> On 12 Sep 2017, at 07:29, Brian <crazibri@gmail.com> wrote:
>
> I have the following file named test.stream which is being included via nginx.conf stream { include /etc/nginx/conf.d/*.stream; }
>
> the ssl_preread_server_name variable is not being extracted and I’m running Nginx/1.13.5 (via centos 7 nginx repo). Any idea whats going on here? tcpdump shows the SNI field.
>
> nginx -V
> nginx version: nginx/1.13.5
> built by gcc 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC)
> built with OpenSSL 1.0.1e-fips 11 Feb 2013
> TLS SNI support enabled
>
>
> map $ssl_preread_server_name $name {
> cm.example.com cm;
> ut.example.com ut;
> }
> upstream ut {
> server 10.0.0.76:9000;
> }
> upstream cm {
> server 10.0.0.61:9000;
> }
>
> log_format stream_routing '$remote_addr [$time_local] '
> 'with SNI name "$ssl_preread_server_name" '
> 'proxying to "$name" '
> '$protocol $status $bytes_sent $bytes_received '
> '$session_time';
>
> server {
> listen 443 ssl;
>
> #Certificate & Key .PEM Format
> ssl_certificate /etc/ssl/certs/internal_back.crt;
> ssl_certificate_key /etc/ssl/certs/internal_back.key;
> #CIPHERS
> include /etc/nginx/conf.d/tcp.common;
>
> proxy_pass $name;
> ssl_preread on;
> access_log /var/log/nginx/stream.log stream_routing;
> error_log /var/log/nginx/stream-error.log debug;
> }
>
>

This is not going to work.
ssl_preread isn't designed to work with SSL-terminated connection,
as shown in your snippet, i.e. it won't work with “listen .. ssl”,
since it would parse SSL/TLS Application Data, but not Client Hello.

See for details:
https://nginx.org/en/docs/stream/ngx_stream_ssl_preread_module.html

OTOH, once SSL is terminated, you may use $ssl_server_name variable:
http://nginx.org/en/docs/http/ngx_http_ssl_module.html#var_ssl_server_name

You could also exclude map{} by using $ssl_server_name in proxy_pass.

: upstream cm.example.com {
: server 10.0.0.61:9000;
: }
: upstream ut.example.com {
: server 10.0.0.76:9000;
: }

: server {
: listen 443 ssl;
:
: proxy_pass $ssl_server_name;
: }

The above simplification works with $ssl_preread_server_name as well:

: upstream cm.example.com {
: server 10.0.0.61:9000;
: }
: upstream ut.example.com {
: server 10.0.0.76:9000;
: }

: server {
: listen 443;
:
: proxy_pass $ssl_preread_server_name;
: }

OTOH, you may still want map{} to provide a default value,
if client didn’t sent SNI, or something, e.g.:

: map $ssl_preread_server_name $name {
: “” default.fallback.value;
: default $ssl_preread_server_name;
: }


--
Sergey Kandaurov

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