How to Change Originating Ip in Httpwebrequest

how to change originating IP in HttpWebRequest

According to this, no. You may have to drop down to using Sockets, where I know you can choose the local IP.

EDIT: actually, it seems that it may be possible. HttpWebRequest has a ServicePoint Property, which in turn has BindIPEndPointDelegate, which may be what you're looking for.

Give me a minute, I'm going to whip up an example...

HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://stackoverflow.com");

req.ServicePoint.BindIPEndPointDelegate = delegate(
    ServicePoint servicePoint,
    IPEndPoint remoteEndPoint,
    int retryCount) {

    if (remoteEndPoint.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6) {
        return new IPEndPoint(IPAddress.IPv6Any, 0);
    } else {
        return new IPEndPoint(IPAddress.Any, 0);
    }

};

Console.WriteLine(req.GetResponse().ResponseUri);

Basically, the delegate has to return an IPEndPoint. You can pick whatever you want, but if it can't bind to it, it'll call the delegate again, up to int.MAX_VALUE times. That's why I included code to handle IPv6, since IPAddress.Any is IPv4.

If you don't care about IPv6, you can get rid of that. Also, I leave the actual choosing of the IPAddress as an exercise to the reader :)

Change originating IP - circumventing caching of connections

Using HttpWebRequest.ConnectionGroupName you should be able to get around the ServicePoint connection reuse.

var hr = (HttpWebRequest)WebRequest.Create("http://google.com?");
hr.ConnectionGroupName = hr.RequestUri.ToString(); //Different connection pool per url. Might be better to make this random.
hr.GetResponse();

Alternatively you can just force close the group using ServicePoint.CloseConnectionGroup. The default group is null.

var hr = (HttpWebRequest)WebRequest.Create("http://google.com");
hr.ServicePoint.CloseConnectionGroup(null);
hr.GetResponse();

How to send httpwebrequests through specific ip address

Taken from this question

HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://stackoverflow.com");

req.ServicePoint.BindIPEndPointDelegate = delegate(
ServicePoint servicePoint,
IPEndPoint remoteEndPoint,
int retryCount) {

if (remoteEndPoint.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6) {
    return new IPEndPoint(IPAddress.IPv6Any, 0);
} else {
    return new IPEndPoint(IPAddress.Any, 0);
}

};

Console.WriteLine(req.GetResponse().ResponseUri);

HttpWebRequest to different IP than the domain resolves to

One way to spoof a HTTP host header is to set a proxy to the actual server you'd like the request sent to. Something like

request.Proxy = new WebProxy(string.Format("http://{0}/", hostAddress));

may well work.

Using Client IP address in HttpWebRequest

This is impossible. My answer to the other question was about selecting which IP Address (read: network adapter) to use for a request. However, you cannot invent IP Addresses out of thin air, nor use IP Addresses that are not yours (in a physical, attached-to-this-computer sense).

Now, technically, using Raw Sockets, you can spoof another IP Address in your packets. However, the problem with that is that the return traffic will go to the IP Address you specify, not the one you actually have!

So, my advice is to not pursue this line of thought any further, and find another way to do whatever it is that you are trying to do.

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