The Perfect Setup - CentOS 5.0 (32-bit) - Page 5

11 Postfix With SMTP-AUTH And TLS

Now we install Postfix and Dovecot (Dovecot will be our POP3/IMAP server):

yum install cyrus-sasl cyrus-sasl-devel cyrus-sasl-gssapi cyrus-sasl-md5 cyrus-sasl-plain postfix dovecot

Next we configure SMTP-AUTH and TLS:

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'
postconf -e 'mynetworks ='

We must edit /usr/lib/sasl2/smtpd.conf so that Postfix allows PLAIN and LOGIN logins. On a 64Bit Centos 5.0 you must edit the file /usr/lib64/sasl2/smtpd.conf instead. It should look like this:

vi /usr/lib/sasl2/smtpd.conf

pwcheck_method: saslauthd
mech_list: plain login

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'

After these configuration steps you should now have a /etc/postfix/ that looks like this (I have removed all comments from it):

cat /etc/postfix/

queue_directory = /var/spool/postfix
command_directory = /usr/sbin
daemon_directory = /usr/libexec/postfix
mail_owner = postfix
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost
unknown_local_recipient_reject_code = 550
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
debug_peer_level = 2
debugger_command =
         xxgdb $daemon_directory/$process_name $process_id & sleep 5

sendmail_path = /usr/sbin/sendmail.postfix
newaliases_path = /usr/bin/newaliases.postfix
mailq_path = /usr/bin/mailq.postfix
setgid_group = postdrop
html_directory = no
manpage_directory = /usr/share/man
sample_directory = /usr/share/doc/postfix-2.3.3/samples
readme_directory = /usr/share/doc/postfix-2.3.3/README_FILES
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
mynetworks =
smtpd_tls_auth_only = no
smtp_use_tls = yes
smtpd_use_tls = yes
smtp_tls_note_starttls_offer = yes
smtpd_tls_key_file = /etc/postfix/ssl/smtpd.key
smtpd_tls_cert_file = /etc/postfix/ssl/smtpd.crt
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

By default, CentOS' Dovecot daemon provides only IMAP and IMAPs services. Because we also want POP3 and POP3s we must configure Dovecot to do so. We edit /etc/dovecot.conf and enable the line protocols = imap imaps pop3 pop3s:

vi /etc/dovecot.conf

# Base directory where to store runtime data.
#base_dir = /var/run/dovecot/

# Protocols we want to be serving: imap imaps pop3 pop3s
# If you only want to use dovecot-auth, you can set this to "none".
protocols = imap imaps pop3 pop3s

# IP or host address where to listen in for connections. It's not currently
# possible to specify multiple addresses. "*" listens in all IPv4 interfaces.

Now start Postfix, saslauthd, and Dovecot:

chkconfig --levels 235 sendmail off
chkconfig --levels 235 postfix on
chkconfig --levels 235 saslauthd on
chkconfig --levels 235 dovecot on
/etc/init.d/sendmail stop
/etc/init.d/postfix start
/etc/init.d/saslauthd start
/etc/init.d/dovecot 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




everything is fine.

[root@server1 ssl]# telnet localhost 25
Connected to localhost.localdomain (
Escape character is '^]'.
220 ESMTP Postfix
ehlo localhost
250-SIZE 10240000
250 DSN
221 2.0.0 Bye
Connection closed by foreign host.



to return to the system's shell.


11.1 Maildir

Dovecot uses Maildir format (not mbox), so if you install ISPConfig on the server, please make sure you enable Maildir under Management -> Server -> Settings -> Email. ISPConfig will then do the necessary configuration.

If you do not want to install ISPConfig, then you must configure Postfix to deliver emails to a user's Maildir (you can also do this if you use ISPConfig - it doesn't hurt ;-)):

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

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8 Comment(s)

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From: TechSpotting at: 2011-08-02 16:29:36

I have written a guide here on how to install CentOS 6 for server or desktops.

 It's for x86_64 some users might find it useful!

From: Mickey Knox at: 2011-12-20 03:25:14

for those who speak spanish (the translation to english is pending), I developed my own bash script to configure CentOS (or Redhat). is my version of the perfect server (post installation).

You can test it here:

From: Jason Barnett at: 2009-02-08 10:14:43


In order to install ncftp I had to add the using the following commands:

cd /etc/yum.repos.d/


vi kbsingh-CentOS-Extras.repo

change enabled=0 to enabled=1 as follows:

name=CentOS.Karan.Org-EL$releasever - Testing

rpm --import

and finally yum install ncftp

From: at: 2007-06-22 16:03:47

If you want to use the chmod in ISPConfig you have to change the lines in "/etc/proftpd.conf":




Yours sincerely mawi 

From: Anonymous at: 2010-10-28 01:14:36

First of all NEVER DO ANYTHING TO THE /TMP DIRECTORY!!!!! I cannot stress this enough. Doing so could damage your install. The OS uses this directory as its workspace.

Second, CentOS now has proftpd on yum, I believe it is on the RPMForge repo.
View how to add this repo HERE.

For those who are security minded and do no click links here you go:

Or just Google for centos RPMForge.

From: koka at: 2009-02-10 21:14:21

thanks :)

it really helpes me configure server



From: Anonymous at: 2011-10-05 11:26:34

Thank you

From: John at: 2009-02-23 11:00:08

thanks for the tutorial i have isconfig running now on vmware server - centos 5.0 with webmin to easy manage server.

if you have problem installing message flex run this:

yum install flex

transferring ISPConfig*.tar.gz tru proftpd follow this steps: