Date: Thu, 18 Feb 2016 18:11:22 +0100 From: "O. Hartmann" <ohartman@zedat.fu-berlin.de> To: Ian Lepore <ian@freebsd.org> Cc: RW <rwmaillists@googlemail.com>, freebsd-current@freebsd.org Subject: Re: HELP: Howtwo create a passwd-suitable hash for usage with psswd -H 0? Message-ID: <20160218181122.29b8fae2.ohartman@zedat.fu-berlin.de> In-Reply-To: <1455812966.1294.5.camel@freebsd.org> References: <20160218141624.5f560f2d@freyja.zeit4.iv.bundesimmobilien.de> <20160218145244.0b1e4c94@gumby.homeunix.com> <20160218162908.4cf16f6b@freyja.zeit4.iv.bundesimmobilien.de> <1455812966.1294.5.camel@freebsd.org>
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[-- Attachment #1 --]
Am Thu, 18 Feb 2016 09:29:26 -0700
Ian Lepore <ian@freebsd.org> schrieb:
> On Thu, 2016-02-18 at 16:29 +0100, O. Hartmann wrote:
> > On Thu, 18 Feb 2016 14:52:44 +0000
> > RW <rwmaillists@googlemail.com> wrote:
> >
> > > On Thu, 18 Feb 2016 14:16:24 +0100
> > > O. Hartmann wrote:
> > >
> > > > Hello out there,
> > > >
> > > > I run into a problem and digging for a solution didn't work out.
> > > >
> > > > Problem: I need a string that reflects the hashed password for the
> > > > usage with
> > > >
> > > > passwd -H 0
> > >
> > > Did you mean -h?
> >
> > no, I literally mean -H 0, I explain later ...
> >
> > >
> > > > I think the procedure is using
> > > >
> > > > sha512 -s Password
> > > >
> > > > and using this output for further processing, but how?
> > >
> > > It's not as simple as that, password hashes are usually salted and
> > > iterated. Salting means that the password is combined with a randomly
> > > generated string stored in plaintext, which means that the password
> > > doesn't hash to a fixed string.
> > >
> > > I'm not sure exactly what you are trying to do, but crypt(3) may be of
> > > help.
> >
> > I'm now down to a small C routine utilizing crypt(3). But this is not what I
> > intend to have, since I want to use tools from the FBSD base system.
> >
> > I build images of a small appliance in a secure isolated environment via
> > NanoBSD. I do not want to have passwords in the clear around here, but I also
> > do not want to type in everytime an image is created, so the idea is to have
> > passwords prepared as hashes in a local file/in variables. Therefore, I'm
> > inclined to use the option "-H 0" of the pw(1) command to provide an already
> > and clean hash (SHA512), which is then stored in /etc/master.passwd.
> >
> > It is really funny: passwd or pw take passwords via stdin (-h 0 with pw) and
> > they "generate" somehow the hashed password and store that in master.password
> > - but I didn't find any way to pipe out the writing of the password to the
> > standard output from that piece of software. Why? Security concerns I forgot to
> > consider?
> >
> > I found lots of articles and howtos to use pipes producing the required
> > password hashes via passwd, chpasswd or pw, but they all have one problem: I
> > have to provide somehow the cleartext password in an automated environment.
> >
> > Maybe there is something missing ...
> >
> > oh
>
> We use something like this at work (which I don't fully understand, but
> it works on freebsd 6.x through 10.x at least)...
>
> echo ${password} | openssl passwd -1 -stdin -salt VerySalty | \
> pw -V ${IMAGE_CHROOT_DIR}/etc useradd -n ${username} -H0 $*
>
> I guess for your use you'd capture and save the output of openssl so
> you could later feed it back to pw when making images.
>
> -- Ian
The "openssl passwd -1" refers to MD5 hashes, as I understand the manpage, but I require
at least sha256. With this solution suggested, I'd have the password still stored
in cleartext somewhere - if not read -in via read or similar.
If you snip off the openssl portion and substitute "-H0" with "-h0", then this is the way
I did before - as defined/configured in login.conf (usually in
${IMAGE_CHROOT_DIR}/etc) SHA512 will be used as digest algorithm and the password seems
"salted", prepended by the $6$ characters.
I'd like to have something like
echo ${password} | openssl passwd -sha512 -stdin -salt VerySalty
and store the result in a variable somewhere for use with
echo ${password_salted_sha512_hash} | pw -V ${IMAGE_CHROOT_DIR}/etc usermod -n\
${username} -H 0
Thanks,
oh
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