I have the following configuration for a basic load balancing setup:

http {
upstream backend {
ip_hash;
server 192.168.1.12:80;
}

server {
listen 80;
location / {
proxy_pass http://backend;
}

}
}

The problem I have, is although it proxies correcltly to the back server (just one as this is a test.) All the urls in the resulting page get rewritten to "http://backend", causing the page to render incorrectly. How do I prevent this?

NM. My code is doing something is should not.

Actually, it appears that it's passing "backend" as the SERVER_NAME from the browser. Any way to prevent this?

I think you need to use:

proxy_set_header Host $host;

or you could put a string in there is you would like. That should set the host name for the request. This is set to "proxy_set_header Host $proxy_host;" by default. Can you look at what the host header is on the upstream server to confirm that it's set to "backend" instead of the host name?