Difference between revisions of "Email relay"
 
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=Installation=
 
=Installation=
  
 +
<syntaxhighlight lang="bash">
 
apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
 
apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
 +
</syntaxhighlight>
  
 +
Choose:
 +
* Internet Site
 +
* Type your FQDN like: dev.daxiongmao.eu  ||  smartcard-gw.smartcards.vehco.com
 +
 +
 +
 +
 +
=Configuration=
 +
 +
 +
==POSTFIX global conf==
  
 
Edit Postfix configuration
 
Edit Postfix configuration
  
 +
<syntaxhighlight lang="bash">
 +
vim /etc/postfix/main.cf
 +
</syntaxhighlight>
  
  
 +
Add / adjust the SMTP relay and SASL settings (~ line 37)
  
−
Set SMTP relay and SASL settings
+
<syntaxhighlight lang="bash">
 +
## SMTP relay  
 +
relayhost = [smtp.gmail.com]:587
 +
smtp_sasl_auth_enable = yes
 +
smtp_sasl_password_maps = hash:/etc/postfix/sasl_password
 +
smtp_sasl_security_options = noanonymous
 +
smtp_sasl_tls_security_options = noanonymous
 +
smtp_tls_policy_maps = hash:/etc/postfix/tls_policy
 +
</syntaxhighlight>
  
  
 +
Do not change the default TLS settings !!
  
  
 +
==Credentials file==
  
 
Create login / password file
 
Create login / password file
 +
 +
<syntaxhighlight lang="bash">
 
vim /etc/postfix/sasl_password
 
vim /etc/postfix/sasl_password
 +
</syntaxhighlight>
  
  
 
Put the following content
 
Put the following content
 +
 +
<syntaxhighlight lang="bash">
 
[smtp.gmail.com]:587    USERNAME@gmail.com:PASSWORD
 
[smtp.gmail.com]:587    USERNAME@gmail.com:PASSWORD
 +
</syntaxhighlight>
  
  
−
Set rights
+
Compute new hash for postfix
−
chmod 640 /etc/postfix/sasl_password
 
−
chown postfix:postfix /etc/postfix/sasl_password
 
  
 +
<syntaxhighlight lang="bash">
 +
postmap /etc/postfix/sasl_password
 +
</syntaxhighlight>
  
−
Compute new hash for postfix
 
−
chown -R postfix /etc/postfix
 
−
postmap /etc/postfix/sasl_password
 
  
 +
==TLS policy==
  
 
Create TLS policy file
 
Create TLS policy file
 +
 +
<syntaxhighlight lang="bash">
 
vim /etc/postfix/tls_policy
 
vim /etc/postfix/tls_policy
 +
</syntaxhighlight>
  
  
 
Put the following content
 
Put the following content
 +
 +
<syntaxhighlight lang="bash">
 
[smtp.gmail.com]:587 encrypt
 
[smtp.gmail.com]:587 encrypt
 +
</syntaxhighlight>
  
  
 
Compute new hash for postfix
 
Compute new hash for postfix
 +
 +
<syntaxhighlight lang="bash">
 
postmap /etc/postfix/tls_policy
 
postmap /etc/postfix/tls_policy
 +
</syntaxhighlight>
 +
 +
 +
==Apply changes==
 +
 +
You must restart POSTFIX to apply changes
 +
 +
<syntaxhighlight lang="bash">
 +
service postfix restart
 +
/etc/init.d/postfix/reload
 +
</syntaxhighlight>
 +
 +
 +
 +
 +
 +
=Test your configuration=
 +
 +
<syntaxhighlight lang="bash">
 +
echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" target@domain.com
  
 +
## Multi-users
 +
echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" target@domain.com,target2@domain.com
 +
</syntaxhighlight>
  
−
Test you configuration
 
  
 +
Check your logs!! <code>cat /var/log/syslog</code>
  
  
−
Check your logs!
 
  
−
cat /var/log/mail.log
 
  
 +
=Configure aliases=
  
−
You should see something like:
+
To send all email address to "root" to your particular address you must create some aliases.
  
−
''Aug 13 10:15:46 smartcard-gw postfix/pickup[11711]: 558D442DDF: uid=0 from=<root@dev>
+
<syntaxhighlight lang="bash">
 +
vim /etc/aliases
 +
</syntaxhighlight>
  
−
Aug 13 10:15:46 smartcard-gw postfix/cleanup[11836]: 558D442DDF: message-id=<20140813081546.558D442DDF@dev>
+
Put something like:  
 +
<syntaxhighlight lang="bash">
 +
# See man 5 aliases for format
 +
postmaster:   root
 +
root:         me@mydomain.lu, you@mydomain.lu
 +
</syntaxhighlight>
  
−
Aug 13 10:15:46 smartcard-gw postfix/qmgr[11712]: 558D442DDF: '''''from=<root@dev.daxiongmao.eu>''''', size=361, nrcpt=1 (queue active)
+
Apply changes:
 +
<syntaxhighlight lang="bash">
 +
# Apply aliases to all the system
 +
newaliases
  
−
Aug 13 10:15:48 smartcard-gw postfix/smtp[11838]: 558D442DDF: '''''to=<target@domain.com>''', '''relay=smtp.gmail.com'''''[173.194.71.108]:587, delay=2.4, delays=0.02/0.04/0.89/1.5, dsn=2.0.0, '''''status=sent''' (250 2.0.0 OK 1407917748 n2sm761208lag.18 - gsmtp)''
+
# Restart postfix
 +
service postfix restart
 +
/etc/init.d/postfix/reload
 +
</syntaxhighlight>
  
−
Aug 13 10:15:48 smartcard-gw postfix/qmgr[11712]: 558D442DDF: removed''
 
  
  
  
−
cat /var/log/mail.err
+
=Test your aliases=
  
 +
<syntaxhighlight lang="bash">
 +
echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" root
 +
</syntaxhighlight>
  
  
  
  
 +
=Usage=
  
 +
The usage is transparent.
  
−
=Sources=
+
A lot of services like Zabbix, Nagios, Webmin... are already using the "mail" application. So you don't need to do anything on your side! :-)

Latest revision as of 11:52, 21 January 2017


Principle

Our server will forward all emails to another SMTP server. The SMTP server we're gonna install is stupid: only local domain, no account checking, no anti-virus or spam protection.

  1. From a local point of view, all emails are send using Linux default configuration and system users
  2. From the other hand - the big SMTP server ("Gmail", "Outlook", ...) - all emails come from the same account


Principle:

SMTP server relay


As you can see, POSTFIX SMTP server will just act as a proxy between local services and Gmail.



When to use it ?

If you only have a single server and want to monitor it, then use a relay! That's much easier than setup a complete email server. It's also easier to maintain!



Installation

apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules

Choose:

  • Internet Site
  • Type your FQDN like: dev.daxiongmao.eu || smartcard-gw.smartcards.vehco.com



Configuration

POSTFIX global conf

Edit Postfix configuration 

vim /etc/postfix/main.cf


Add / adjust the SMTP relay and SASL settings (~ line 37) 

## SMTP relay 
relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_password
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_policy_maps = hash:/etc/postfix/tls_policy


Do not change the default TLS settings !!


Credentials file

Create login / password file 

vim /etc/postfix/sasl_password


Put the following content 

[smtp.gmail.com]:587    USERNAME@gmail.com:PASSWORD


Compute new hash for postfix 

postmap /etc/postfix/sasl_password


TLS policy

Create TLS policy file 

vim /etc/postfix/tls_policy


Put the following content 

[smtp.gmail.com]:587 encrypt


Compute new hash for postfix 

postmap /etc/postfix/tls_policy


Apply changes

You must restart POSTFIX to apply changes 

service postfix restart
/etc/init.d/postfix/reload



Test your configuration

echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" target@domain.com

## Multi-users
echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" target@domain.com,target2@domain.com


Check your logs!! cat /var/log/syslog



Configure aliases

To send all email address to "root" to your particular address you must create some aliases. 

vim /etc/aliases

Put something like: 

# See man 5 aliases for format
postmaster:    root
root:          me@mydomain.lu, you@mydomain.lu

Apply changes: 

# Apply aliases to all the system
newaliases

# Restart postfix
service postfix restart
/etc/init.d/postfix/reload



Test your aliases

echo "Test from my new SMTP relay" | mail -s "Test Postfix SMTP relay" root



Usage

The usage is transparent.

A lot of services like Zabbix, Nagios, Webmin... are already using the "mail" application. So you don't need to do anything on your side! :-)

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