Hello,             My questions are - how do I detect a suspicious network connection? - what sort of computer security tips do people have? Some background information regarding the above questions. Firstly as some of you may have noticed I have very little to no knowledge in this area.I am flat out running a business that is barely paying bills and probably cannot afford to buy security software, hire someone or spend much time on a computer security course. I believe my computers are getting hacked.I have noticed files being changed/added in dropbox that I definitely hadn't changed/added myself.Also at times I am no longer able to easily change my password or do updates.Also I have noticed that at such times web browsing can become very slow as well as the general speed of my computer.I am running Linux Mint 18.My solution to computer security has been to change my user password several times a day which seems to help.I do updates regularly and use relatively low spec computers (dual core machines) so that if there is a problem and someone else is using my computer I can notice it more easily.I always use regular hard drives so that any possible hacking cannot be done too quickly.I have also written a program to change the hostname on my computers and this seems to speed up my computers and web browsing for a while.When web pages start malfunctioning,changing the user password and computer hostname very often fixes it. I have noticed that problems seem to be correlated with how many network connections I see.I am thinking of writing a program to shut down any suspicious network connections as long as I know how to detect them.Buying security software may seem more cost effective but I don't trust commercial products because the seller always has a vested interest to encourage hacking etc to continue the sale of products and maintain subscriptions. Unfortunately I have no computers that can run the latest Qubes Linux. regards Peter