EAP fails on TLS protocol version with Windows 7, works fine with Windows 10

[Jochem Sparla]

I have a setup with a Windows 7 and Windows 10 computer authenticating with FreeRADIUS 3.0.20 running on Ubuntu 20.04.

The Windows 7 client fails due to a TLS protocol version error:
(2) eap_peap: TLS_accept: before SSL initialization
(2) eap_peap: <<< recv TLS 1.3  [length 0062]
(2) eap_peap: >>> send TLS 1.0 Alert [length 0002], fatal protocol_version
(2) eap_peap: ERROR: TLS Alert write:fatal:protocol version
tls: TLS_accept: Error in error
(2) eap_peap: ERROR: Failed in __FUNCTION__ (SSL_read): error:14209102:SSL routines:tls_early_post_process_client_hello:unsupported protocol
(2) eap_peap: ERROR: System call (I/O) error (-1)
(2) eap_peap: ERROR: TLS receive handshake failed during operation
(2) eap_peap: ERROR: [eaptls process] = fail
(2) eap: ERROR: Failed continuing EAP PEAP (25) session.  EAP sub-module failed
(2) eap: Sending EAP Failure (code 4) ID 3 length 4
(2) eap: Failed in EAP select
(2)     [eap] = invalid
(2)   } # authenticate = invalid
(2) Failed to authenticate the user
(2) Using Post-Auth-Type Reject


The Windows 10 client, with the same settings on both the client, switch and the same RADIUS server, works fine:
(2) eap_peap: TLS_accept: before SSL initialization
(2) eap_peap: <<< recv TLS 1.3  [length 0097]
(2) eap_peap: TLS_accept: SSLv3/TLS read client hello
(2) eap_peap: >>> send TLS 1.2  [length 003d]
(2) eap_peap: TLS_accept: SSLv3/TLS write server hello
(2) eap_peap: >>> send TLS 1.2  [length 0308]
(2) eap_peap: TLS_accept: SSLv3/TLS write certificate
(2) eap_peap: >>> send TLS 1.2  [length 014d]
(2) eap_peap: TLS_accept: SSLv3/TLS write key exchange
(2) eap_peap: >>> send TLS 1.2  [length 0004]
(2) eap_peap: TLS_accept: SSLv3/TLS write server done
(2) eap_peap: TLS_accept: Need to read more data: SSLv3/TLS write server done
(2) eap_peap: TLS - In Handshake Phase
(2) eap_peap: TLS - got 1194 bytes of data
(2) eap_peap: [eaptls process] = handled
(2) eap: Sending EAP Request (code 1) ID 4 length 1004
(2) eap: EAP session adding &reply:State = 0x30a058ae32a441c4
(2)     [eap] = handled
(2)   } # authenticate = handled
(2) Using Post-Auth-Type Challenge


TLS is configured in mods-enabled/eap:
tls_max_version = "1.2"
tls_min_version = "1.0"


I have been breaking my head and searching this for multiple days.
The problem does not seem to be in the lack of TLS 1.3 support in FreeRADIUS/OpenSSL1.1.1f, because the Win10 client works fine. It starts by asking for TLS 1.3, but gets set to TLS 1.2 and works.
I seems my standard Windows 7 client (fully up to date) sends a bad TLS message, but I have no clue where to look for a solution.


Thanks in advance,  Jochem


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