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I don't have means to test this but I'm on Windows 7 and I set one of my HDD's (entire drive) permission to Administrators.

  1. If I plug it in another Windows 7 or Windows XP computer will the permissions work?
  2. If I plug it in a non-Windows OS (i.e., Linux or Mac), the permission will probably not work right and they will be able to read the contents of my drive?
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Are you simply curious or actually trying to protect data from an outsider or something else? – nerdwaller Oct 26 '12 at 18:12
The OS will enforce the permissions. But remember that anyone who has administrator/root access to a system can bypass its permissions anyway. – David Schwartz Oct 26 '12 at 18:26
@DavidSchwartz So the permission will work even if I plug it in Linux or Mac? – IMB Oct 26 '12 at 18:35
@nerdwaller If I upgrade my OS someday I want to know if I'll face some permission trouble – IMB Oct 26 '12 at 18:35
@IMB: In some sense, yes. The OS will map the filesystem's permissions to its own. Whether the result makes sense is another story. – David Schwartz Oct 26 '12 at 18:35
up vote 2 down vote accepted

1) Yes, other versions of the same OS will recognize them. However, they will be easily by-passable by an admin.

2) No, the permissions won't matter on Linux or Mac. Even if they did, anyone with sudoer's access can just change them.

Long story short is permissions are relatively arbitrary unless you are on a domain (where each user has their own log-in and belong to a non-elevated group) or you want to keep a non-techie (or another user of your pc) out [or at least make it more difficult for them].

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Permissions will not do anything to prevent an Administrator on another computer from reading your files if he has the hard drive.

What you want for that is encryption.

However, if you want to share files with friends for example, you can do that. Using Windows user accounts will not work (easily) because each user is really a GUID in the permissions settings. So Joe from one Windows machine will show up as {blah-blah-blah-blah-blah} on another machine. The Administrator, Everyone, LOCAL SYSTEM, etc accounts and groups use standard GUIDs that are the same on each machine though.

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I'd amend Zan's comment to say if you'd set all your permissions to only allow user 'fred' (for example) on your PC, and revoked all other access, then another Windows PC would respect that. However, an administrator on that PC could "Take Ownership" and override your permissions (obviously not without it being visible). That one correction aside, he's correct - you need to encrypt to secure it from anyone else. – PJC Oct 26 '12 at 18:56
@PJC: With the right software, or a dev environment, you can read files without taking ownership by using impersonation. – Zan Lynx Oct 26 '12 at 19:20

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