How do I route web requests into my private network depending on the domain in the url?

Question

Scenario:

Due to limited number of IPs, several domains are resolved into the same IP address. However, these domains may not all run on the same webserver, VM, or even dedicated machine. Therefore, I would like to route the domains at the point of entry into the private network to the right place on condition of the domain in the url.

How can I do this?

Answer 1

Most routers/firewalls allow to redirect traffic based on a certain port, e.g. all SMTP traffic (port 25) is redirected to 192.168.1.1.

But if you have multiple servers to handle your traffic (1 server per domain). You need to install something like a reverse proxy (nginx supports this for HTTP, IMAP, POP3). For instance, all traffic to port 80 is redirected to 192.168.1.2 which runs nginx and depending on the host name will redirect to either localhost or 192.168.1.4.

Answer 2

I am unsure if I fully understand your question. If I do, you have multiple machines running as HTTP servers behind NAT. When some request arrives, you want to forward it to one of your servers, right?

If you are using apache and mod_rewrite, you might be able to pull it this way:

1. http://www.linuxquestions.org/questions/linux-networking-3/apache-forward-request-to-another-box-264864/

2. http://www.sematopia.com/2007/09/apache-forwarding-requests-to-another-server/

Cheers.

Answer 3

I have done something similar using the ProxyPass directive under mod_proxy in Apache.

First of all, use Name-based Virtual Hosting to allow different domains to be host different sites using the same IP, then for the domains that associated to an internal webserver, you have a config like so:

# Within your VirtualHost definition
ServerName somedomain.com
ProxyPass / http://10.0.1.42/
ProxyPassReverse / http://10.0.1.42/

This will result in all requests to http://somedomain.com be transparently proxied to an internal site hosted on http://10.0.1.42.

HTH

Answer 4

I was looking for the same thing a while ago. Never got around to do it but here is what I though might work.

use the mod_proxy module and use the noproxy directive.

http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#noproxy