Use Nginx as a Reverse Proxy to serve multiple web sites

Due to save IPs, I tried to use Nginx as a reverse proxy to serve multiple web sites.

server {
    listen 80;
    server_name server1.mydomain.com;

    location / {
        proxy_pass http://10.10.10.1/; #server1 internal IP
    }
}

This will cause 403 Forbidden error. I found the answer, add three lines:

server {
    listen 80;
    server_name server1.mydomain.com;

    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://10.10.10.1/; #server1 internal IP
    }
}

When I restart Nginx, will cause a warning:

[emerg]: could not build the proxy_headers_hash, you should increase either proxy_headers_hash_max_size: 512 or proxy_headers_hash_bucket_size: 64

I found this solution. Finally I modified the config to this:

server {
    listen 80;
    server_name server1.mydomain.com;

    location / {
        proxy_headers_hash_max_size 51200;
        proxy_headers_hash_bucket_size 6400;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass http://10.10.10.1/; #server1 internal IP
    }
}

Everythins is fine!

Notice:
    if use ssl, every site sould use its own certificate, for example:

 server {
        listen       443 ssl;
        server_name  server1.mydomain.com;

        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_headers_hash_max_size 51200;
        proxy_headers_hash_bucket_size 6400;
        ssl_certificate      /etc/ssl/server1.mydomain.com.crt;
        ssl_certificate_key  /etc/ssl/server1.mydomain.com.key;

        ssl_session_cache    shared:SSL:1m;
        ssl_session_timeout  5m;

        ssl_ciphers  HIGH:!aNULL:!MD5;
        ssl_prefer_server_ciphers  on;
        location / {
           proxy_pass http://10.10.10.1/; #server1 internal IP
    }
}