Make an HTTP request to a machine but fake the hostname
Consider you have a website vhost listening to
www.example.com, redirecting all incoming requests that do not talk about the configured hostname (this is often used to redirect users to
http://www.example.com when entering only
If you want to make a request to that site's web server without actually talking to
www.example.com (e.g. because this is a load balancer's address but you want to access one specific machine), you cannot just request
localhost as the above vhost will redirect your request.
When talking HTTP 1.1, your client (browser) uses the HTTP header "
Host" to tell the web server what host it's requesting for. This is what we want to change in order to properly "fake" the request. You can do it in different ways, here are two:
Since version 7.21.3 cURL allows specifying an IP address, thus forging the hostname for the request.
$ curl --resolve www.example.com:80:127.0.0.1 http://www.example.com/
--resolve switch allows you to tell curl which address to request when it would resolve a given hostname. In the above snippet cURL uses
127.0.0.1 (localhost) instead of resolving
www.example.com via DNS.
Telnet (aka classic mode)
You can use telnet to speak HTTP, e.g. if your cURL is below 7.21.3:
$ telnet 127.0.0.1 80 GET / HTTP/1.1 Host: www.example.com <Return> <Return>
Here you make an HTTP 1.1 request manually. The
Host header tells the server that this request is for
www.example.com. Terminate your request headers by 2 linebreaks.