Uses lower than default TLS settings

[Dimitri John Ledkov]

Currently freetds is built against gnutls library, but has support for both gnutls & openssl.

It tries to set priority strings, and sets them to lower values that are default in Ubuntu and/or supported by SQL Server.

Please stop directly setting gnutls priority string, or use the same one as is used in gnutls in Ubuntu. NORMAL:-VERS-ALL:+VERS-TLS1.3:+VERS-TLS1.2:+VERS-DTLS1.2:%PROFILE_MEDIUM

Alternatively, please build using openssl library, as that would ensure that security level 2 is enforced without any code changes of freetds. (Built in default is DEFAULT@SECLEVEL=2)

All recent/updated version of SQL Server support TLSv1.2 https://support.microsoft.com/en-gb/help/3135244/tls-1-2-support-for-microsoft-sql-server