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Date:      Mon, 15 May 2006 05:22:59 +0200
From:      albi <albi@scii.nl>
To:        Philip Hallstrom <freebsd@philip.pjkh.com>
Cc:        wmoran@collaborativefusion.com, freebsd-questions@freebsd.org, andrew.chace@gmail.com
Subject:   Re: VM and jailed processes
Message-ID:  <20060515052259.38ff3ba7.albi@scii.nl>
In-Reply-To: <20060514221324.L69900@bravo.pjkh.com>
References:  <1147578337.10075.12.camel@LatitudeFC5.network> <20060514100121.60fce840.wmoran@collaborativefusion.com> <1147630193.10075.33.camel@LatitudeFC5.network> <20060514221324.L69900@bravo.pjkh.com>

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On Sun, 14 May 2006 22:14:31 -0500 (CDT)
Philip Hallstrom <freebsd@philip.pjkh.com> wrote:

> > I'm thinking of using mount_nullfs(8) to provide read-only mounts
> > for all the executables in each jail. I've been doing some reading,
> > 'man rtld(1)', and it seems that the linker will take of sharing
> > non-writable code between processes, even if the executables are
> > loaded from different mount-points/file-systems.
> 
> You should also look at ezjail...  it uses the same tricks to reduce
> the size of individual jail systems.  I haven't used it, but keep
> meaning too (next server :)
> 
> http://erdgeist.org/arts/software/ezjail/

i haven't tried ezjail, but i'm using read-only nullfs mounts with
jails for more than a year on 2 different mail-servers (surprising how
one own original ideas appear not to be original after a while :)

you should perhaps realise that it's not all that easy, e.g. software
like : postfix, mailman, dovecot or any other smtp or imap/pop3-server
software probably needs 1 special user-account or more to be able to
run, also e.g. postfix and squirrelmail need files in /var/spool/

some software, like postfixadmin, provides a setup-script which refuses
to correctly detect which software is installed (it however runs fine
with most of /usr/local/ directories mounted with nullfs
mounted read-only from a build-jail)

also, you will need to copy /usr/local/etc/ files/dirs when needed

in other words, it's very interesting, but beware of the amount of work
it *might* involve

-- 
grtjs, albi
gpg-key: lynx -dump http://scii.nl/~albi/gpg.asc | gpg --import



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