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Overview
Courier-IMAP is a IMAP server that uses
Maildirs. Please note that this IMAP server does NOT handle traditional mailbox
files (/var/spool/mail, and derivatives), it was written
and optimized for the specific purpose of providing IMAP access to Maildirs.
«Maildir» is a
directory-based mail storage format originally introduced in the Qmail mail server, and
adopted as an alternative mail storage format by both Exim and Postfix.
Courier-IMAP is popular on Postfix sites that are configured to use maildirs. The primary
advantage of maildirs is that multiple applications can access the same Maildir
simultaneously without requiring any kind of locking whatsoever. Maildir is a faster and
more efficient way to store mail.
Authentication is done with the Courier authentication library. The
authentication library is a separate, standalone package. This authentication library
must now be installed, separately.
Installalling the Authentication Library
Download from: http://www.courier-mta.org/download.php#authlib
The Courier authentication library provides different implementations
of authentication:
-
Use the traditional system password files: /etc/passwd and /etc/shadow,
possibly in conjunction with the PAM library.
-
Maintain all this information in a GDBM or a DB database. The GDBM
or the DB database is compiled from plain text files. Perl scripts provide a simple
interface for creating and editing the authentication information, then a script
compiles the plain text files into a database.
-
Use an LDAP server for authentication.
-
Use a table in a MySQL database for authentication
-
Use a table in a PostgreSQL database for authentication
All Courier components that use this authentication library, therefore,
will be able to authenticate E-mail accounts using any of the above methods.
Please be careful about courier. If you do any step which begins with
"courier>" with the root user, installation fails. Only use root when you see
"root>" sign.
If you use redhat or any derivative of it, you have to add "--with-redhat" option to the configure step above.
root> groupadd -g 500 courier
root> useradd -u 500 -g 500 -c "Courier IMAP" -d /home/courier -s
/sbin/nologin
courier> gunzip
courier-authlib-0.59.2.tar.gz
courier> tar xvf courier-authlib-0.59.2.tar
courier> cd courier-authlib-0.59.2
courier> ./configure --with-mailuser=mail \
--with-mailgroup=mail \
--with-redhat \
--with-authshadow
courier> make
root> make install
root> make install-configure
- /usr/local/etc/authlib - the configuration
files.
- /usr/local/sbin - the authdaemond startup
script; several utility programs
(courierlogger, authconfig, authtest, authenumerate); and userdb scripts.
- /usr/local/lib/courier-authlib - various
authentication modules, as shared libraries.
- /usr/local/libexec/courier-authlib - some
miscellaneous stuff.
- /usr/local/var/authdaemon - a subdirectory that
contains the filesystem
socket which authdaemond listens on.
- /usr/local/include - a header file that Courier
packages will use to build against courier-authlib.
/usr/local/etc/authlib/authdaemonrc
authmodulelist="authpam authshadow"
daemons=5
DEBUG_LOGIN=0
Use the following Startup / Shutdown Script in /etc/init.d (for Redhat)
#!/bin/sh
# Akadia AG, Fichtenweg 10, CH-3672 Oberdiessbach
# --------------------------------------------------------------------------
# File: courier-authlib
#
# Autor: Martin Zahn, Akadia AG, 15.04.2007
#
# Purpose: Startup script for the Courier Authlib Daemon
#
# Location: /etc/init.d
#
--------------------------------------------------------------------------
# chkconfig: 2345 65 35
# description: Start / Stop Courier Authlib Daemon
# processname: authdaemond
# Source function library.
.
/etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
RETVAL=0
start() {
# Start daemons.
echo -n "Starting Courier-IMAP Authlib Daemon: "
/usr/local/sbin/authdaemond start 2>/dev/null 1>&2 && success ||
failure
RETVAL=$?
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/courier-authdaemond
echo
return $RETVAL
}
stop() {
# Stop
daemons.
echo -n "Shutting down Courier-IMAP Authlib Daemon: "
/usr/local/sbin/authdaemond stop 2>/dev/null 1>&2 && success ||
failure
RETVAL=$?
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/courier-authdaemond
echo
return $RETVAL
}
restart() {
stop
start
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
restart
;;
*)
echo "Usage: authdaemond {start|stop|restart}"
exit 1
esac
exit $?
Installalling Courier IMAP
Download from: http://www.courier-mta.org/download.php#imap
Please be careful about courier. If you do any step which begins with
"courier>" with the root user, installation fails. Only use root when you see
"root>" sign.
If you use redhat or any derivative of it, you have to add "--with-redhat" option to the configure step above.
root> groupadd -g 500 courier
root> useradd -u 500 -g 500 -c "Courier IMAP" -d /home/courier -s
/sbin/nologin
courier> gunzip
courier-imap-4.1.2.tar.gz
courier> tar xvf courier-imap-4.1.2.tar
courier> cd courier-imap-4.1.2
courier> ./configure --with-redhat \
--enable-workarounds-for-imap-client-bugs \
--with-authchangepwdir \
--enable-unicode \
--with-trashquota
courier> make
root> make install
root> make install-configure
- /usr/lib/courier-imap/etc - the configuration
files.
- /usr/lib/courier-imap/bin - the imapd
daemon.
- If the directory
/etc/pam.d exists, make install creates
/etc/pam.d/imap and /etc/pam.d/pop3, overwriting any
existing files. If you have some other IMAP server installed, this means that you will
want to save your existing configuration in /etc/pam.d/{imap|pop3}.
/usr/lib/courier-imap/etc/imapd
MAXDAEMONS=1000
MAXPERIP=200
MAILDIRPATH=Maildir
MAILDIR=Maildir
The /usr/lib/courier-imap/etc/imapd-ssl configuration file sets some
additional options for SSL support, which you may need to adjust. Consult that
configuration file for additional information. Then, you also have to run the
/usr/lib/courier-imap/libexec/imapd-ssl.rc script from your system startup
and shutdown scripts, just like the /usr/lib/courier-imap/libexec/imapd.rc
script. You may accept both SSL and non-SSL connections by running both scripts.
Note that SSL requires a valid, signed, X.509 certificate to be installed where
Courier-IMAP expects to find it. The default location for the X.509 certificate, in PEM
format, is /usr/lib/courier-imap/share/imapd.pem. The X.509 certificate must
be signed by a certificate authority that is known to the IMAP client. You can generate
your own self-signed certificate by running the script
/usr/lib/courier-imap/share/mkimapdcert which will work too, except that
IMAP clients using SSL will display a warning message the first time they connect to the
server. To get rid of the warning message you'll have to pay for a signed X.509
certificate. The gory details of setting up SSL is beyond the scope of this document, and
you should consult the OpenSSL documentation for more information.
The mkimapdcert script will not overwrite an existing
imapd.pem certificate, in order to allow precompiled packages to simply call
mkimapdcert after installation, without worry.
cd /usr/lib/courier-imap/share
./mkimapdcert
./mkdhparams
Use the following Startup / Shutdown Script in /etc/init.d (for Redhat)
#!/bin/sh
# Akadia AG, Fichtenweg 10, CH-3672 Oberdiessbach
# --------------------------------------------------------------------------
# File: courier-imapd
#
# Autor: Martin Zahn, Akadia AG, 14.04.2007
#
# Purpose: Startup script for the Courier IMAP Daemon
#
# Location: /etc/init.d
# --------------------------------------------------------------------------
# chkconfig: 2345 66 34
# description: Start / Stop Courier IMAP Daemon
# processname: authdaemond
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ ${NETWORKING} = "no" ] && exit 0
RETVAL=0
start() {
# Start daemons.
echo -n "Starting Courier-IMAP: "
/usr/lib/courier-imap/libexec/imapd.rc start 2>/dev/null 1>&2 &&
success || failure
RETVAL=$?
[ $RETVAL -eq 0 ] && touch /var/lock/subsys/courier-imapd
echo
return $RETVAL
}
stop() {
# Stop
daemons.
echo -n "Shutting down Courier-IMAP: "
/usr/lib/courier-imap/libexec/imapd.rc stop 2>/dev/null 1>&2 &&
success || failure
RETVAL=$?
[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/courier-imapd
echo
return $RETVAL
}
restart() {
stop
start
}
# See how we were called.
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
restart
;;
*)
echo "Usage: authdaemond {start|stop|restart}"
exit 1
esac
exit $?
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