Rootless Installation
=====================

It's possible to make Dovecot run under a single system user without requiring
root privileges at any point. This shouldn't be thought of as a security
feature, but instead simply as a way for non-admins to run Dovecot in their
favorite mail server. It's also useful if you just wish to test Dovecot without
messing up your system.

If you think of this as a good way to achieve security, ask yourself which is
worse:

a)

 * A very small possibility to get root privileges through Dovecot.
 * A small possibility without logging in to get into system as a
   non-privileged *dovecot* user, chrooted into an empty directory.
 * A small possibility to get user's privileges after logging in, but no
   possibility to read others' mails since they're saved with different UIDs
   (plus you might also be chrooted to your own mailbox).

b)

 * Absolutely zero possibility to get root privileges through Dovecot.
 * A small possibility to get into system as a mail user, possibly even without
   logging in, and being able to read everyone's mail (and finally gaining
   roots by exploiting some just discovered local vulnerability, unless you
   bothered to set up a special chrooted environment).

Installation
------------

Install somewhere under home directory:

---%<-------------------------------------------------------------------------
./configure --prefix=$HOME/dovecot
make
make install
---%<-------------------------------------------------------------------------

Dovecot is then started by running '~/dovecot/sbin/dovecot'. The configuration
file exists in '~/dovecot/etc/dovecot.conf'.

Configuration
-------------

The important settings to change for rootless installation are:

 * 'login_chroot=no'
 * 'login_user' and auth 'user' should be the username you're running Dovecot
   as.
 * 'log_path' and 'info_log_path'
 * Instead of <passdb PAM> [PasswordDatabase.PAM.txt] use for example
   <passwd-file> [AuthDatabase.PasswdFile.txt].
 * 'listen' and 'ssl_listen' ports need to be changed

Example configuration for user called *testuser*:

---%<-------------------------------------------------------------------------
protocols = imap imaps pop3 pop3s
ssl_disable = yes
disable_plaintext_auth = no
pop3_uidl_format = %08Xu%08Xv

login_chroot = no
login_user = testuser

# paths
log_path = /home/testuser/dovecot/error.log
info_log_path = /home/testuser/dovecot/info.log
mail_location = maildir:~/Maildir

# ports
protocol imap {
  listen = *:14300
  ssl_listen = *:14301
}
protocol pop3 {
 listen = *:11000
  ssl_listen = *:11001
}

# authentication
auth default {
  mechanisms = plain
  user = testuser
  passdb passwd-file {
    args = /home/testuser/dovecot/passwd
  }
  userdb passwd {
  }
}
---%<-------------------------------------------------------------------------

'/home/testuser/dovecot/passwd' contains the password:

---%<-------------------------------------------------------------------------
testuser:{PLAIN}testpass
---%<-------------------------------------------------------------------------

You should now be able to log in as *testuser* using password *testpass*.

(This file was created from the wiki on 2011-05-11 04:42)
