01. How do I access the password file under Unix?

In standard Unix the password file is /etc/passwd. On a Unix system with
either NIS/yp or password shadowing, much of the password data may be
elsewhere.

02. How do I crack Unix passwords?

Contrary to popular belief, Unix passwords cannot be decrypted. Unix
passwords are encrypted with a one way function. The login program encrypts
the text you enter at the "password:" prompt and compares that encrypted
string against the encrypted form of your password.
Password cracking software uses wordlists. Each word in the wordlist is
encrypted and the results are compared to the encrypted form of the target
password.
The best cracking program for Unix passwords is currently Crack by Alec
Muffett. For PC-DOS, the best package to use is currently CrackerJack.

03. What is password shadowing?

Password shadowing is a security system where the encrypted password field
of /etc/passwd is replaced with a special token and the encrypted password
is stored in a separate file which is not readable by normal system users.
To defeat password shadowing on many (but not all) systems, write a program
that uses successive calls to getpwent() to obtain the password file.
Example:

#include
main()
{
struct passwd *p;
while(p=getpwent())
printf("%s:%s:%d:%d:%s:%s:%s\n", p->pw_name, p->pw_passwd,
p->pw_uid, p->pw_gid, p->pw_gecos, p->pw_dir, p->pw_shell);
}

04. Where can I find the password file if it's shadowed?

Unix                  Path                            Token
-----------------------------------------------------------------
AIX 3                 /etc/security/passwd            !
          or             /tcb/auth/files//
A/UX 3.0s             /tcb/files/auth/?/*
BSD4.3-Reno           /etc/master.passwd              *
ConvexOS 10           /etc/shadpw                     *
ConvexOS 11           /etc/shadow                     *
DG/UX                 /etc/tcb/aa/user/               *
EP/IX                 /etc/shadow                     x
HP-UX                 /.secure/etc/passwd             *
IRIX 5                /etc/shadow                     x
Linux 1.1             /etc/shadow                     *
OSF/1                 /etc/passwd[.dir|.pag]          *
SCO Unix #.2.x        /tcb/auth/files//
SunOS4.1+c2           /etc/security/passwd.adjunct    ##username
SunOS 5.0             /etc/shadow

System V Release 4.0  /etc/shadow                     x
System V Release 4.2  /etc/security/* database
Ultrix 4              /etc/auth[.dir|.pag]            *
UNICOS                /etc/udb                        *




This page was created Wed Aug 11 23:45:00 EDT 1999


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 version 2.0.32
 on an i586

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