11 Postfix With SMTP-AUTH And TLS

11 Postfix With SMTP-AUTH And TLS

In order to install Postfix with SMTP-AUTH and TLS do the following steps:

apt-get install postfix libsasl2 sasl2-bin libsasl2-modules libdb3-util procmail

You will be asked two questions. Answer as follows:

General type of configuration? <-- Internet Site
Mail name? <-- server1.example.com

Then run

dpkg-reconfigure postfix

Again, you'll be asked some questions:

General type of configuration? <-- Internet Site
Where should mail for root go <-- NONE
Mail name? <-- server1.example.com
Other destinations to accept mail for? (blank for none) <-- server1.example.com, localhost.example.com, localhost
Force synchronous updates on mail queue? <-- No
Local networks? <-- 127.0.0.0/8
Use procmail for local delivery? <-- Yes
Mailbox size limit <-- 0
Local address extension character? <-- +
Internet protocols to use? <-- all

Next, do this:

postconf -e 'smtpd_sasl_local_domain ='
postconf -e 'smtpd_sasl_auth_enable = yes'
postconf -e 'smtpd_sasl_security_options = noanonymous'
postconf -e 'broken_sasl_auth_clients = yes'
postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination'
postconf -e 'inet_interfaces = all'
echo 'pwcheck_method: saslauthd' >> /etc/postfix/sasl/smtpd.conf
echo 'mech_list: plain login' >> /etc/postfix/sasl/smtpd.conf

Afterwards we create the certificates for TLS:

mkdir /etc/postfix/ssl
cd /etc/postfix/ssl/
openssl genrsa -des3 -rand /etc/hosts -out smtpd.key 1024
chmod 600 smtpd.key
openssl req -new -key smtpd.key -out smtpd.csr
openssl x509 -req -days 3650 -in smtpd.csr -signkey smtpd.key -out smtpd.crt
openssl rsa -in smtpd.key -out smtpd.key.unencrypted
mv -f smtpd.key.unencrypted smtpd.key
openssl req -new -x509 -extensions v3_ca -keyout cakey.pem -out cacert.pem -days 3650

Next we configure Postfix for TLS:

postconf -e 'smtpd_tls_auth_only = no'
postconf -e 'smtp_use_tls = yes'
postconf -e 'smtpd_use_tls = yes'
postconf -e 'smtp_tls_note_starttls_offer = yes'
postconf -e 'smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key'
postconf -e 'smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt'
postconf -e 'smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem'
postconf -e 'smtpd_tls_loglevel = 1'
postconf -e 'smtpd_tls_received_header = yes'
postconf -e 'smtpd_tls_session_cache_timeout = 3600s'
postconf -e 'tls_random_source = dev:/dev/urandom'
postconf -e 'myhostname = server1.example.com'

The file /etc/postfix/main.cf should now look like this:

# See /usr/share/postfix/main.cf.dist for a commented, more complete version # Debian specific: Specifying a file name will cause the first # line of that file to be used as the name. The Debian default # is /etc/mailname. #myorigin = /etc/mailname smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu) biff = no # appending .domain is the MUA's job. append_dot_mydomain = no # Uncomment the next line to generate "delayed mail" warnings #delay_warning_time = 4h # TLS parameters smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key smtpd_use_tls = yes smtpd_tls_session_cache_database = btree:${queue_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${queue_directory}/smtp_scache # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for # information on enabling SSL in the smtp client. myhostname = server1.example.com alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases myorigin = /etc/mailname mydestination = server1.example.com, localhost.example.com, localhost relayhost = mynetworks = 127.0.0.0/8 mailbox_command = procmail -a "$EXTENSION" mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all inet_protocols = all smtpd_sasl_local_domain = smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous broken_sasl_auth_clients = yes smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination smtpd_tls_auth_only = no smtp_use_tls = yes smtp_tls_note_starttls_offer = yes smtpd_tls_CAfile = /etc/postfix/ssl/cacert.pem smtpd_tls_loglevel = 1 smtpd_tls_received_header = yes smtpd_tls_session_cache_timeout = 3600s tls_random_source = dev:/dev/urandom

Restart Postfix:

/etc/init.d/postfix restart

Authentication will be done by saslauthd. We have to change a few things to make it work properly. Because Postfix runs chrooted in /var/spool/postfix we have to do the following:

mkdir -p /var/spool/postfix/var/run/saslauthd

Now we have to edit /etc/default/saslauthd in order to activate saslauthd. Remove # in front of START=yes and add the line PARAMS="-m /var/spool/postfix/var/run/saslauthd -r":

vi /etc/default/saslauthd

# This needs to be uncommented before saslauthd will be run automatically START=yes PARAMS="-m /var/spool/postfix/var/run/saslauthd -r" # You must specify the authentication mechanisms you wish to use. # This defaults to "pam" for PAM support, but may also include # "shadow" or "sasldb", like this: # MECHANISMS="pam shadow" MECHANISMS="pam"

We must also edit /etc/init.d/saslauthd and change the location of saslauthd's PID file. Change the value of PIDFILE to /var/spool/postfix/var/run/${NAME}/saslauthd.pid:

vi /etc/init.d/saslauthd

[...] PIDFILE="/var/spool/postfix/var/run/${NAME}/saslauthd.pid" [...]

Now start saslauthd:

/etc/init.d/saslauthd start

To see if SMTP-AUTH and TLS work properly now run the following command:

telnet localhost 25

After you have established the connection to your Postfix mail server type

ehlo localhost

If you see the lines

250-STARTTLS

and

250-AUTH

everything is fine.

Type

quit

to return to the system's shell.

12 Courier-IMAP/Courier-POP3

Run this to install Courier-IMAP/Courier-IMAP-SSL (for IMAPs on port 993) and Courier-POP3/Courier-POP3-SSL (for POP3s on port 995):

apt-get install courier-authdaemon courier-base courier-imap courier-imap-ssl courier-pop courier-pop-ssl courier-ssl gamin libgamin0 libglib2.0-0

You will be asked two questions:

Create directories for web-based administration ? <-- No
SSL certificate required <-- Ok

If you do not want to use ISPConfig, configure Postfix to deliver emails to a user's Maildir*:

postconf -e 'home_mailbox = Maildir/'
postconf -e 'mailbox_command ='
/etc/init.d/postfix restart

*Please note: You do not have to do this if you intend to use ISPConfig on your system as ISPConfig does the necessary configuration using procmail recipes. But please go sure to enable Maildir under Management -> Server -> Settings -> EMail in the ISPConfig web interface.