Elaborate physical prevention-- some sort of lockdown-- on the computer doesn’t solve any problem. It will only divert the problem to escape through other routes.
First, it must be said that no program is completely impervious to assault. Do not underestimate the ingenuity of your son, ways can be found around this. Jamming a stopper into the bottle will not solve the problem.
The solution, I believe, lies in letting your son exercise his own self-control until he physically trains himself to reject this.
What he should not allow, nor should you, are for him to easily find occassions of sin. That is, occasions where he is tempted to sin. Occasions of sin are not sin themselves, but they lead to sin. This requires that some simple things be done. First, make sure that filters on Google are set to “moderate.” Like I said, if there’s a will, there’s a way around stringent barriers. The computer should be contructed so as to make it difficult to accidently stumble into occasions of sin, and hard to impossible to overtly search for such material. (Which I think using Google’s own “moderate safe search” does enough.)
What is important is that he learns himself 1. the depravity of it 2. the self-control to not do it again. Unfortunately, I don’t think he can develop that self-control unless he is in some way able to make that choice. And if he *doesn’t *learn that self-control, he won’t have it. And don’t tell me you seriously think you can control him when he goes to college, or even to friends’ houses now. You can’t. Only he can control himself, and that’s what needs to be nurtured.
Of course, also make sure he understands the positive aspects of human sexuality, Theology of the Body, etc… and the grounding in the faith why it is dangerous to continue in such a way.
Perhaps my methods sound too free. However, I am speaking as a seventeen year old male who knows very well that if I didn’t choose not to pursue pornography, that my parents would have no way of stopping me. Cultivate his conscience, feed his knowledge of Church teaching, allow him to practice self-control.
As a side note, all of use have slips in our self-control. A slip in self-control is not necessarily evidence that your son is again having this problem, merely that he, like myself and all other humans, is weak as the flesh is weak.
And as a side note to my side note, also impress on him that the desire to see these things is like a cycle that perpetuates itself. If you cut out unnecessary stimuli, you’ll find that it’s much easier to go without ‘craving’ such things, just as a quitting smoker would do best not to inhale the waft of smoke from another person.
-Rob