Secure Outgoing SMTP via Postfix, Courier, TLS and SASL

From Wiki

Jump to: navigation, search
  • OK. First off: apt-get
apt-get install postfix-tls libsasl2-2 sasl2-bin libsasl2-modules

Main Website used for Config: http://www.falkotimme.com/howtos/perfect_setup_debian_sarge/index.php

Secondard Website - however uses a different Auth file: http://www.tribulaciones.org/docs/postfix-sasl-tls-howto.html

More Good Info & a SIMPLE WAY TO OVERCOME CHROOT -> http://wiki.ev-15.com/debian:mail_system


A lot of the following is old and not required in debian squeeze:

  • Configing:

/etc/postfix/main.cf
/etc/postfix/sasl/smtpd.conf
/etc/postfix/ssl/* - tls certs

1. 
# SASL Support
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
2.
# SASL Auth
vi /etc/postfix/sasl/smtpd.conf
pwcheck_method: saslauthd
mech_list: plain login
3.
# TLS Certs
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

# TLS Config in /etc/postfix/main.cf # Moving onto TLS on its own. smtpd_tls_auth_only = yes 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

vi /etc/postfix/main.cf
//add in
smtpd_sasl_auth_enable = yes
//Then try and send emails via smtpd
  • Restart Postfix

Now continuing onto Auth
Because postfix runs chrooted - need to move the /var/run dir

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

Edit /etc/default/saslauthd

Remove # in front of START=yes
Add the line PARAMSOPTIONS="-m /var/spool/postfix/var/run/saslauthd"

Edit /etc/init.d/saslauthd

Add a # to dir=`dpkg-statoverride --list $PWDIR`
Add in dir=".... below the PIDFILE entry
#dir=`dpkg-statoverride --list $PWDIR`
Change PWDIR and PIDFILE to the following:
PWDIR="/var/spool/postfix/var/run/${NAME}"
PIDFILE="${PWDIR}/saslauthd.pid"
dir="root sasl 755 ${PWDIR}"
//change to:
createdir root sasl 755 $RUN_DIR
  • Save & Close
  • restart saslauthd
  • /etc/init.d/saslauthd start
  • MAKE SURE TO ADJUST FIREWALL - OPEN UP PORT 111 Locally

Debugging and testing

user@otherserver:~$ telnet mail.burkesys.com 25
Trying 78.47.9.122...
Connected to mail.burkesys.com.
Escape character is '^]'.
220 mail.burkesys.com ESMTP Postfix (Debian/GNU)
ehlo localhost
250-mail.burkesys.com
250-PIPELINING
250-SIZE 20000000
250-ETRN
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

After connecting via telnet, type "ehlo localhost" and watch for the "STARTTLS" line. This *should* show up.

Of course o2 have started filtering external traffic over port 25, and filterting out the starttls which makes life difficult for thunderbird. See: http://markmail.org/message/v5uofqpx5l5pu4rm Just as well I have port 587 open for use with a nice iptable rule:

iptables -t nat -A PREROUTING -p tcp --dport 587 -j DNAT --to ip.address:25
iptables -t nat -L
iptables -t nat -D PREROUTING 1
Personal tools