When you logged in to a Unix/Linux system, what files are checked to authenticate your username and password?

Question

When you logged in to a Unix/Linux system, what files are checked to authenticate your username and password?

Answer 1

On a small scale it isn't necessary but it will turn into a bad habit when you work as a sys admin at the enterprise level. Like somebody said if you run a delete command as root and it was the wrong file then there's a big headache there. When you're working on only one system it's very easy to focus and not make mistakes. When you're an admin you have your support team IM flashing for escalations, multiple root shells open to various servers, and managers pressuring side projects. If it's annoying to prepend your commands with sudo create an alias for it.

Answer 2

each user as a user folder and each user folder is checked against the password and user name,, one thing about linux is if you forget your password you will never get into your account...



now if your installing Linux onto your system you will need to open two accounts, a supper user account, and a user account, the supper user account is for the administrator and the user account is what your will normally sign into.



As a user you will not be able to install anything or alter anything within the system, you will be able to alter things within your user account,



if you would like to know more then PM me I will guide you to the tutorials on how to install Linux, and plenty of other tutorials....

Answer 3

start by checking the output of:

strings /bin/login | grep "^/"



or, better, find the source files of the package that "/bin/login" belongs to and study them!

Answer 4

The username and password are checked against an encrypted file in /etc/passwd for ubuntu, it may vary in other distros.

Answer 5

/etc/passwd contains the user name and (on base level security systems) the encrypted password.



On not base level secure systems the password is held in another file / directory structure. The location of this depends on the OS you are talking about and what level of security you are running. It may be in files under /etc/tcb or /usr/tcb or other places... have a look at the man pages for the OS you are working with.



Most Linux systems now run not-base-level security by default.



/etc/passwd is world readable and the password is encrypted. The secure password file structure is usually root-readable only. Plus the passwords are encrypted.

Answer 6

It depends on what authentication mechanism is used.



The basic answer though, is /etc/passwd

Answer 7

you realize that file is encrypted right?



and, it depends on your distro i think

Answer 8

If you are just using standard authentication:



/etc/passwd

/etc/shadow



You may also be set up to use Kerbos which is a centralized form of authentication. Sort of like Active Directory or LDAP. There are several other solutions as well.