How to configure SMTP verification using LDAP in Kaspersky Secure Mail Gateway


Kaspersky Secure Mail Gateway


How to configure SMTP verification using LDAP in Kaspersky Secure Mail Gateway

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2019 Jan 18 ID: 12300

The guide is applicable for cases when several LDAP servers are used. If the servers have different search_base or accounts, create a configuration file for each server. Add the created files to the relay_recipient_maps options. When integrating with one of the servers through the LDAPS protocol, add version=3 to the configuration file for that server to avoid the warning which postmap generates because of the default protocol value.


To enable SMTP verification using LDAP:

  1. Open the console of the Kaspersky Secure Mail Gateway virtual machine or connect to it via SSH.
  2. Go to Technical Support Mode.
  3. Copy the file /opt/kaspersky/klms-appliance/share/postfix/
  4. In the original file, find  relay_recipient_maps
  5. Delete the following lines:
{% if rejectRecipient == "unlisted" -%}
{%- endif %}
  1. Add the following line below:
relay_recipient_maps = ldap:$config_directory/
  1. Make sure the file includes the following parameters:
smtpd_recipient_restrictions = reject_unlisted_recipient,  reject_non_fqdn_recipient,  reject_unknown_recipient_domain,  permit_mynetworks,  reject_unauth_destination,  reject_unverified_recipient
smtpd_reject_unlisted_recipient = yes
  1. Save the file.
Changing of the settings related to reject_unlisted_recipient will become unavailable after you save the file
  1. Open the file /etc/postfix/
  2. Fill it in according to the example:
SSL is supported. In this case, the link must start with ldaps:// 
server_host = ldap://
server_port = 389
search_base = dc=site
query_filter = mail=%s
result_attribute = mail
bind = yes
bind_dn = cn=admin,dc=site
bind_pw = <your password here>
bind parameters are optional, if anonymous access to LDAP is available. 
For description of all parameters, see the Postfix official website.
  1. Save the file and run the command:
postmap /etc/postfix/
  1. Check if you can find users by their email addresses:
postmap -q ldap:/etc/postfix/  
If the address exists and the search works, the information about the address will appear on the screen.
  1. Update the configuration of postfix:

If the settings are correct, upon attempts to send a message to the user outside LDAP, you will get the error:

Non existing user:
Feb 26 17:53:50 adagsd postfix/smtpd[10029]: NOQUEUE: reject: RCPT from adagsd.test.local[::1]: 550 5.1.1 <>: Recipient address rejected: User unknown in relay recipient table; from=<root@adagsd.test.local> to=<> proto=ESMTP helo=<adagsd.test.local>

The settings will not function if Trusted Networks is used. For details, please see the Postfix website.

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