I spend a lot of time for this free version, but didn't find it . So NS2 or NS3 is best simulator and supportive it. 

I dont have idea

How about using OMNeT++ to create and build your own customized simulator.

QualNet is commercial software. Other than GloMoSim there is no (legally) free version. If you don't want to pay for a commercial network simulator, use NS3 or OmNeT++, which are free and cross-platform.

Thank you everyone for your valuable responses. I am already using OmNet++ but the thing is there is not much online support and tutorials available for both Omnet++ and NS3. Are there any sites that provides tutorial on these simulators? I am basically working on wireless IDS, so I am interested on modifying various routing protocols like AODV, DSR, WSR etc to learn how they react under various types of attacks.  

For your latest question Basant, regarding ns-3, you'll find on the official site (https://www.nsnam.org/) the documentation (essentially a tutorial to begin with, a manual to continue learning, a library documentation to dig deeper. All three documents can be fetched in nicely formatted PDF, among other formats. So, no book indeed, but those are close to a commercial book. Some sections are still blank (especially in the lib documentation, eg. for some propagation models) but it is regularly extended. Solid material.). The Doxygen-based reference documentation for each class/method on the official site is also useful. The ns-3 tarball, which is continuously updated (~ 3-4 releases per year), comes with AODV and DSR among other MANET routing protocols, many examples are provided to understand the basics of the use of each class/method/attribute/module. Additionally, the ns-3 Google groups is very active, you can ask questions (advise: think and express carefully your problem, make sure you have correctly searched related threads/posts previously exchanged on the group before duplicating a question or asking an obvious or ill-analysed question, etc.).

So all in all, I'd say ns-3 is now mature, well-maintained, well-documented, active and with a nice GPL v2 licence.

Omnet++ is equally interesting (excluding the licence in my opinion, unless you belong to Academia and don't use it in the context of government/EU-funded projects. For industry or SMEs or in the context of collaborative projects, the Academic Public Licence bars you from using Omnet++ and you'll need to use the commercial version instead, Omnest. So in your case, you would then be back to your GloMoSim/QualNet dilemma).

That being said, Omnet++ is an equally complete and nice discrete event network simulator, with an attractive integrated IDE (convenient to visualise simulation scenarios, in particular). But personally I'm happy with ns-3 + the Eclipse IDE.

So in brief, if for some reason you're unhappy with GloMoSim and belong to Academia, go for either ns-3 or Omnet++. Otherwise, if you don't want to use a commercial simulator, ns-3 is a nice choice. Regards.

QualNet is a commercial software. There is no free version. At most, you could ask for a 30-day trial license (http://web.scalable-networks.com/content/evaluation-programs).

Based on my experience, NS2, NS3 and OmNet are much better than QualNet in terms of:

1- Open source: it allows you to understand until any level of code. So, just dig into the code.

2- Extend-ability: it allows you to modify the existing classes or to add new classes.

3- Support: there is a large community of people who work on these simulators and they always available for support and discussion.

Thanks