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UNIX for Dummies Questions & Answers
How to : Identify the the password is encrypted or not in /etc/shadow or /etc/passwd?
Post 302283157 by Ikon on Monday 2nd of February 2009 05:21:03 PM
02-02-2009
As stated before /etc/shadows passwords are encrypted.
1) Username: It is used when user logs in. It should be between 1 and 32 characters in length.
2) Password: An x character indicates that encrypted password is stored in /etc/shadow file.
3) User ID (UID): Each user must be assigned a user ID (UID). UID 0 (zero) is reserved for root and UIDs 1-99 are reserved for other predefined accounts. Further UID 100-999 are reserved by system for administrative and system accounts/groups.
4) Group ID (GID): The primary group ID (stored in /etc/group file)
5) User ID Info: The comment field. It allow you to add extra information about the users such as user's full name, phone number etc. This field use by finger command.
6) Home directory: The absolute path to the directory the user will be in when they log in. If this directory does not exists then users directory becomes /
7) Command/shell: The absolute path of a command or shell (/bin/bash). Typically, this is a shell. Please note that it does not have to be a shell.
Your encrpted password is not stored in /etc/passwd file. It is stored in /etc/shadow file. In the good old days there was no great problem with this general read permission. Everybody could read the encrypted passwords, but the hardware was too slow to crack a well-chosen password, and moreover, the basic assumption used to be that of a friendly user-community.
Almost, all modern Linux / UNIX line operating systems use some sort of the shadow password suite, where /etc/passwd has asterisks (*) instead of encrypted passwords, and the encrypted passwords are in /etc/shadow which is readable by the superuser only.
1) Username: It is used when user logs in. It should be between 1 and 32 characters in length.
2) Password: An x character indicates that encrypted password is stored in /etc/shadow file.
3) User ID (UID): Each user must be assigned a user ID (UID). UID 0 (zero) is reserved for root and UIDs 1-99 are reserved for other predefined accounts. Further UID 100-999 are reserved by system for administrative and system accounts/groups.
4) Group ID (GID): The primary group ID (stored in /etc/group file)
5) User ID Info: The comment field. It allow you to add extra information about the users such as user's full name, phone number etc. This field use by finger command.
6) Home directory: The absolute path to the directory the user will be in when they log in. If this directory does not exists then users directory becomes /
7) Command/shell: The absolute path of a command or shell (/bin/bash). Typically, this is a shell. Please note that it does not have to be a shell.
Your encrpted password is not stored in /etc/passwd file. It is stored in /etc/shadow file. In the good old days there was no great problem with this general read permission. Everybody could read the encrypted passwords, but the hardware was too slow to crack a well-chosen password, and moreover, the basic assumption used to be that of a friendly user-community.
Almost, all modern Linux / UNIX line operating systems use some sort of the shadow password suite, where /etc/passwd has asterisks (*) instead of encrypted passwords, and the encrypted passwords are in /etc/shadow which is readable by the superuser only.
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LEARN ABOUT DEBIAN
passwd
PASSWD(5) File Formats and Conversions PASSWD(5) NAME
passwd - the password file DESCRIPTION
/etc/passwd contains one line for each user account, with seven fields delimited by colons (":"). These fields are: o login name o optional encrypted password o numerical user ID o numerical group ID o user name or comment field o user home directory o optional user command interpreter The encrypted password field may be blank, in which case no password is required to authenticate as the specified login name. However, some applications which read the /etc/passwd file may decide not to permit any access at all if the password field is blank. If the password field is a lower-case "x", then the encrypted password is actually stored in the shadow(5) file instead; there must be a corresponding line in the /etc/shadow file, or else the user account is invalid. If the password field is any other string, then it will be treated as an encrypted password, as specified by crypt(3). The comment field is used by various system utilities, such as finger(1). The home directory field provides the name of the initial working directory. The login program uses this information to set the value of the $HOME environmental variable. The command interpreter field provides the name of the user's command language interpreter, or the name of the initial program to execute. The login program uses this information to set the value of the $SHELL environmental variable. If this field is empty, it defaults to the value /bin/sh. FILES
/etc/passwd User account information. /etc/shadow optional encrypted password file /etc/passwd- Backup file for /etc/passwd. Note that this file is used by the tools of the shadow toolsuite, but not by all user and password management tools. SEE ALSO
crypt(3), getent(1), getpwnam(3), login(1), passwd(1), pwck(8), pwconv(8), pwunconv(8), shadow(5), su(1), sulogin(8). shadow-utils 4.1.5.1 05/25/2012 PASSWD(5)