What are the prerequisites for CEH course?

I think you're referring to the Certified Ethical Hacker course from EC Council. You don't need any formal qualifications as such because you can either pass the exam by enrolling at a training centre or through self-study.

The course is mostly based on networking so you should have a solid understanding of network protocols (IPv6 vulnerabilities, packet sniffing, spoofing, DNS etc).

You only need to attend the official CEH training course. Some uni in Malaysia were offering this course on a 5 day basis.

However if you opt to take the exam without attending the course,then you need to produce a valid work experience(security) of atleast two years from your employer.

In case you do not posses all of this then, you'll need to fill up a form on the eccouncil site with all your educational background so that they evaluate if you can take the exam of not.