Webinar topic: Trusted Email Server DKIM, SPF, DMARC, RDNS Presenter: Achmad Mardiansyah In this webinar series, We are discussing Trusted Email Server DKIM, SPF, DMARC, RDNS Please share your feedback or webinar ideas here: http://bit.ly/glcfeedback Check our schedule for future events: https://www.glcnetworks.com/en/schedule/ Follow our social media for updates: Facebook, Instagram, YouTube Channel, and telegram also discord Recording available on Youtube https://youtu.be/Mkmbj6RSm98

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Trusted Email
Server with
DKIM, SPF,
DMARC, RDNS
GLC Webinar,
30 Sep 2021
Achmad Mardiansyah
achmad@glcnetworks.com
GLC Networks, Indonesia
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TRUSTED SERVER

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Agenda
● Introduction
● Review prerequisite knowledge
● How email system works
● Email server with Linux
● Live practice
● Q & A
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introduction
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What is GLC?
● Garda Lintas Cakrawala (www.glcnetworks.com)
● Based in Bandung, Indonesia
● Areas: Training, IT Consulting
● Certified partner for: Mikrotik, Ubiquity, Linux foundation
● Product: GLC radius manager
● Regular event
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Trainer Introduction
● Name: Achmad Mardiansyah
● Base: bandung, Indonesia
● Linux user since 1999, mikrotik user since 2007, UBNT
2011
● Mikrotik Certified Trainer
(MTCNA/RE/WE/UME/INE/TCE/IPv6)
● Mikrotik/Linux Certified Consultant
● Website contributor: achmadjournal.com, mikrotik.tips,
asysadmin.tips
● More info:
http://au.linkedin.com/in/achmadmardiansyah
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Past experience
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● 2021 (Congo DRC, Malaysia): network support,
radius/billing integration
● 2020 (Congo DRC, Malaysia): IOT integration,
network automation
● 2019, Congo (DRC): build a wireless ISP from
ground-up
● 2018, Malaysia: network revamp, develop billing
solution and integration, setup dynamic routing
● 2017, Libya (north africa): remote wireless migration
for a new Wireless ISP
● 2016, United Kingdom: workshop for wireless ISP,
migrating a bridged to routed network

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About GLC webinar?
● First webinar: january 1, 2010 (title:
tahun baru bersama solaris - new year
with solaris OS)
● As a sharing event with various topics:
linux, networking, wireless, database,
programming, etc
● Regular schedule
● Irregular schedule: as needed
● Checking schedule:
http://www.glcnetworks.com/schedule
● You are invited to be a presenter
○ No need to be an expert
○ This is a forum for sharing: knowledge,
experiences, information
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Please introduce yourself
● Your name
● Your company/university?
● Your networking experience?
● Your mikrotik experience?
● Your expectation from this course?
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Prerequisite
● This presentation some prerequisite knowledge
● We assume you already understand:
○ How computer network works
○ How DNS works
○ Able to administer linux system
○
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Review prerequisite knowledge
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7 OSI layer & protocol
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● OSI layer Is a conceptual model from ISO
(International Standard Organization) for project
OSI (Open System Interconnection)
● When you send a message with a courier, you
need to add more info to get your message arrived
at the destination (This process is called
encapsulation)
● What is protocol
○ Is a set of rules for communication
○ Available on each layer
● Communication consist of series encapsulation
○ SDU: service data unit (before PDU)
○ PDU: protocol data unit (after header is added)

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Layered model (TCP/IP vs ISO) and encapsulation
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/ datagram

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Email System
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How email works
Email components
● MTA: Mail Transfer Agent
(aka. Email server)
● MDA: Mail Delivery
Agent
● MUA: Mail User Agent
○ Local access
○ Remote access
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Source: www.oasis-open.org

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DNS support
To define an MTA, these records must
exist:
● Record A
● Record MX
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Source: amar-linux.blogspot.com

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Email system protocols
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● L7: DNS
○ SMTP: between MTA
○ POP3: MTA - MUA
○ IMAP
● L6: SSL (if used)
● L4: TCP
● L3: IPv4 / IPv6

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Simple mail transport protocol (SMTP)
● Define how SMTP works
● RFC821 → RFC2821 → keep
improving
● Define core components: MTA,
MDA, MUA
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Email system
additional nodes
Email system with a frontend to
user
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Source: amar-linux.blogspot.com

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Trusted email
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Sender Policy Framework (SPF)
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DomainKeys Identified Mail (DKIM)
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Domain-based Message Authentication, Reporting & Conformance
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Tips and trick
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Tips and trick
● Do not make your email server open relay
● Use strong password for user account
● Using email gateway can be useful
● Check email server performance (mxtool)
● Reverse DNS is important
● Use features like SPF, DKIM, DMARC to improve email-server reputation
● Do not send too many email at once
● Always keep the email server reputation up
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Troubleshooting tips
● Start with DNS query
● Log is your friend
○ Ability to use text processing tools (grep, regex, head, tail, etc.) is very helpful
● Use external tools to query
● Check firewall settings
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LIVE practice
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preparation
● SSH client
● SSH parameters
○ SSH address
○ SSH port
○ SSH username
○ SSH password
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Q & A
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Interested? Just come to our training...
● Topics are arranged in systematic and logical way
● You will learn from experienced teacher
● Not only learn the materials, but also sharing experiences, best-practices, and
networking
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End of slides
● Thank you for your attention
● Please submit your feedback: http://bit.ly/glcfeedback
● Find our further event on our website : https://www.glcnetworks.com/en/
● Like our facebook page: https://www.facebook.com/glcnetworks
● Slide: https://www.slideshare.net/glcnetworks/
● Discord (bahasa indonesia): (https://discord.gg/6MZ3KUHHBX)
● Recording (youtube): https://www.youtube.com/c/GLCNetworks
● Stay tune with our schedule
● Any questions?
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