How to comply with Google and Yahoo’s requirements for bulk email senders

An image generated by the Midjourney AI 6.0 alpha model using the prompt: An envelope sealed with a wax seal embossed with the word "DMARC"

To help protect their customers from malicious and junk emails, Google and Yahoo have announced that they will begin to enforce additional requirements for emails from bulk email senders in February 2024. Failure to meet these requirements will result in emails being placed in the spam folder instead of the inbox, or possibly not being delivered at all. This includes both personal and business inboxes. Other email providers are expected to follow suit, so any application that sends email should work towards adhering to these requirements, regardless of recipients or message volume.

Update: Google has begun to reject messages from bulk senders that do not comply with authentication requirements.

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How to create a single-node Graylog instance and analyze FortiGate logs

A screenshot of the Application Control dashboard included in the FortiGate Syslog Content Pack for Graylog

Firewall logs provide a wealth of information about a network. They can be used to identify devices, troubleshoot policies, and even help determine the impact of a cyber attack. Graylog is a powerful open source log collection and analysis platform that is well-suited for managing firewall logs. This guide explains how to create a production-ready single node Graylog instance with bidirectional authentication to the firewalls, and how it can be used to analyze FortiGate firewall logs with premade dashboards.

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How to update the firmware on a Samsung monitor

Image of a Samsung Moniter with a Level Up sign in front.

Almost every device you can buy nowadays has upgradable firmware. New firmware versions can fix bugs, patch security vulnerability, improve features, or add features. As computer monitors get more complex and feature-packed, it becomes more important to use the latest firmware. Samsung doesn’t provide instructions on performing a firmware update in user guides on on download pages. This guide explains the exact steps for updating the firmware on Samsung monitor, and will hopefully save you a lot of searching.

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How to use Farsight Security’s DNSDB to harness the power of passive DNS

The logo of Farsight Security, makers of the DNSDB passive DNS service

DNS describes the structure of resources on the internet. It can provide lots of valuable information about (attacker or target) infrastructure. However, in order to query DNS records, you must already know the exact domains or subdomains to query. When examining unknown infrastructure, this is not practical. On top of that, DNS records can change often, so historical information is lost. Passive DNS databases help solve both of these problems. Farsight Security DNSDB is the largest passive DNS database in the world. With DNSDB, you can answer questions like “How has this network infrastructure changed over time?”, “What other domains and subdomain point (or have pointed to) this IP address?”, “What are the subdomains and resource records for this domain?”

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How to configure a nginx reverse proxy with Let’s Encrypt certificates

The Let's Encrypt logo

The certbot utility by the Electronic Fronter Foundation (EFF) can use DNS authentication to obtain, install, and renew free trusted SSL certificates on a variety of webserver configurations, including a nginx reverse proxy.

This configuration can be used on internal and external websites. It is particularly useful in situations where you want to have a trusted certificate for an internal web application without the time, effort, and risks of creating and maintaining your own internal Certificate Authority (CA).

As an example, this guide will explain how to configure nginx with a trusted certificate to act as a reverse proxy in front of a Unifi Controller.

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How to forward a forensic copy of an email as an attachment

If you receive a fraudulent email, can be very useful to send a full forensic copy to an organization that is being spoofed, industry partners, and law enforcement.

When a user clicks forward in a mail client, the client copies the message’s content and attachments to a new message. The original message headers are not included.

In order to send a full forensic sample that includes the original message headers, the original message must be sent as an attachment in a new message. The process for doing this varies by mail client.

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How to view email headers

A screenshot of email headers

Email headers contain very useful information for tracing a message’s origin and troubleshooting its delivery. Email headers are written with the oldest headers at the bottom, and the newest headers at the top. By reading the headers in the correct order, you can see how the message was passed from one mail server to another, and the actions each mail server took along the way.

Most email clients have a function to display a message’s headers. The exact steps depends on the client.

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Demystifying DMARC: A guide to preventing email spoofing

A screenshot of a premade aggreate/summary DMARC dashboard in ELK using data from pardeemarc

DMARC can stop spoofed spam and phishing from reaching you and your customers, protecting your information security and your brand. However, complexity and misconceptions deter many organizations from ever deploying it. Part mythbusting , part implementation guide, this post explains the shortcomings of SPF and DKIM, what DMARC is, how to deploy DMARC properly, and how to respond to DMARC reports – all without the need for an additional vendor, thanks to open source software!

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