Reindl Harald wrote:
Am 24.03.2014 12:47, schrieb Gedalya:
On 03/24/2014 07:34 AM, Jürgen Ladstätter wrote:
we use dovecot 2.0.9 and authentication against a mysql database. Everything
works fine, but we found some weird behavior – when the password is e.g.
“testpass” you also authenticate successfully with “testpass123” or
“testpassNOT”. Whatever comes after the correct password doesn’t matter, the
authentication is still successful.
..
default_pass_scheme = CRYPT
http://wiki2.dovecot.org/Authentication/PasswordSchemes --
CRYPT: Traditional DES-crypted password in /etc/passwd (e.g. "pass" =
vpvKh.SaNbR6s)
Dovecot uses libc's crypt() function, which means that CRYPT is usually able to
recognize MD5-CRYPT and possibly
also other password schemes. See all of the *-CRYPT schemes at the top of this
page.
*The traditional DES-crypt scheme only uses the first 8 characters of the
password, the rest are ignored.* Other
schemes may have other password length limitations (if they limit the password
length at all)
my passwords have 19 chars and my linux login does not accept only
the first 8 ones, that's the state for many years now
Because libc's crypt() was extended to support other encryption
algorithms and your distribution chose to use them. (in Debian see for
example /etc/login.defs, variable ENCRYPT_METHOD)
That doesn't change the fact you can still use crypt() with DES
encryption. For example, htpasswd still does that by default (or at
least was doing that few months ago), you can recofigure your Linux
login to do it as well and obviously you can configure Dovecot the same way.
frankly 8 chars is laughable, i recently wrote a PHP library to
generate secure random passwords and for 100000 passwords get
13 collisions is way to much given that that means you have
a collision every 8000 tries which means not you need 8000
in a real world attack
GENERATED: 100000
COLLISIONS: 13
Yes, AFAIK DES encryption is obsolete for very long time and if you know
hash, it's quite easy to generate a secret which will match the hash (so
security-wise database with DES encrypted passwords is pretty much no
better than database with plaintext passwords)
For the author of top post: Dovecot does what you told it to do. If you
want to change this, it'll be a bit of a problem.
If you by any chance have plaintext passwords for your accounts (and you
shouldn't have them), you can pass them to
doveadm pw -s SHA512-CRYPT -p plaintext
and store what comes out to your DB.
If you don't have them, there's a way using postlogin script -
http://wiki2.dovecot.org/PostLoginScripting , see
http://wiki2.dovecot.org/HowTo/ConvertPasswordSchemes
This method will however convert scheme for _first_ password that allows
someone to login. So you can expect complaints from your users who use
their account from two devices with different passwords (with difference
after 8th character.) They will login from one device, password scheme
changes and the other device will be locked out.
