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User1
Asked: 2010-11-10 09:29:33 +0800 CST

What happens when you chmod 600 /etc/passwd?

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Yes, yes I know there are no real passwords or even hashes in that file on modern systems. However, I am quite curious if this is a good, easy way to totally lock down a system from everyone and what would break first. I don't have a spare system, but it sure sounds like a fun experiment. Has anyone tried this?

linux

2 Answers

  1. Best Answer

    Just for you I tried it :-)

    Any user will be able to login like normal. This is because login runs with root privileges. After being logged in the user won't have access to /etc/passwd which might cause problems with userland applications.

    The first thing you might notice is that the shell cannot read your username which produce a prompt like

    I have no name!@vs245042:~$
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  2. Setup an auditctl on /etc/passwd and see what tries to access it:
    auditctl -w /etc/passwd -p war

    Then afterwards analyse the output of:
    ausearch -f /etc/passwd

    See what's trying to access it, if it's all root processes then you're fine.

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