Want to find the IP Address of a machine, of the current machine? You can see this link where it’s explained the way to do this:

void CheckHostname()
{
	// ipaddress
	IPHostEntry localaddrs = Dns.GetHostByName(Dns.GetHostName());
	_hostname = string.Format("{0} ({1})", localaddrs.HostName, Array2String(localaddrs.AddressList));
}

private string Array2String(IPAddress[] iPAddress)
{
	List<string> result = new List<string>();
	if (iPAddress != null)
		foreach (IPAddress ip in iPAddress)
			result.Add(ip.ToString());
	return string.Join(", ", result.ToArray());
}