Question

I’m writing a port scanner to detect web services running on the local network. Some of these web services require basic authentication – I don’t know the username/ password for these services, I just want to list them, so I can’t provide the credentials at this stage. I’m using the code:

                    var request = (HttpWebRequest)WebRequest.Create("http://" + req);
                    request.Referer = "";
                    request.Timeout = 3000;
                    request.UserAgent = "Mozilla/5.0";
                    request.AllowAutoRedirect = false;
                    request.Method = WebRequestMethods.Http.Head;

                    HttpWebResponse response = null;

                    try
                    {
                        response = (HttpWebResponse) request.GetResponse();
                        // I want to parse the headers here for the server name but as the exception is thrown the response object is null.

                    }
                    catch (Exception ex)
                    {
                        //401 error is caught here - response is null
                    }

I’m then parsing out the server name from the headers that are returned – I know they are being returned because I can see them with fiddler but the HttpWebResponse object is set to null as the GetResponse() method is throwing an exception. Basically – how do I get it to not throw and exception but return the headers along with a status code of 401.

Answer 1

If you catch a WebException you’ll have access to ex.Response and you can retrieve your headers from there.