reverse proxying towards various hardware devices

[Maxim Dounin]

Hello!

On Sat, Jan 23, 2010 at 04:45:07PM +0100, Paul Swielingen wrote:

> Hi all,
> 
> I need some help with NGINX reverse proxying setup.
> 
> The problem: make several devices accessible through a single IP
> address.
> my current configuration works:
> 1) For some devices: fine
> 2) For other devices: for a large part
> 3) For still other devices: hardly
> 
> I analyzed the reason for 2) and 3) above and it comes down to: as soon
> as such a device returns a page with links that starts with a / clicking
> the link fails.  The reason for this is that the reverse proxy no longer
> recognizes the request as destined for the particular device.
> 
> The relevant part from my nginx.conf file:
> 
>   server {
>     listen  xxxxx.yyyyyy.zzzz.com:80;
> 
>     location / {
>       root   /var/mine/data;
>       index  index.html;
>       }
> 
>     location /spa3000-1/ { # forward to device
>       proxy_pass http://spa3000-1.xxxxx.yyyyyy.zzzz.com/;
>       }
> ...
> similar configs for other devices
> ...
>     }
> 
> I am aware that I could destine all these devices to their own port but
> I don't want to do that because securing them will become very
> difficult. Therefore I don't want to take that path.
> 
> I know of the existence of referrers but I do not understand how to
> approach using that. Anybody can help me?

It's up to the device in question to form correct links on pages 
it returns.  If it doesn't do so - some limited changes may be 
done by sub filter module.  But it's not really a solution as it's 
not able to parse and interpret all of the returned code (even if 
teach it to parse html - what to do with broken html, javascript, 
css, xml+xslt and so on?).

So the only generic solution is to use separate hosts (or ports).  
You may still proxy them via nginx, i.e. write something like 
this:

    server {
        server_name device.example.com;

        location / {
            proxy_pass http://real-device.example.com;
            proxy_set_header Host $host;
        }
    }

and make sure device thinks it's called "device.example.com" while 
this name in fact points to nginx server.

Maxim Dounin