Upgrading Dovecot v2.2 to v2.3
==============================

Downgrading is possible to v2.2.27 and later. (v2.2.27 accidentally broke
dovecot.index* backwards compatibility a bit.)

Settings changes
----------------

 * 'director_doveadm_port' setting removed. Name the 'inet_listener doveadm {
   .. }' instead.
 * 'mdbox_purge_preserve_alt' setting removed. It's always assumed to be "yes"
   now.
 * 'director_consistent_hashing' setting removed. It's always assumed to be
   "yes" now.
 * 'recipient_delimiters' setting used to be treated as a separator string. Now
   it's instead treated as a list of alternative delimiter characters.
 * Time interval based settings no longer default to "seconds". All numbers
   must explicitly be followed by the time unit (except 0). This is important,
   because some settings now support milliseconds as well.
 * fs-posix: prefix=path parameter no longer automatically appends '/' to the
   path if it's not there. This allows using it properly as a prefix, instead
   of only a directory prefix. Make sure you have the '/' appended to the
   prefix, or the "dir/filename" will be accessed just as "dirnamename".
 * 'ssl_protocols' setting was replaced by 'ssl_min_protocol'. Now you only
   specify the minimum ssl protocol version Dovecot accepts, defaulting to
   TLSv1.

Statistics redesign
-------------------

The statistics code was redesigned. The old "stats" plugin was renamed to
"old_stats" and the "doveadm stats" was renamed to "doveadm oldstats". There's
a new "doveadm stats" command that isn't compatible with the old one. Also the
new stats code doesn't require a plugin, so make sure you remove 'stats' from
'mail_plugin' setting. For more details see <Statistics.txt>.

So if you wish to keep using the old stats:

 * 'mail_plugins = stats' -> 'mail_plugins = old_stats'
 * 'service stats' -> 'service old-stats'
    * 'executable = stats' -> 'executable = old-stats'
    * 'fifo_listener stats-mail' -> 'fifo_listener old-stats-mail'
    * 'fifo_listener stats-user' -> 'fifo_listener old-stats-user'
    * 'unix_listener stats' -> 'unix_listener old-stats'
 * 'plugin { stats_refresh }' -> 'plugin { old_stats_refresh }'
 * 'plugin { stats_notify_path }' -> 'plugin { old_stats_notify_path }'
 * 'plugin { stats_track_cmds }' -> 'plugin { old_stats_track_cmds }'
 * 'auth_stats' -> keep as 'auth_stats'
 * 'stats_*' settings -> 'old_stats_*'

Localhost auth penalty
----------------------

Dovecot no longer disables auth penalty waits for clients connecting from
localhost (or login_trusted_networks in general). The previous idea was that it
would likely be a webmail that would have its own delays, but there are no
guarantees about this.

If the old behavior is still wanted, it's possible to do nowadays even more
generically with e.g.:

---%<-------------------------------------------------------------------------
passdb {
 driver = passwd-file
 args = username_format=%{rip} /etc/dovecot/passdb
}
---%<-------------------------------------------------------------------------

/etc/dovecot/passdb:

---%<-------------------------------------------------------------------------
127.0.0.1:::::::nodelay=yes
192.168.10.124:::::::nodelay=yes
---%<-------------------------------------------------------------------------

Setting default changes
-----------------------

 * mdbox_rotate_size=2M -> 10M
 * mailbox_list_index=no -> yes
 * imap_logout_format=in=%i out=%o
    * -> in=%i out=%o deleted=%{deleted} expunged=%{expunged}
      trashed=%{trashed} hdr_count=%{fetch_hdr_count}
      hdr_bytes=%{fetch_hdr_bytes} body_count=%{fetch_body_count}
      body_bytes=%{fetch_body_bytes}
 * ssl_cipher_list=ALL:!LOW:!SSLv2:!EXP:!aNULL
    * ->
      ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
 * mail_log_prefix="%s(%u): "
    * -> "%s(%u)<%{pid}><%{session}>: "
 * mysql: ssl_verify_server_cert=no -> yes
 * 'ssl_options': 'no_compression' is now the default, and a new 'compression'
   option is introduced for enabling compression

Diffie-Hellman parameters for SSL
---------------------------------

 * ssl-parameters.dat file is now obsolete. You should use ssl_dh setting
   instead:'ssl_dh=</etc/dovecot/dh.pem'
    * You can convert an existing ssl-parameters.dat to dh.pem:

      ---%<-------------------------------------------------------------------
      dd if=/var/lib/dovecot/ssl-parameters.dat bs=1 skip=88 | openssl dh
      -inform der > /etc/dovecot/dh.pem
      ---%<-------------------------------------------------------------------

Other changes
-------------

 * Linux: Dovecot no longer enables core dumping for "setuid processes", which
   most of them are.
    * To enable them with Linux kernel v3.6+: Make sure core dumps get written
      to a globally shared directory and enable them with:'sysctl -w
      fs.suid_dumpable=2'
       * With older Linux kernel versions you can set it to 1, but that's not
         good for security of your system.
    * You can also revert to old behavior with: 'import_environment =
      $import_environment PR_SET_DUMPABLE'
       * However, this also may have some security implications depending on
         the setup. Mainly if you have system users and you've enabled
         chrooting or mail_access_groups, this could allow the system users to
         gain unintentional access.
 * userdb nss was removed. Use userdb passwd instead.
 * doveadm: table formatter prints the header now to stdout, not stderr
 * doveadm: Removed mount commands
 * OpenSSL version is required to be at least 1.0.1 for Dovecot to build
 * subscriptions file is written in a new version 2 format. Dovecot v2.2.17 and
   newer can read this file.
 * mail_log plugin: Headers are logged as UTF-8 (instead of MIME-encoded)
 * auth: When iterating users in userdb passwd, skip users that aren't in the
   first/last_valid_gid range
 * auth protocol has changed some error fields:
    * temp -> code=temp_fail
    * authz -> code=authz_fail
    * user_disabled -> code=user_disabled
    * pass_expired -> code=pass_expired

(This file was created from the wiki on 2017-12-22 04:42)
