Get hostname from request

Question

I'm running my application on Windows Server 2008 on an Intranet.

To login the application tries to get the hostname from the request to validate the user. However, sometimes the application returns the IP address instead of the name and some time later, without doing anything the application is able to resolve the name and everything works fine...

This is the code I'm using to get the hostname:

InetAddress inaHost = InetAddress.getByName(request.getRemoteAddr());
String hostname = inaHost.getHostName();
System.out.println("[[ Hostname = " + hostname + " ]]");

Is this because of the Intranet configuration (DNS!?), or is something wrong with my code, or witchcraft or something?

Negative

Why all this reflection? – Eckman

Sorry about the reflection. It was some "leftover" code from another approach I was trying. My bad. – Negative

Answer 1

First try

System.out.println("Host = " + request.getServerName());
System.out.println("Port = " + request.getServerPort());

if doesnt work

hostName == null;
Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
{
  while (interfaces.hasMoreElements()) {
    NetworkInterface nic = interfaces.nextElement();
    Enumeration<InetAddress> addresses = nic.getInetAddresses();
    while (hostName == null && addresses.hasMoreElements()) {
      InetAddress address = addresses.nextElement();
      if (!address.isLoopbackAddress()) {
        hostName = address.getHostName();
      }
    }
  }
}

Allie

Unfornately, neither approach worked. The first one returned the IP address and the second one returned the hostname from where my application is running. Perhaps I didn't explain myself well. What I would like is to get the name of the remote users machine. – Negative

can you try request.getRemoteHost() – Allie

returned the IP as well. but what I would really like to know is why my code works the way I want 95% of the time, and the other 5% only the IP address is returned – Negative

Please see my answer why it happens – Allie

Finally i got solution to your question just try the code snippet – Allie

This code still gets the server's own hostname(s). Your other answers ditto. Don't answer multiple times, please delete. – Thread

Answer 2

You will need to use the following function to get the remote address/hostname:

request.getRemoteHost();

Schipperke

Answer 3

sometimes the application returns the IP address instead of the name

As referenced from this SO answer:

The issue could be since request.getRemoteHost() does a reverse DNS lookup instead of taking it from the HTTP headers; if it fails to look up the DNS information using the IP, it returns the IP address as a String.

Simonsimona