John the Ripper

Loomer

Anyone know much about this program. I was reading through the Docs and it was saying you have to copy the passwd file but be logged on as root? I thought the whole point of it was that you are able to crack passwords hence log on as root. I tryed running it on passwd as a normal user and it returns 0 words. Any help?

wintermute

John the Ripper, like other password crackers is designed to detect weak passwords from a password hash file that you already obtained. It's more of a system administrator's tool than a hacker one.

It would only be useful to a hacker if password shadowing was not turned on on the box in question or they wanted to get a list of user passwords from an already breached system.

How UNIX authentication works:

http://uw7doc.sco.com/SEC_admin/_Identification_and_Authenticati.html



[This message has been edited by wintermute (edited 29-06-2001).]

ObeyGiant

A lot of programs need to be able to view the passwd file. For them to do this, the passwd file must be world-readable, which inevitably leads to lusers trying to crack it. To get around this, the system of "shadow"ing a passwd file was introduced. What this means is that you have the world-readable /etc/passwd file, which contains user information, but no actual passwords, and the root-only-readable /etc/master.passwd (varies from system to system), which DOES contain passwords. You must have been trying to crack the wrong passwd file.

man 5 shadow

Loomer

Thanks guys, interesting info

dahamsta

Works a charm too. I ran it on one of my boxes a while back and it cracked one users passwords in a minute or so. Got another couple after a while too. Good for security - run it via cron every day, have it send an email to "offenders" telling them to change their passwords, and disable their accounts if they don't (BAD LUSER!).

adam

Loomer

Exactly what I was thinking of Tomo - Thx for the help