Well there is no precise way to protect your kids from online perverts, but you can take safety precautions, like sitting with your child when he is using the internet.

Though it will be difficult but try to explain the various ill effects of internet. Set guide lines tell them not to visit chat rooms and do not chat with strangers. If they using online messengers ask them only to add people they know. Set time limits for internet usage; allocate 1-2 hours maximum of internet usage for the child.

Perversion basically is an expression or thought which illustrates a particular kind of human behaviour that is a different from what is thought to be normal or orthodox behaviour.
Prior to the 20th century, the expression generally meant religious perversion, like altering one's religion to an erroneous one.

Program your pc not to allow them to beable to go to sites with adult content cussing nudity ect check history logs when they are on pc setup pc in open area use pc for education and let them use only fo certain ammont of time.