Users information

July 4, 2016   

These are list of files, related to user information, and dealing with encrypted password.

Files: group, passwd and shadow

These are the files that contains information about users.

cat /etc/group

This contains a list of groups and their users.

$ cat /etc/passwd

This contains a list of users and their home path and shell path

all users can read this

# cat /etc/shadow

This contains a list of users with their encrypted password.

Just the root user can read this

Encryption method:

man 3 crypt

format

$id$salt$encrypted

Id

id => method of encryption 1 => MD5 2a => Blowfish 5 => SHA-256 6 => SHA-512

Salt

salt is a two-character string chosen from the set [a–zA–Z0–9./]

Encryption

Based on the id and the salt the encrypted password will generate

format

sha(salt + password)

References:



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