure wireless session establishment.

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

  • A 256-bit Pairwise Master Key (PMK).

Where the use of PMK generated by the Connection Procedure?

  • The PMK is used in the 4-way handshake to generate temporal session keys (PTK) for encrypting the wireless data between client and access point.

  • 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=ttls

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=TTLS
phase2="auth=MSCHAP"
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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