Algorithms like Naive-Bayes, Decision trees and Random Forests are designed and implemented over the data set of NSL-KDD. A complete visualization of attributes and also the output of algorithms is given. The entire process of training and classification is split up in modules so that it is easy for the developer to understand.

NSL-KDD data set is a refined version of its predecessor which is KDD cup 99 from DARPA. In each record there are 41 attributes unfolding different features of the flow and a label assigned to each either as an attack type or as normal. These 41 attributes are divided into 4 groups:

• Basic features
• Content related
• Time related features
• Host based traffic features:

The entire data and description can be found here: click here

The 4 main classes of attacks are:

• Denial of service (DoS)
• User to root (U2R)
• Remote to user (R2L)
• Probing

The attribute selection is the tricky part. Typical models like random forests, decision trees, etc take very long time to build the model. Hence, the number of attributes must be reduced. Moreover, there are many zero variance features which are removed in this step.

• Naive Bayes
• Decision Trees
• Random Forests

• The redundancy can be eliminated by finding out the zero-variance features and not including them in the training set as it leads to biased results.
• Once threshold efficiency is reached, any increase in the training set would only over-fit the data. Therefore the results would tend to deteriorate if training set is kept increasing.
• Instead the number of attributes taken to build the model can be increased to improve the results.
• Once trained, the model was also tested to find out how it would respond to attacks which are new. The models performed pretty well for even these un-trained new attack types.