tried them, either registration issues..or not good enough, is there any network modellor or simulator which would let me design my own packets and transmit them over a designated network design. I am trying my luck with OPNET right now.
What's not good enough with these tools? The apps nske suggested are all widely used. They are better than a lot of expensive security tools, IMHO. Are you looking for one with a GUI front-end because Nemesis is especially relevant to doing what you want to do? If you are looking for a GUI, try
what i need is a generator which will generate packets, not for a known protocol, it will let me generate packets of a new form, and yes, a GUI would be useful for taking screenshots, dos based generators wont be idea for taking screen shots. but either way i am weighing my options between using a ready made package, or designing my own.