Hello All,

Can someone please give me any insight on how the passwords in /etc/shadow are encrypted? I am attempting to develop a script that will update /etc/shadow with a new user password, but I don't know how the passwords are encrypted/hashed.

Also, is there a way to run /usr/bin/passwd so the password is updated automatically? (That way, I won't have to deal with /etc/shadow at all)

For example:

Instead of

Lastly, I looked at the stdin option: "--stdin read new tokens from stdin (root only)"

Is there a way to run passwd --stdin username and then send the new password to passwd through a script?

Thanks in advance.

Hi,

I'm not used to deal with passwords, but it seems that they are encrypted using the crypt() function (see crypt(3) manual page), wich implements the DES algorithm.

I don't know what do you mean with:
I haven't found the "--stdin" option in passwd.

Thanks, I'll look into the crypt function.

What distro are you using? I'm running FC3. Check http://unixhelp.ed.ac.uk/CGI/man-cgi?passwd for more info... it includes the --stdin thing.

I'm using Debian SID, and I'm almost sure that the man page of passwd of my distribution doesn't say a word about the --stdin option.

Maybe your version of passwd is different, because I know mine does. I'm running FC3.