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openssldebianfreeswitch

Is openssl wrongly rejecting this session request?

I have OpenSSL 1.1.1n on a Debian11 server, configured to use MinProtocol = TLSv1.2

When the server receives a ClientHello as below:

TLSv1.2 Record Layer: Handshake Protocol: Client Hello
    Content Type: Handshake (22)
    Version: TLS 1.0 (0x0301)
    Length: 142
    Handshake Protocol: Client Hello
        Handshake Type: Client Hello (1)
        Length: 138
        Version: TLS 1.2 (0x0303)

with Record Layer Version set to TLSv.1 but with Handshake Version set to TLSv1.2 it rejects it with a Protocol Version alert and closes the connection, when according to https://datatracker.ietf.org/doc/html/rfc5246#appendix-E this looks like an accepted behavior and should not be rejected.

Is openssl breaching the RFC here, or am I missing a configuration parameter that I can adjust to fix this?

On the other hand, when I decrease the MinProtocol to TLSv1, the server accepts the ClientHello and responds with a TLSv1 Handshake, which causes the entire session to be over TLSv1 and is not accepted by the other party.

Solution

  • I have found out that setting both MinProtocol and MaxProtocol as below:

    MinProtocol = TLSv1
MaxProtocol = TLSv1.2

    fixes the both issues.