Clarification needed in security issues with Live CD

[nbalaji]

Hi all,
I installed Ubuntu 7.04 a week back and it is a single OS in my laptop. It is password protected and i am its lone user apart from root. Now, i put the Slax Live CD, reboot the machine and logged into KDE mode. It never asked any of my credentials to login. Now from Slax, i could access my hardisk and its contents including my files.
How could this happen? How can i protect my harddisk from these kind of accesses? Is it the same case with XP installed machine (i really wanted to know)?
Correct me wherever i am wrong.

Many thanks in advance,
Balaji N

[smolloy]

It is a common expression in the linux community to say that "Physical access means complete access" -- in other words, if someone has physical access to your machine, they have complete access to all files on that machine.

To help mitigate this, you could look into encrypting all the files on your Ubuntu installation. That would mean that the Slax user could see them all (and delete them!), but wouldn't be able to read their contents.

[nbalaji]

I am a newbie and remember this question during Ubuntu's installation. I just simply ignored it! Without this encryption, now if i loose my laptop, think my files would be safe at other hands.
What about BSD, Windows and Mac?

[smolloy]

I know you can see Windows files from a live CD, but I'm not sure about BSD and Mac. I'd guess they'd be the same.

Just remember, that if you lose your encryption passphrase, then you will lose access to all your files!! There is no way to get the passphrase back if you lose it!

[pavlo_7]

I know you can see Windows files from a live CD, but I'm not sure about BSD and Mac. I'd guess they'd be the same.

With Mac it's the same, one can reset root password by booting from install CD.
If someone really wants to see the files, he/she can easily take the drive out, attach it to another computer and mount the drive there (no Live CD needed). So, encrypting the content is probably the only protection at the moment.