title: How can I prevent nginx from serving http/2?
body: <p>I am working on implementing http/2 for an ecommerce website my company made. I'm hosting it on debian jessie and found that it's now pretty easy to get nginx from the backports repo which was built against openssl 1.0.2 to support ALPN (which is necessary these days to work with chrome).</p>
  
  <p>So I upgraded my libssl and then my nginx. To my great surprise, nginx now seems to be serving my content through http2 even though I didn't add that keyword to the config. Chrome's dev tools show <code>h2</code> in the <code>protocol</code> column of the network tab.</p>
  
  <p>Normally I would be happy about that, but I'd like to make some comparison measurements between http1.1 and http2. How can I force it to serve http1.1 again (temporarily) to make my measurements?</p>
  
  <p>Edit: adding output of <code>nginx -V</code> to be specific about my version</p>
  
  <pre><code>$ nginx -V
  nginx version: nginx/1.9.10
  built with OpenSSL 1.0.2h  3 May 2016
  TLS SNI support enabled
  configure arguments: --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -D_FORTIFY_SOURCE=2' --with-ld-opt='-fPIE -pie -Wl,-z,relro -Wl,-z,now' --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 --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-ipv6 --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_addition_module --with-http_dav_module --with-http_geoip_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module --with-http_v2_module --with-http_sub_module --with-http_xslt_module --with-stream --with-stream_ssl_module --with-mail --with-mail_ssl_module --with-threads --add-module=/build/nginx-1.9.10/debian/modules/nginx-auth-pam --add-module=/build/nginx-1.9.10/debian/modules/nginx-dav-ext-module --add-module=/build/nginx-1.9.10/debian/modules/nginx-echo --add-module=/build/nginx-1.9.10/debian/modules/nginx-upstream-fair --add-module=/build/nginx-1.9.10/debian/modules/ngx_http_substitutions_filter_module
  </code></pre>