Postfix With SMTP-AUTH And TLS Debian

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

apt-get install postfix libsasl2-2 sasl2-bin libsasl2-modules libdb3-util procmail

You will be asked two questions. Answer as follows:

General type of mail configuration: <-- Internet Site
System mail name: <-- server1.example.com

Then run

dpkg-reconfigure postfix

Again, you'll be asked some questions:

General type of mail configuration: <-- Internet Site
System mail name: <-- server1.example.com
Root and postmaster mail recipient: <-- [blank]
Other destinations to accept mail for (blank for none): <-- server1.example.com, localhost.example.com, localhost.localdomain, 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 (make sure that you use the correct hostname for myhostname):

postconf -e 'myhostname = server1.example.com'
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'

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

cat /etc/postfix/main.cf

# 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:${queue_directory}/smtp_scache # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for # information on enabling SSL in the smtp client. myhostname = server1.example.com alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases myorigin = /etc/mailname mydestination = server1.example.com, localhost.example.com, localhost.localdomain, localhost relayhost = mynetworks = 127.0.0.0/8 mailbox_command = procmail -a "$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. Set START to yes and change the line OPTIONS="-c" to OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd -r":

vi /etc/default/saslauthd

# # Settings for saslauthd daemon # # Should saslauthd run automatically on startup? (default: no) START=yes # Which authentication mechanisms should saslauthd use? (default: pam) # # Available options in this Debian package: # getpwent -- use the getpwent() library function # kerberos5 -- use Kerberos 5 # pam -- use PAM # rimap -- use a remote IMAP server # shadow -- use the local shadow password file # sasldb -- use the local sasldb database file # ldap -- use LDAP (configuration is in /etc/saslauthd.conf) # # Only one option may be used at a time. See the saslauthd man page # for more information. # # Example: MECHANISMS="pam" MECHANISMS="pam" # Additional options for this mechanism. (default: none) # See the saslauthd man page for information about mech-specific options. MECH_OPTIONS="" # How many saslauthd processes should we run? (default: 5) # A value of 0 will fork a new process for each connection. THREADS=5 # Other options (default: -c) # See the saslauthd man page for information about these options. # # Example for postfix users: "-c -m /var/spool/postfix/var/run/saslauthd" # Note: See /usr/share/doc/sasl2-bin/README.Debian OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd -r"

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