CNM Mail Server

CNM Mail Server (hereinafter, the Soft) is the server that makes sure that all CNM apps can send and, when applicable, receive emails through it.

Development of the Soft occurs under the Mail for CNM Cloud project.

Architecture

Postfix + Dovecot

It deploys the most popular combination of Postfix and Dovecot for mail setup.

Postfix is the Mail Transfer Agent. Postfix is free software, featuring a clever modular architecture that allows you to create a reliable and fast mail system.

Dovecot is a free IMAP and POP3 server that offers security, configuration flexibility, and performance. Dovecot features are:

1. High-performance
2. A large number of supported mechanisms for storing authentication information (including LDAP) and authentication itself (SSL is supported).
3. Extensibility via plugins.
4. Strict adherence to standards. Dovecot is one of the few servers to pass all IMAP standards tests.

We use the combination because Postfix just concerns itself with sending off client emails and temporarily storing incoming emails without sorting them according to recipient email address. And Dovecote's principal task is sorting the emails received by the mail transfer agent (MTA), e.g. Postfix, and delivering them on demand by each recipient. It separates the mass of emails arriving at Postfix's single mailbox into individual mailboxes for each recipient address and simultaneously listens for requests for a new email from recipients' email client packages.

The architecture of the mail server looks like this:

The input is the MTA mail server which works on the SMTP protocol. The MTA is on the Internet and it gets and sends the mail. We have some sort of mail base and we also have a mail delivery agent called MDA which delivers mail to the user. This is a POP3 or IMAP protocol. The MDA takes from the email base and gives it to the client. In between is the LDA, which takes mail from the MDA via LMTP (Local Mail Transfer Protocol) and puts it in the database.

Usually, you don't put extra software as an LDA. Today, both Postfix and Dovecot can act as an LDA. But Postfix does it in a very primitive way. If you use Dovecot, however, it is possible to connect Sieve (a scripting language for mail filtering) and much more.

Software instances

Software instances that power (1) core, (2) hands-on training, and (3) experiential systems and applications.

1. mail.opplet.net (core) opplet-test
2. mail.cnmcyber.com (experiential systems and applications) employ

Security

For security, we use Fail2ban because it operates by monitoring log files (e.g. /var/log/auth.log, /var/log/apache/access.log, etc.) for selected entries and running scripts based on them. Most commonly this is used to block selected IP addresses that may belong to hosts that are trying to breach the system's security. It can ban any host IP address that makes too many login attempts or performs any other unwanted action within a time frame defined by the administrator. Includes support for both IPv4 and IPv6.

Malware protection

Previously, Opplet developers struggled with the viruses, so an effective anti-virus strategy must be found -- what was the solution?

Standing operating procedures

Standing operating procedure

• Нow to install Postfix and Dovecot:
• How to install Spam Assassin:
• How to configure DNS:
• How to set up Email message management in Dovecot:
• How to encrypt traffic in Postfix:

Hands-on assignments

Hands-on assignments that CNM learners can use to get accustomed to the software while using its hands-on training systems and applications.

Presentations

Presentations that present the software to its new users in multimedia, video, just audio, and/or just graphic formats.

User group

CNM Social user group has not yet been created; the group may organize software-related events and produce newsletters.

Related lectios

Lectios that provide CNM learners with knowledge about the deployed software.