Postfix com SMTP-AUTH e TLS

Para instalar o Postfix com SMTP-AUTH e TLS , realize os seguintes passos:

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

Serão perguntadas duas questões. Responda como a seguir:

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

Então, execute

dpkg-reconfigure postfix

Novamente, serão perguntadas algumas questões:


General type of mail configuration: <– Internet Site
System mail name: <– server1.example.com
Root and postmaster mail recipient: <– [branco]
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

A seguir, faça isto:

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

Depois, criaremos os certificados para o 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 seguir, configuramos o Postfix para o TLS (assegure-se de que você utilliza o hostname correto para 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’

O arquivo /etc/postfix/main.cf deve se parecer agora com isto:

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

Reinicialize o Postfix:

/etc/init.d/postfix restart

A Authenticação será realizada pelo saslauthd. Temos que modificar algumas poucas coisas para fazê-lo funcionar coretamente. Porque o Postfix roda “chrooted” em /var/spool/postfix , temos que fazer o seguinte:

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

Agora, temos que editar o arquivo /etc/default/saslauthd para ativar o saslauthd. Modifique START para yes e modifique a linha OPTIONS=”-c” para 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”

Agora, inicialize o saslauthd:

/etc/init.d/saslauthd start

Para verificar se o SMTP-AUTH e o TLS estão funcionando perfeitamente, agora, execute o seguinte comando:

telnet localhost 25

Depois que já estiver estabelecido a conexão com o seu servidor de e-mail Postfix, digite

ehlo localhost

Se você visualizar as linhas

250-STARTTLS

e

250-AUTH PLAIN LOGIN

tudo correu bem.

A saída, no meu sistema, se parece com esta:

root@server1:/etc/postfix/ssl# telnet localhost 25
Trying 127.0.0.1…
Connected to localhost.localdomain.
Escape character is ‘^]’.
220 server1.example.com ESMTP Postfix (Ubuntu)
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:/etc/postfix/ssl#

Digite

quit

para retornar ao shell do sistema..