check Linux password from /etc/shadow and C language

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Using the encrypted password of the shadow file

i have an application that uses the encrypted password that's in the /etc/shadow file. i copied the line for the particular username i was interested it in from shadow file and i pasted it into the password file of the application. the application is nagios. this application allowed that...

2. Shell Programming and Scripting

Users who have never changed their password from /etc/shadow.

Hello, I have to do a script which returns users who have never changed their password from /etc/shadow. Here is what have I done and I'm not sure if it's ok. I tried to return just users who doesn;t have password set or are locked. Can be there other kind of user who never changed the...

3. Red Hat

Shadow file password policy

Today i was going through some of security guides written on linux . Under shadow file security following points were mentioned. 1)The encrypted password stored under /etc/shadow file should have more than 14-25 characters. 2)Usernames in shadow file must satisfy to all the same rules as...

4. UNIX for Advanced & Expert Users

/etc/shadow encrypted password

Hi I wonder whether is possible to generate enrypted passwd for some user and paste it into /etc/shadow file ? What kind of encryption is used in /etc/shadow file ? ths for help.

5. Solaris

Password Recovery From /etc/shadow file

Is it possible to reset a normal user password , by editing password field in /etc/shadow file? Thanks

6. Solaris

hash password in shadow show 'x' ???

Hello, I want to know the reason behing the scene why some systems have hashed password in /etc/shadow file as "x" not the alienoid language like A1Dksxi3kaA.. (13 characters) As far as I understand, etc/password will show password as "x" and move all hashed password to etc/shadow....

7. Linux

Interpreting the encrypted shadow password?

We are currently using a script to copy the same encrypted password between our HP-UX and Solaris servers editing the trusted and shadow files directly. The encrypted password is only 13 characters long on both servers and decrypts the same way. Is there a way to copy this same string to Linux...

8. UNIX for Dummies Questions & Answers

shadow file after a password reset

hi, I had to reset a lost root password by editing the /etc/passwd and /etc/shadow files ( this is a xen vm file, so i mounted and chrooted the file ) after the reboot with an empty password on root , i have set a new password with passwd but it only changed the /etc/passwd file....

9. Shell Programming and Scripting

I want to append password in /etc/shadow file

Hi, I want to append password into /etc/shadow file using a shell script. My below script does add the users to both /etc/passwd and /etc/shadow but how can I add the hordcoded passwords to /etc/shadow file can some one help me ? # To add the groups into /etc/group file for a_user...

10. UNIX for Dummies Questions & Answers

remove shadow password

Does anyone know how to remove a stanza in the shadow password file if the user account has already been removed on an AIX box? I know it can be done by editing the file itself but I would prefer not to do it that way. cheers gizaa

LEARN ABOUT MINIX

crypt

CRYPT(3)						     Library Functions Manual							  CRYPT(3)

NAME

       crypt - one-way password encryption function

SYNOPSIS

       #define _MINIX_SOURCE 1
       #include <unistd.h>

       char *crypt(const char *key, const char *salt)

DESCRIPTION

       The  first  use	of  crypt()  is  to encrypt a password.  Its second use is to authenticate a shadow password.  In both cases crypt() calls
       pwdauth(8) to do the real work.

       Crypt() encrypts a password if called with a user typed key, and a salt whose first two characters  are	in  the  set  [./0-9A-Za-z].   The
       result  is  a  character  string in the [./0-9A-Za-z] alphabet of which the first two characters are equal to the salt, and the rest is the
       result of encrypting the key and the salt.

       If crypt() is called with a salt that has the form ##user then the key is encrypted and compared to the encrypted password of user  in  the
       shadow  password  file.	If they are equal then crypt() returns the ##user argument, if not then some other string is returned.	This trick
       assures that the normal way to authenticate a password still works:

	      if (strcmp(pw->pw_passwd, crypt(key, pw->pw_passwd))) ...

       If key is a null string, and the shadow password is a null string or the salt is a null string then  the  result  equals  salt.	 (This	is
       because the caller can't tell if a password field is empty in the shadow password file.)

       The key and salt are limited to 1024 bytes total including the null bytes.

FILES

       /usr/lib/pwdauth 	The password authentication program

SEE ALSO

       getpass(3), getpwent(3), passwd(5), pwdauth(8).

NOTES

       The result of an encryption is returned in a static array that is overwritten by each call.  The return value should not be modified.

AUTHOR

       Kees J. Bot (kjb@cs.vu.nl)

																	  CRYPT(3)

Programming