Is it permissible for parents to prevent their son from talking to people online due to their fear of harm?

Obedience to parents is obligatory in matters where they have a legitimate purpose and which do not cause harm to the child. It is obligatory to obey them even if they are disobedient (fasiq), provided that there is benefit for them and it does not cause harm to the child. If their prevention of the child from talking to people online has a legitimate reason, then obedience to them is obligatory. If their prevention has no legitimate reason, then obedience to them is not obligatory, but one must deal with them kindly and avoid angering them. One should present the question to scholars in your country so they can investigate and answer based on what becomes apparent to them. If the parent's command or prohibition stems from foolishness, it should not be heeded. Nevertheless, one must be extremely cautious about disobeying parents, and one should not proceed with it except after consulting knowledgeable and trustworthy people of faith and intellect. If they find a legitimate excuse, then obedience is obligatory, otherwise not.