I am not sure but it is possible that all the trouble I see in modern distributions are caused by switch OPENSSL_TLS_SECURITY_LEVEL=2 in OpenSSL lib. I cannot use certificate with weak key (1024 bits is weak now), I cannot connect to clients with TLSv1.0 and TLSv1.1, etc.
$ openssl version -a OpenSSL 1.1.1f 31 Mar 2020 built on: Wed Mar 9 12:12:45 2022 UTC platform: debian-amd64 options: bn(64,64) rc4(16x,int) des(int) blowfish(ptr) compiler: gcc -fPIC -pthread -m64 -Wa,--noexecstack -Wall -Wa,--noexecstack -g -O2 -fdebug-prefix-map=/build/openssl-2iuOVN/openssl-1.1.1f=. -fstack-protector-strong -Wformat -Werror=format-security -DOPENSSL_TLS_SECURITY_LEVEL=2 -DOPENSSL_USE_NODELETE -DL_ENDIAN -DOPENSSL_PIC -DOPENSSL_CPUID_OBJ -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DKECCAK1600_ASM -DRC4_ASM -DMD5_ASM -DAESNI_ASM -DVPAES_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -DX25519_ASM -DPOLY1305_ASM -DNDEBUG -Wdate-time -D_FORTIFY_SOURCE=2 OPENSSLDIR: "/usr/lib/ssl" ENGINESDIR: "/usr/lib/x86_64-linux-gnu/engines-1.1" Seeding source: os-specific This is Ubuntu 18.04, it has no switch OPENSSL_TLS_SECURITY_LEVEL and I had more freedom to experiment with security protocols: $ openssl version -a OpenSSL 1.1.1 11 Sep 2018 built on: Wed Mar 9 12:13:40 2022 UTC platform: debian-amd64 options: bn(64,64) rc4(16x,int) des(int) blowfish(ptr) compiler: gcc -fPIC -pthread -m64 -Wa,--noexecstack -Wall -Wa,--noexecstack -g -O2 -fdebug-prefix-map=/build/openssl-vxXVMf/openssl-1.1.1=. -fstack-protector-strong -Wformat -Werror=format-security -DOPENSSL_USE_NODELETE -DL_ENDIAN -DOPENSSL_PIC -DOPENSSL_CPUID_OBJ -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DKECCAK1600_ASM -DRC4_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -DX25519_ASM -DPADLOCK_ASM -DPOLY1305_ASM -DNDEBUG -Wdate-time -D_FORTIFY_SOURCE=2 OPENSSLDIR: "/usr/lib/ssl" ENGINESDIR: "/usr/lib/x86_64-linux-gnu/engines-1.1" Seeding source: os-specific root@budgie:~# openssl version -a | grep blow options: bn(64,64) rc4(16x,int) des(int) blowfish(ptr) root@budgie:~# openssl version -a | grep LEVEL -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1969859 Title: tlsv1.0 was removed To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/curl/+bug/1969859/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs