El Servidor Perfecto - CentOS 5.3 x86_64 [ISPConfig 2] - Página 5

11 Postfix Con SMTP-AUTH Y TLS

Ahora instalamos Postfix y Dovecot (Dovecot será nuestro servidor POP3/IMAP):

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

A continuación configuramos SMTP-AUTH y 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_sasl_authenticated_header = yes'
postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination'
postconf -e 'inet_interfaces = all'
postconf -e 'mynetworks = 127.0.0.0/8'

Debemos editar /usr/lib64/sasl2/smtpd.conf para que Postfix permita inicios de sesión PLAIN y LOGIN. En un Centos 5.3 de 32 bits, debes editar el archivo /usr/lib/sasl2/smtpd.conf en su lugar. Debería verse así:

vi /usr/lib64/sasl2/smtpd.conf

| pwcheck_method: saslauthd mech_list: plain login |

Después creamos los certificados para 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

A continuación configuramos Postfix para 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'

Luego establecemos el nombre del host en nuestra instalación de Postfix (asegúrate de reemplazar server1.example.com con tu propio nombre de host):

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

Después de estos pasos de configuración, ahora deberías tener un /etc/postfix/main.cf que se vea así (he eliminado todos los comentarios de él):

cat /etc/postfix/main.cf

| 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 = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin 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_sasl_authenticated_header = yes smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination mynetworks = 127.0.0.0/8 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 myhostname = server1.example.com |

Por defecto, el demonio Dovecot de CentOS proporciona solo servicios IMAP e IMAPs. Debido a que también queremos POP3 y POP3s, debemos configurar Dovecot para hacerlo. Editamos /etc/dovecot.conf y habilitamos la línea 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. # "[::]" listens in all IPv6 interfaces, but may also listen in all IPv4 # interfaces depending on the operating system. [...] |

Ahora inicia Postfix, saslauthd y 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

Para ver si SMTP-AUTH y TLS funcionan correctamente, ahora ejecuta el siguiente comando:

telnet localhost 25

Después de haber establecido la conexión con tu servidor de correo Postfix, escribe

ehlo localhost

Si ves las líneas

250-STARTTLS

y

250-AUTH PLAIN LOGIN

todo está bien.

[root@server1 ssl]# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
220 server1.example.com ESMTP Postfix
ehlo localhost
250-server1.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
quit
221 2.0.0 Bye
Connection closed by foreign host.
[root@server1 ssl]#

Escribe

quit

para volver a la shell del sistema.

11.1 Maildir

Dovecot utiliza el formato Maildir (no mbox), así que si instalas ISPConfig en el servidor, asegúrate de habilitar Maildir en Management -> Server -> Settings -> Email. ISPConfig hará la configuración necesaria.

Si no deseas instalar ISPConfig, entonces debes configurar Postfix para entregar correos electrónicos al Maildir de un usuario (también puedes hacer esto si usas ISPConfig - no hace daño ;-)):

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