TLS1.3

[KvanSteijn@…]

I am completely confuse about TLS 1.3. I have a server running on Debian 9 (stretch) with Nginx-full (nginx/1.14.1) package. This package comes from Debian repo. With this package TLS1.3 is woking good and have no any known issues.

I setup separated server with Debian 9 (stretch) and install Nginx (nginx/1.18.0) directly from your repo and after the installation TLS 1.3 is not working anymore. No errors by starting and running Nginx with TLS1.3 enabled in ssl_procotols, but the browser doesn't start an TLS1.3 connection. When I install the old version Nginx-full (nginx/1.14.1) then TLS1.3 is working as expected.

On both server is installed a newer version of openSSL, courtesy of deb.sury.org

Nginx-full:
uname -a: Linux manager2 4.9.0-14-amd64 #1 SMP Debian 4.9.246-2 (2020-12-17) x86_64 GNU/Linux

nginx version: nginx/1.14.1
built with OpenSSL 1.1.0f 25 May 2017 (running with OpenSSL 1.1.1i 8 Dec 2020)
TLS SNI support enabled
configure arguments: --with-cc-opt='-g -O2 -fdebug-prefix-map=/build/nginx-jqo7Nx/nginx-1.14.1=. -fstack-protector-strong -Wformat -Werror=format-security -fPIC -Wdate-time -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -fPIC' --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --modules-path=/usr/lib/nginx/modules --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_v2_module --with-http_dav_module --with-http_slice_module --with-threads --with-http_addition_module --with-http_geoip_module=dynamic --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module=dynamic --with-http_sub_module --with-http_xslt_module=dynamic --with-stream=dynamic --with-stream_ssl_module --with-stream_ssl_preread_module --with-mail=dynamic --with-mail_ssl_module --add-dynamic-module=/build/nginx-jqo7Nx/nginx-1.14.1/debian/modules/http-auth-pam --add-dynamic-module=/build/nginx-jqo7Nx/nginx-1.14.1/debian/modules/http-dav-ext --add-dynamic-module=/build/nginx-jqo7Nx/nginx-1.14.1/debian/modules/http-echo --add-dynamic-module=/build/nginx-jqo7Nx/nginx-1.14.1/debian/modules/http-upstream-fair --add-dynamic-module=/build/nginx-jqo7Nx/nginx-1.14.1/debian/modules/http-subs-filter

[Maxim Dounin]

nginx version: nginx/1.14.1
built with OpenSSL 1.1.0f 25 May 2017 (running with OpenSSL 1.1.1i 8 Dec 2020)

This version of nginx, 1.14.1, is several years old and lacks the following bugfix introduced in ​nginx 1.15.6:

    *) Bugfix: if nginx was built with OpenSSL 1.1.0 and used with OpenSSL
       1.1.1, the TLS 1.3 protocol was always enabled.

As such, in such a configuration TLS 1.3 was always enabled and it was not possible to disable it, see ticket #1654.

With newer nginx versions such a configuration (nginx built with OpenSSL 1.1.0, yet running with OpenSSL 1.1.1) will result in TLS 1.3 being not available. For TLS 1.3 to work, you have to recompile nginx with OpenSSL 1.1.1. If you want to use TLS 1.3 and don't want to recompile nginx yourself, consider upgrading to Debian 10 (buster).