Having a computer connected to the Internet without a firewall is not recommended. Having a mind connected to the social world without a firewall is total madness. Many people advise against having barriers in life, to avoid missing great experiences. I think the opposite is true: no matter how big are you barriers, they are not big enough. Society will literally shower you with packets through all imaginable ports, and you have just three options: accepting, rejecting and dropping them.
If you accept them, i.e. if your are nice, be ready to eat an infinite amount of shit. There is no social world where you are nice and not eating shit all the time. That is, of course, if you define niceness as the habit of responding yes to everything. Another alternative is trying to still be nice by considering everything that comes at you, evaluating it, saying yes to what seems reasonable and kindly rejecting what does not. This is an infinite amount of work, and you will end up eating lots of shit anyway. Evaluating shit is almost shit eating. The third choice is simply to drop whatever you don't like. Without any answer. Just ignoring the request.
If you choose to be nice, you will end up looking nice only to your eyes. Don't even begin to think people will consider you a nicer person for that. If you choose to reject packets, in addition to the absurd amount of work trying not to offend anyone, you will not receive respect for that. You may think that ignoring someone is a lack of respect, while answering `no' is a better attitude. Sure, ignoring someone is the worst you can do, but every person is basically ignored by almost everyone, so the blame is shared and diluted, whereas a respectful rejection will stand out from the background and you will be the only recipient of rejection-related hate.
Conclusion: dropping any packet, ignoring every request without an answer is the only way to keep sanity in this society. Just don't rebounce anything, don't show your cards, stay silent.
Will you be nice and allow everything *by default*, with some blocking exceptions, or will you drop everything by default and allow some exceptions? Default rules come first, and everything else depends on how you define them in the first place. Don't even doubt it: drop everything by default and open exceptions.
Focus is narrow attention to a port. Awareness is wide attention to all ports. Alternate these two important disciplines with wisdom. A firewall needs to be permanently aware, and this is the only way it allows the mind to safely and temporarily focus on a single channel, either for productivity or for true enjoyment.
If you close everything by default, your awareness will only need to be as wide as the range of your exceptions, needing only a residual attention for the rest. If you block in a case-by-case fashion, your awareness will rapidly be overwhelmed and fail. Surely, by blocking everything by default, you will miss lots of things, even lots of very interesting things. However, without a block-by-default you will not be able to truly enjoy anything, so you would not truly miss anything, since you would miss it anyway.
Despite having only a few ports open, you will still need to watch and carefully select what tries to go through them. For these ports, add blocking exceptions based on every possible filter.
It is usual to focus on incoming dangers, but what about the ones coming from inside? Society can bury you with incoming packets, but you could also be a source of noise for others and yourself. Perhaps you talk too much, perhaps you give unnecessary and unrequested information. Once again, define a default rule of denying everything going out and add only those exceptions you carefully consider. This will also relieve your awareness and allow you to focus on what deserves going out. Again, for those ports that need to be open, add as many blocking conditions as you can.
As summary, drop by default, relieve awareness to only care about positive exceptions, and then add negative filters through those allowed channels.
You may think that whatever comes out of you is you. I beg to differ. Most of the output you emit is in fact a product of software and hardware that has been implanted in you, so your mind is not only flooded inwards: it is also overwhelmed outwards. Assume your mind is hacked and observe what tries to go out from it. While for incoming information you don't need to monitor everything trying to penetrate (you would never end and would not learn a lot), for outgoing packets it is extremely recommended to monitor everything carefully. You will see an avalanche of packets originating from inside that, upon inspection, are not recognised as yours. Then, who are sending them? What are the origins of these packets? Try to trace their sources. If they come from software, who installed it and under whose influence? Remove as much as you can. If it is hardware, can you rewire it? Most of the times you can, with patience.
Acknowledge you have two firewall layers: one at the level of the prefrontal cortex, costly to maintain and unstable when tired, and another at the level of the basal ganglia, efficient and stable even under difficult situations.
The prefrontal firewall allows you to write rules quite easily, but under stress, tiredness or any moderate-to-strong fluctuation it will cease working. It is unstable, inefficient and its daemon easily gets killed.
The basal firewall is the opposite: it keeps running no matter what, with a low maintenance cost and with high reliability. However, you don't have direct access to write rules on it. This firewall only accepts commits from the prefrontal counterpart, through the pushing of habit and perseverance. Only when a rule is maintained at the prefrontal level for long enough it becomes accepted at the basal domain.
Raise your firewall, in but also out, since out is also targeted and delayed in. For incoming, select your input. For outgoing, direct your output. Drop (without rejection) everything by default and open positive exceptions, and curate them with further negative filters. Underwhelm your awareness with default policies and cultivate your focus on the actual content you allow to flow. Monitor what pushes outwards and proceed to debloat, debug and purge your mind. Rewire yourself. Review and persevere, and commit your rules to the basal layer.
Once this is achieved you will be in control of your mind space, time and energy. This is nicer than being nice.
(This post is a small summary of many gripping conversations with mai and unicorn about this topic.)