I've been using linux since 2002, I've never had to connect to the internet using root except with package managers. Router firewalls protect the local network, from the wide area network......you can still be vulnerable locally. If you only have family on your local network, and you are still scared of getting hacked....thats a personal issue. Firewalls are a great means of protection, but only if you know how to use it. And there isn't one particular default that can suit everyones purposes so its best that people enable & configure it to their needs where appropriate. In all my time using Linux I've never had a security breach that actually did anything noteworthy. The funny thing is that the only time someone got through is because I had a ridiculous password set (which is common with a majority of computer users), and they guessed it....once I set more complex passwords I could leave my firewall wide open, and never again had a problem. If you are a windows user......YES YOU NEED A FIREWALL because as mentioned by fellow users on here Windows is much more vulnerable then Linux. MUCH more. A resourceful novice could find a way to hack into your box. With Linux...only a knowledgeable user has a chance at that, and even then its extremely difficult. Thus why Linux is the popular choice for Servers. Security and stability. I can't name a single windows box that can go more then a year without ever being shutdown or rebooted. Heck windows can't even update without rebooting. That ridiculous if you ask me. And of all the users I've ever met for either Operating system...very few have ever had a direct need for a firewall. Its not necessary to turn on by default for just a few people who demand it While the many get by just fine without it.