Why can't I use the "ssl" modified on more than one listen statement?

[Maxim Dounin]

Hello!

On Tue, Sep 21, 2010 at 11:39:46AM -0400, portante wrote:

> Hi,
> 
> The following is an example of how we would like to run our
> configuration.
> 
> [code]
> ssl_certificate      common.crt;
> ssl_certificate_key  common.key;
>  
> server {
>   listen           80;
>   server_name      www.nginx.org;
>   ...
> }
>  
> server {
>   listen           443 default ssl;
>   server_name      secure.nginx.org;
>   ...
> }
>  
> server {
>   listen           80;
>   listen           443 ssl;
>   server_name      images.nginx.org;
>   include images.location;
> }
> [/code]
> 
> We encounter the following error trying to install the configuration:
> [code]
> [emerg]: a duplicate listen options for 0.0.0.0:443 in
> /usr/local/etc/nginx/projects/proj.conf:19
> [/code]
> 
> All of the server names are CNAMEs of one IP address.
> 
> If I do the following, it works:
> 
> [code]
> ssl_certificate      common.crt;
> ssl_certificate_key  common.key;
>  
> server {
>   listen           80;
>   server_name      www.nginx.org;
>   ...
> }
>  
> server {
>   listen           443 default ssl;
>   server_name      secure.nginx.org;
>   ...
> }
>  
> server {
>   listen           80;
>   server_name      images.nginx.org;
>   include images.location;
> }
>  
> server {
>   listen           443;
>   ssl on;
>   server_name      images.nginx.org;
>   include images.location;
> }
> [/code]
> 
> Why can I not specify like the first example above?

Socket can't be in ssl mode for some servers and in non-ssl for 
others, so there is no need to specify "ssl" argument for 
non-default servers.  I.e. this will work with ssl in both 
servers:

server {
    listen 443 default ssl;
    ...
}

server {
    listen 443;
    ...
}

In your first configuration nginx was able to detect that you used 
meaningless "ssl" argument in second server and complained.  In 
second configuration it wasn't able to detect meaningless "ssl 
on;" statement.  This is the only difference.

Maxim Dounin