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<TITLE>Installing and configuring the IMAP Server
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<h1>Installing and configuring the IMAP Server
</h1>
<body>
This section describes the shell scripts to run and the configuration
files to modify once "<tt>configure</tt>" and "<tt>make</tt>" have run.
<ol> <li>Create a user and group for the Cyrus subsystem. The
examples in this document assume a user of "<tt>cyrus</tt>" and a
group of "<tt>mail</tt>", though any user and group name can be used.
If a user other than "<tt>cyrus</tt>" is to be used, it must have been
previously specified in the "<TT>--with-cyrus-user=</TT>" option to
"<TT>configure</TT>". If a group other than "<tt>mail</tt>" is to be
used, it must have been previously specified in the
"<TT>--with-cyrus-group=</TT>" option to "<TT>configure</TT>".
<P>
<li>After you've logged in as "<TT>root</TT>", install the cyrus software.
<pre>
<kbd> make install
</kbd></pre>
Be sure that the server programs ended up in the directory specified
by "<tt>--with-cyrus-prefix</tt>" (by default, "<tt>/usr/cyrus/bin</tt>").
<p><li>The Cyrus IMAP server uses the 4.3BSD syslog that separates
messages into both levels and categories. Invoke "<kbd>man
syslog</kbd>" to see if "<tt>openlog()</tt>" takes three arguments. If
it does not, replace the system "<tt>syslogd</tt>" and
"<tt>syslog.conf</tt>" with the files provided in the
"<tt>syslog</tt>" directory.
<pre>
<kbd> mv syslogd /etc/syslogd
mv syslog.conf /etc/syslog.conf
</kbd></pre>
If you do not copy the "<tt>syslog/syslog.conf</tt>" file to the
"<tt>/etc</tt>" directory, be sure to add support for
"<tt>local6.debug</tt>". The file should include a line like:
<pre>
local6.debug /var/log/imapd.log
</pre>
You probably also want to log SASL messages with a line like:
<pre>
auth.debug /var/log/auth.log
</pre>
After installation and testing, you probably want to change the
".debug" component to something a little less verbose. Create the log
files:
<pre>
<kbd> touch /var/log/imapd.log /var/log/auth.log
</kbd></pre>
<li>Create the file "<tt>/etc/imapd.conf</tt>". Here is a sample
"<tt>imapd.conf</tt>" with a minimal number of values defined:
<pre>
configdirectory: /var/imap
partition-default: /var/spool/imap
admins: curtj abell
sasl_pwcheck_method: saslauthd
</pre>
For a description of all the fields in this file, see the
<tt>imapd.conf(5)</tt> man page. (Note
that this file also exports values to libsasl, the most important of
them the <tt>pwcheck_method</tt>. In this example, users are
authenticated via the <tt>saslauthd</tt> daemon, which can be run
in a number of different ways.)
<p><b>READ THE <tt>imapd.conf(5)</tt> MAN PAGE</b>. There are options
in there that you will want to know about and default behavior that
you may not like.
<P>
Note that <b>everyday users should not be administrators</b>. Admins
have powers not granted to regular users and while the server allows
them to receive mail, some problems will occur if admins are used as
regular users. You also should <b>not</b> read mail as an
administrator. You should have separate accounts for reading mail and
administrating. This is especially true if using the
<tt>altnamespace</tt> option, because admins are <b>always</b>
presented with the standard (internal) namespace.
<p><li>Create the configuration directory specified by the
"<tt>configdirectory</tt>" option in "<tt>imapd.conf.</tt>" The
configuration directory is similar in concept to the
"<tt>/usr/lib/news</tt>" directory. It stores information about the
IMAP server as a whole.
<p>This document uses the configuration directory "<tt>/var/imap</tt>"
in its examples. This directory should be owned by the
cyrus user and group and should not permit access to other users.
<pre>
<kbd> cd /var
mkdir imap
chown cyrus imap
chgrp mail imap
chmod 750 imap
</kbd></pre>
<li>Create the default partition directories specified in the
"<tt>/etc/imapd.conf</tt>" file.
<p>This document uses a default partition directory of
"<tt>/var/spool/imap</tt>" in the following example:
<pre>
<kbd> cd /var/spool
mkdir imap
chown cyrus imap
chgrp mail imap
chmod 750 imap
</kbd></pre>
The partition directory is similar in concept to
<tt>/var/spool/news</tt>. It is where the mailboxes are stored.
Unlike most netnews systems, Cyrus allows you to have more
than one partition.
<li>If you wish to use Sieve, and you didn't configure deliver to look
in home directories (see the <tt>imapd.conf</tt> man page), create the
Sieve directory:
<pre>
<kbd> cd /usr
mkdir sieve
chown cyrus sieve
chgrp mail sieve
chmod 750 sieve
</kbd></pre>
<li>Change to the Cyrus user and use the tool
"<tt>tools/mkimap</tt>" to create the rest of the directories
(subdirectories of the directories you just created).
<pre>
<kbd> su cyrus
tools/mkimap
exit
</kbd>
</pre>
If Perl is not available, it should be easy (but time consuming) to
create these directories by hand. <P>
<li><b>LINUX SYSTEMS USING EXT2FS ONLY</b>: Set the user, quota, and
partition directories to update synchronously. Failure to do this may
lead to data corruption and/or loss of mail after a system
crash. Unfortunately, doing so may result in a serious performance
hit. If you are using a newer filesystem than ext2fs on Linux, this
step should not be necessary. (Running ext3 in any mode is safe.)
<pre>
<kbd> cd /var/imap
chattr +S user quota user/* quota/*
chattr +S /var/spool/imap /var/spool/imap/*
</kbd></pre>
Also set the queue directory of the mail daemon to update
synchronously. The following example is for sendmail:
<pre>
<kbd> chattr +S /var/spool/mqueue
</kbd></pre>
<p><li>To enable STARTTLS support, see <a href="#openssl">how to
configure OpenSSL</a> below.
<p><li>Add the following lines to the "<tt>/etc/services</tt>" file if they
aren't already there.
<pre>
pop3 110/tcp
nntp 119/tcp
imap 143/tcp
imsp 406/tcp
nntps 563/tcp
acap 674/tcp
imaps 993/tcp
pop3s 995/tcp
kpop 1109/tcp
sieve 2000/tcp
lmtp 2003/tcp
fud 4201/udp
</pre>
<p><li><b>Remove "<tt>/etc/[x]inetd.conf</tt>" entries.</b> Any
<tt>imap</tt>, <tt>imaps</tt>, <tt>pop3</tt>, <tt>pop3s</tt>,
<tt>kpop</tt>, <tt>lmtp</tt> and <tt>sieve</tt> lines need to be
removed from <tt>/etc/[x]inetd.conf</tt> and [x]inetd needs to be
restarted.
</ol>
<a name="master"><h3>Configuring the Master Process</h3></a>
<ol>
<li> Choose a configuration from the <tt>master/conf</tt> directory:
<dl compact>
<dt><tt>small.conf</tt><dd>bare-bones server supporting IMAP and POP
<dt><tt>normal.conf</tt><dd>server supporting IMAP, POP, the SSL
wrapped versions, and the Sieve script management protocol
<dt><tt>prefork.conf</tt><dd>The same configuration as above, but
with some preforked processes for faster processing.
<dt><tt>backend-cmu.conf</tt><dd>Our configuration (for Murder Backend /
typical IMAP servers)
<dt><tt>frontend-cmu.conf</tt><dd>Our configuration (for Murder Frontend servers)
</dl>
<p>To use <tt>normal.conf</tt>, do:
<pre>
<kbd> cp master/conf/normal.conf /etc/cyrus.conf
</kbd></pre>
<p>Optionally, you can edit <tt>/etc/cyrus.conf</tt> to disable or
enabling certain services, or to tune the number of preforked copies.
Be sure not to remove the entries that are labeled required.
<p><li>Arrange to start "<tt>/usr/cyrus/bin/master</tt>" as root when
the system starts. It will bind some ports and then give up it's root
privileges. Until your system reboots, you can start the master
process by hand:
<pre>
<kbd> /usr/cyrus/bin/master &
</kbd></pre>
<p><li>Monitor the progress of the master process by examining the
<tt>imapd.log</tt> file. It should never exit by itself, but you can
shut down the mail system by sending it a signal with <tt>kill</tt>.
</ol>
<a name="mta"><h3>Configuring the Mail Transfer Agent</h3></a>
<p>In order to deliver mail to the Cyrus system, you'll have to
configure your MTA (Sendmail, Postfix, Exim, etc) to use LMTP.
<h4>Configuring <a href="http://www.sendmail.org/">Sendmail</a></h4>
Generate a sendmail configuration file which delivers local mail
to the IMAP server. See the file <TT>cf/README</TT> in the Sendmail
distribution for information on how to create a complete configuration
file. This file also lists variables that can be used to customize
the mailer definitions mentioned below.
<p>The following configurations assume that you are using the
<tt>lmtpunix</tt> service from one of the sample <tt>cyrus.conf</tt>
files discussed above.
<ul>
<li> For Sendmail 8.12.4 and higher, use the <tt>cyrusv2</tt> mailer
definition in the Sendmail distribution:
<pre>
define(`confLOCAL_MAILER', `cyrusv2')
MAILER(`cyrusv2')
</pre>
If you wish to change the name of the UNIX socket or switch to TCP,
define <tt>CYRUSV2_MAILER_ARGS</tt> appropriately as described in
<TT>cf/README</TT>.</li>
<p><li> For Sendmail 8.10 - 8.12.3, use the <a
href="cyrusv2.mc">cyrusv2.mc</a> file as a template to create a
Sendmail configuration file.</li>
<p><li> For Sendmail 8.9.x and earlier, use the <tt>cyrus</tt> mailer
definition in the Sendmail distribution:
<pre>
define(`confLOCAL_MAILER', `cyrus')
MAILER(`cyrus')
</pre>
Edit <TT>/etc/group</TT> and
add user "<TT>daemon</TT>" to the "<TT>mail</TT>" group. This will
permit sendmail to run the "<TT>deliver</TT>" (LMTP client) program to
deliver mail to the IMAP server.</li>
</ul>
<p>Cyrus also includes a socket map daemon <tt>smmapd</tt> which can
be used by Sendmail 8.13 and higher (a patch for 8.12 is available) to
verify at RCPT TO time that a message can be delivered to the
particular mailbox. To use this daemon, add <tt>smmapd</tt> as a
service in <tt>cyrus.conf</tt> and configure Sendmail accordingly.
<h4>Configuring <a href="http://www.postfix.org/">Postfix</a></h4>
The Postfix source distribution comes with the
file "<tt>README_FILES/LMTP_README</tt>". Even if you are using a
binary distribution of Postfix, it would be well worth your while
to download the full Postfix source. Not only will you get the
above file, but numerous other "readme" files and sample
configuration files.
<p>One thing you need to watch out for is the UID and GID of
the Postfix software. As it states in the Postfix "<tt>INSTALL</tt>"
document, you must create a new account that does not share its UID
and GID with any other user account. This is for security reasons.
If you installed Postfix with a GID of "<tt>mail</tt>", you will need
to select a different GID for Cyrus. See the Cyrus configure options
"<tt>--with-cyrus-user</tt>" and "<tt>--with-cyrus-group</tt>". (This
was more crucial when the use of Cyrus' "<tt>deliver</tt>" was more
prevalent, but it is still a good idea to follow this policy.)
<p>Another thing to note is the location of your "<tt>sendmail</tt>"
command. On some platforms this will be "<tt>/usr/sbin/sendmail</tt>",
on others, "<tt>/usr/lib/sendmail</tt>". Cyrus will need to know where
this command is. See <a href="install-sieve.html">Installing Sieve</a>
for more details.
<p>Assuming that you are using the <tt>lmtpunix</tt> service from one
of the sample <tt>cyrus.conf</tt> files discussed above, the Postfix
configuration file "<tt>/etc/postfix/main.cf</tt>" should have the
following line:
<pre>
mailbox_transport = lmtp:unix:/var/imap/socket/lmtp
</pre>
<p>Naturally, both the Postfix UID and the Cyrus UID need to be
able to access the specified socket file.
<p>Starting with Postfix snapshot-20010222, you can improve the
efficiency of LMTP delivery via the "<tt>mailbox_transport</tt>" by
putting the following entries in "<tt>/etc/postfix/main.cf</tt>":
<pre>
local_destination_recipient_limit = 300
local_destination_concurrency_limit = 5
</pre>
<p>Of course you should adjust these settings as appropriate for
the capacity of the hardware you are using. The recipient limit
setting can be used to take advantage of the single instance
message store capability of Cyrus. The concurrency limit can be
used to control how many simultaneous LMTP sessions will be
permitted to the Cyrus message store.
<p>Additional examples are included in the Postfix
file "<tt>README_FILES/LMTP_README</tt>".
<h4>Configuring <a href="http://www.exim.org/">Exim 4</a></h4>
Generate an Exim configuration file which delivers local mail to the
IMAP server. See the Exim documentation for information on how to
create a complete configuration file.
<p>Cyrus is designed to be used as a black-box server -- there
are usually no local user accounts. As a result, you must define the
following "router":
<ul>
<pre>
localuser:
driver = accept
transport = local_delivery
</pre>
</ul>
<p>The following "transports" assume that you are using either the
<tt>lmtpunix</tt> or <tt>lmtp</tt> service from one of the sample
<tt>cyrus.conf</tt> files discussed above.
<ul>
<p><li> Using <tt>lmtpunix</tt> (UNIX socket):
<pre>
local_delivery:
driver = lmtp
command = "/usr/cyrus/bin/deliver -l"
batch_max = 20
user = cyrus
</pre>
</li>
<p><li> Using <tt>lmtp</tt> (TCP socket -- Exim and Cyrus on same host):
<pre>
local_delivery:
driver = smtp
protocol = lmtp
hosts = localhost
allow_localhost
</pre>
</li>
</ul>
<p>For more advanced configurations (such as address verification, etc),
consult the Exim documentation and sample configurations.
<h3>Exporting Netnews via IMAP</h3>
If you wish to use export Netnews via IMAP, consult <a
href=install-netnews.html>install-netnews.html</a>.
<a name="openssl"><h2>SSL, TLS, and OpenSSL</h2></a>
<p>Transport Layer Security (TLS), is a standardized version of the Secure
Sockets Layer (SSL v3) standard. IMAP can make use of two different
versions of TLS/SSL: STARTTLS and an SSL wrapped session.</p>
<p>In STARTTLS, a client connects to the IMAP port as normal and then
issues the STARTTLS command, which begins a TLS negotiation. This is
currently supported by the Cyrus IMAP server when it is compiled with
OpenSSL.</p>
<p>The alternative, a SSL wrapped connection, involves the client
connected to a seperate port ("<tt>imaps</tt>") and negotiating a SSL
session before starting the IMAP protocol. Again, this is supported
natively by the Cyrus IMAP server when it is compiled with
OpenSSL.</p>
<p>Both TLS and SSL require a server key and a certificate.
Optionally, in addition to establishing a secure connection, TLS can
authenticate the client.</p>
<h3>Configuring Cyrus with OpenSSL</h3>
<ol>
<li><p>OpenSSL requires the certificate and key in PEM format. You can
create the server's private key and certificate yourself using
OpenSSL. Here, we create a self-signed key for the machine
"<tt> foobar.andrew.cmu.edu</tt>" and put both the certificate and key
in the file "<tt>/var/imap/server.pem</tt>".</p>
<p>Please do not blindly enter in the information to OpenSSL
below. Instead, enter the appropriate information for your
organization (i.e. NOT Carnegie Mellon University for the Organization
name, etc.).</p>
<pre>
<kbd>openssl req -new -x509 -nodes -out /var/imap/server.pem -keyout /var/imap/server.pem -days 365</kbd>
Using configuration from /usr/local/lib/openssl/openssl.cnf
Generating a 1024 bit RSA private key
.............+++++
......................+++++
writing new private key to '/var/imap/server.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]:<kbd>US</kbd>
State or Province Name (full name) [Some-State]:<kbd>Pennsylvania</kbd>
Locality Name (eg, city) []:<kbd>Pittsburgh</kbd>
Organization Name (eg, company) [Internet Widgits Pty Ltd]:<kbd>Carnegie Mellon University</kbd>
Organizational Unit Name (eg, section) []:<kbd>Andrew Systems Group</kbd>
Common Name (eg, YOUR name) []:<kbd>foobar.andrew.cmu.edu</kbd>
Email Address []:
</pre></li>
<li>Make sure to make key file(s) readable by the Cyrus user. For
example: <kbd>chown cyrus /var/imap/server.pem</kbd>
<li>Add the following to <tt>/etc/imapd.conf</tt> to tell the server
where to find the certificate and key file (used for ALL services):
<pre>tls_cert_file: /var/imap/server.pem
tls_key_file: /var/imap/server.pem
</pre>
Optionally, you can use separate certificates and key files for each
service:
<pre>[servicename]_tls_cert_file: /var/imap/imap-server.pem
[servicename]_tls_key_file: /var/imap/imap-server.pem
</pre>
"servicename" here refers to the name of the service as specified
in cyrus.conf. It is <i>not</i> necessaraly the name of the binary.
<p>This is useful if you want to use different hostnames for each service
(e.g. via virtual host interfaces or DNS CNAMEs). In the absence of
any of the service specific options, the value of the global option is
used. A value of <b>disabled</b> for the certificate or key file for
a particular service will disable SSL/TLS for that service.
<p>If you have a Certificate Authority (CA), you may wish to generate
a certificate request and send it to be signed by your CA.
<p>By default, Cyrus will cache SSL/TLS sessions for reuse for up to
24 hours. By adjusting the value of the <tt>tls_session_timeout</tt> option in
<tt>imapd.conf</tt>, the session caching can be disabled (0) or the
expiration period shortened.
<p>
</li>
<li>You can test STARTTLS by using <tt>imtest</tt>:
<pre><kbd>imtest -t "" foobar.andrew.cmu.edu
</kbd></pre>
</ol>
<h3>Client-side certificates</h3>
<p>Client certificates are somewhat harder to configure than server
certificates. You'll need a CA (certificate authority) and need to
generate client certificates signed by that CA. STARTTLS in Sendmail
and other MTAs have similiar problems, so <a
href="http://www.sendmail.org/~ca/email/starttls.html">Claus Assman's
page</a> is a good reference.</p>
<p>You can use the self-signed certificate generated above as a CA for
client certificates. To do this, try the following:</p>
<p><b>TODO:</b> write me!</p>
<p>Unfortunately, there's no standard on how to convert the client's
authenticate DN (distinguished name) to a SASL authentication
name.</p>
<a name="altnamespace"><h2>Alternate Namespace and UNIX Hierarchy
Convention</h2></a>
If you wish to use the alternate namespace and/or the UNIX hierarchy
convention, consult <a
href=altnamespace.html#altnameconfig>altnamespace.html</a>.
<P><HR>
last modified: $Date: 2006/11/30 17:11:16 $
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