Giovanni F. Mazzeo De Santolo

I ran into an interesting (and frustrating) networking quirk recently that I thought was worth sharing.
If you’re running Split DNS at home—where a subdomain resolves to your WAN IP externally but your router maps it to a different internal LAN IP when you’re inside the network—you might expect things to “just work.” And usually, they do.

But on macOS, if you have iCloud’s “Private Relay” feature enabled, all of your web browsers may fail to resolve that subdomain to the local LAN address. Instead, they try to go out to the WAN IP, breaking your internal routing.

What makes this tricky is that the behavior doesn’t show up in basic tests. Using tools like nslookup or ping in Terminal still returns the correct local IP. Yet in Safari, Chrome, and Brave, the same domain wouldn’t connect to my internal server. The culprit? iCloud Private Relay.

I had assumed that Private Relay would only affect Safari traffic, but it actually interfered with DNS resolution across the system for all browsers. Once I disabled it, everything immediately started working the way it was supposed to.

So, if you’re running Split DNS at home and notice that your browsers refuse to resolve local resources—even though command‑line tools work fine—check whether iCloud Private Relay is enabled. Turning it off solved the problem for me.

Hopefully this tip saves someone else a few hours of head‑scratching.

Last month I passed the CISSP exam, the journey didn’t stop there. Before you can officially call yourself CISSP certified, there’s one last thing to take care of—the endorsement process.

What’s the Endorsement Process About?

Basically, ISC2 checks that:

• You actually have at least five years of cybersecurity work experience.
• You played fair on the exam and didn’t cheat.

You’ll need to complete this step, and pay the ISC2 membership fees, before you can really say you’re CISSP certified.

Here’s some personal news—I’m officially CISSP certified as of today, valid for the next three years! To keep it going, you need to earn Continuing Professional Education (CPE) credits. I’ve put together a list of places where you can get free CPE credits to help with that.

Where to Find Free CPE Credits

Here are some solid options to earn free CPE credits:

• ThreatLocker Webinars
• Hack The Box CPE Guide
• ISC2 Official CPE Partners
• SANS Webcasts
• (Might not be free) Antisyphon Training

Bonus tip: Taking other ISC2 certifications can often count toward your CISSP renewal credits too.

A Few Tips for Renewing Your CISSP

• Keep an eye on your CPE credits so you don’t have to scramble last minute.
• Mix it up with webinars, labs, courses, and events to keep learning interesting.
• Check ISC2’s website every now and then to stay on top of any changes.

Good luck if you’re on this journey—and congrats to anyone who’s passed the exam and completed the endorsement! You’ve earned it.

I’m always curious about how much electricity my homelab devices are consuming, I have implemented a power consumption monitoring and reporting system at home without the use of any cloud services. Everything is self-hosted locally. Sharing some insights on how you too could do this at home.

Hardware & software requirements

• TP-Link or Tapo smart plugs.
  • I am using specifically P115 and EP25 models which are working out of the box with the software stack I chose to use.
• Tapo P316M smart power strip is not working out of the box.
  • Although I am not a coder, I am working to figure it out and have a pull request on github where I try to add support for it.
    • https://github.com/python-kasa/python-kasa/pull/1561
    • https://github.com/python-kasa/python-kasa/issues/1558

The software stack is

• InfluxDB v2 for time series database storage.
• Grafana for visualization and charts of the data.
• https://github.com/lux4rd0/kasa-collector for self-hosted local fetching of power usage metrics from the local network devices, then storing the data in influxdb.

So, is it working?… kinda

I won’t go over setup and complexity but will share some insights and lessons learned. This setup is working as expected for the individual smart plugs with energy monitoring, the smart power strip metrics are not working.

There are some caveats and issues that I think everyone trying to replicate this setup should know about TP-Link and Tapo devices. Unplug any existing TP-link/Tapo devices from your network before onboarding a new device.

• The TP-Link Simple Setup (TSS) protocol, which shares credentials from existing devices, can break authentication with the python-kasa library which is a dependency in this stack.

How do you know TSS broke it?

Check it with the kasa discover command and look for “tss”

root@kasapi:~/python-kasa# uv run kasa --debug --username xx --password "xx" --host 192.168.66.240 discover
DEBUG:kasa.transports.klaptransport:Handshake1 posted at 2025-07-23 14:37:43.119547. Host is 192.168.66.240, Response status is 200, Request was 20708b23c4238cf0ce6da978d69f6e6e
DEBUG:kasa.transports.klaptransport:Handshake1 success at 2025-07-23 14:37:43.119597. Host is 192.168.66.240, Server remote_seed is: fff7df5db632df5ff316dd5f5734dd5e, server hash is: 06a480a245ab224d4875bc8fdcd75a68dc0ebf1a61818f5e194bcb5adc5eb3b0
DEBUG:kasa.transports.klaptransport:Device response did not match our challenge on ip 192.168.66.240, check that your e-mail and password (both case-sensitive) are correct. 
DEBUG:kasa.protocols.smartprotocol:Unable to authenticate with 192.168.66.240, not retrying: Device response did not match our challenge on ip 192.168.66.240, check that your e-mail and password (both case-sensitive) are correct. 
== Authentication failed for device ==
	== Discovery Result ==
	Device Type:        SMART.TAPOPLUG
	Device Model:       P316M(US)
	IP:                 192.168.66.240
	MAC:                REDACTED
	Device Id (hash):   REDACTED
	Owner (hash):       xx
	Supports IOT Cloud: True
	OBD Src:            tss
	Encrypt Type:       KLAP
	HTTP Port:          80
	Login version:      2

What it should look like in order for authentication to not be broken you ask?

root@kasapi:~/python-kasa/python-kasa# uv run kasa discover
== Authentication failed for device ==
        == Discovery Result ==
        Device Type:        SMART.TAPOPLUG
        Device Model:       P115(US)
        IP:                 192.168.66.179
        MAC:                REDACTED
        Device Id (hash):   REDACTED
        Owner (hash):       REDACTED
        Supports IOT Cloud: True
        OBD Src:            tplink
        Encrypt Type:       KLAP
        HTTP Port:          80
        Login version:      2


== Authentication failed for device ==
        == Discovery Result ==
        Device Type:        SMART.TAPOPLUG
        Device Model:       P316M(US)
        IP:                 192.168.66.240
        MAC:                REDACTED
        Device Id (hash):   REDACTED
        Owner (hash):       REDACTED
        Supports IOT Cloud: True
        OBD Src:            tplink
        Encrypt Type:       KLAP
        HTTP Port:          80
        Login version:      2

P316M device information when fully authenticated with proper credentials and no ‘tss’

The below is what you should expect to see:

root@kasapi:~/python-kasa/python-kasa# uv run kasa --username xyz --password xyz --host 192.168.66.240 discover
Discovering device 192.168.66.240 for 10 seconds
== None - P316M ==
Host: 192.168.66.240
Port: 80
Device state: False
Time:         2025-07-24 12:45:51-04:00 (tz: America/New_York)
Hardware:     1.6 (US)
Firmware:     1.0.5 Build 250306 Rel.151943
MAC (rssi):   REDACTED (-46)

== Primary features ==

== Information ==
Signal Level (signal_level): 3
Cloud connection (cloud_connection): True
Update available (update_available): None
Check latest firmware (check_latest_firmware): <Action>

== Configuration ==
Auto update enabled (auto_update_enabled): True
LED (led): True

== Debug ==
Device ID (device_id): x
RSSI (rssi): -46 dBm
SSID (ssid): x
Reboot (reboot): <Action>
Device time (device_time): 2025-07-24 12:45:51-04:00
Current firmware version (current_firmware_version): 1.0.5 Build 250306 Rel.151943
Available firmware version (available_firmware_version): None
Matter setup code (matter_setup_code): x
Matter setup payload (matter_setup_payload): MT:x

== Children ==

        == Smart Plug 1 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 0.0 W
        Voltage (voltage): 120.3 V
        Current (current): 0.0 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.0 kWh
        This month's consumption (consumption_this_month): 0.0 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>

        == Smart Plug 2 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 0.0 W
        Voltage (voltage): 120.2 V
        Current (current): 0.0 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.0 kWh
        This month's consumption (consumption_this_month): 0.0 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>

        == Smart Plug 3 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 37.5 W
        Voltage (voltage): 119.4 V
        Current (current): 0.33 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.49 kWh
        This month's consumption (consumption_this_month): 0.73 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>

        == Smart Plug 4 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 62.0 W
        Voltage (voltage): 119.9 V
        Current (current): 0.54 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.618 kWh
        This month's consumption (consumption_this_month): 0.787 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>

        == Smart Plug 5 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 0.0 W
        Voltage (voltage): 120.1 V
        Current (current): 0.0 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.0 kWh
        This month's consumption (consumption_this_month): 0.0 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>

        == Smart Plug 6 (P316M) ==

        == Primary features ==
        State (state): True
        Current consumption (current_consumption): 0.0 W
        Voltage (voltage): 119.9 V
        Current (current): 0.0 A

        == Information ==
        Auto off at (auto_off_at): None
        Today's consumption (consumption_today): 0.0 kWh
        This month's consumption (consumption_this_month): 0.0 kWh
        Overloaded (overloaded): False

        == Configuration ==
        Auto off enabled (auto_off_enabled): False
        Auto off in (auto_off_minutes): 120 min (range: 0-65536)
        Unable to read value (power_protection_threshold): 'enabled'

        == Debug ==
        Device ID (device_id): x
        On since (on_since): 2025-07-23 17:42:09-04:00
        Reboot (reboot): <Action>


root@kasapi:~/python-kasa/python-kasa# 

Today I passed the Certified Information Systems Security Professional (CISSP) ISC2 exam after 2 weeks of studying. One of my priority goals during this funemployment period was to become certified to help further cement my expertise in cybersecurity and I will share all of the resources I used in this post to help me get there this fast.

Preamble: I have 5 years professional experience working in Cybersecurity from Google, where I originally started as an IT Support lead before moving internally to become a Security Engineer.

Time commitment: I spent between 8 to 12 hours a day studying for this test over a period of 2 weeks (July 1 to July 14). I took 2 days off in between for a break on weekend days.

• Every day I completed between 50-110 questions, either via chapter domain quizzes or by using the free DestCert App on the iOS store.

Important items to consider

• Actual work experience in the field I felt to be invaluable for this exam. Many questions were related to items I had come across before in my Cybersecurity role.
• The breadth of the CISSP exam is huge and the official study guide I used to study is ~1900 pages long.
• CISSP exam is not only a technical domain test but heavily focuses on scenario based “think like a manager” style questions. Keywords like “BEST”, “LEAST”, “MOST” and “GOAL” often are indicators that your multi choice options are all likely valid answers but paying extra attention to what the question is really asking is critical for success.

My study resources and my personal rating on them:

• BOOK (9/10): ISC2 CISSP Certified Information Systems Security Professional Official Study Guide (Sybex Study Guide) 10th Edition
  • 1900 pages long, pretty dense.
  • My focus was reading each chapter summaries, at the end of each chapter there are between 100 to 150 questions specific to the security domain/chapter covered.
  • Each quiz I took I tracked on a spreadsheet with the answer I selected after skimming through chapters or watching video training content.
    • Any quiz question that I failed or got wrong, I took time to understand why I chose the wrong option on my first attempt and then I focused on understanding the correct answer from the answer key at the end of the book.
• FREE Youtube (10/10): Peter Zerger 8 hour CRAM of all CISSP domains and topics.
  • My first day studying I chose to watch close to 12 hours of video training to “set the stage” before taking the quiz questions from the study guide.
  • He focuses on the vast majority of things you need to know, but because of how condensed each domain is, some minor concepts and things I felt were missing from this… lucky for me another training course I took filled in some gaps (more below).
• FREE Youtube (10/10): 50 CISSP Practice Questions. Master the CISSP Mindset.
  • Watch this video the day before the exam to make sure your headspace on how to evaluate questions is in the right place. Remember, think like a manager based on how the question is propositioned.
• LinkedIn Learning video training and practice exams:
  • Mike Chapple (same guy who authored the study guide!) https://www.linkedin.com/learning/topics/certified-information-systems-security-professional-cissp
  • He covers some stuff I felt was missing from the CRAM videos; Chapple speaks slowly so I often played his videos at 1.25x or 1.50x speeds.
• FREE Crytography DestCert mini masterclass
  • This video does a great job at explaining crypto for the exam.
• FREE Youtube (10/10): Peter Zerger Cyber Attacks & countermeasures
  • Perfect dedicated video that covers all of the common attacks and the available countermeasures.
• (5/10) Cybrary CISSP Training by Kelly Handerhan 2024
  • I tried to use Cybrary as a complement resource prior to finding out my library gave me free access to LinkedIn learning courses, I did the first 2 domains videos and wasn’t personally impressed.

How I hacked my study plan?

1. I used AI / ChatGPT / Perplexity to help me understand certain topics or when I needed concepts explained to me in a different way or tone than the book or videos.
2. I practiced every day. Domain quizzes using DestCert app while on the treadmill or when sitting down at the computer I would do more questions from the study guide book which are different questions than the DestCert app btw.
3. I put a deadline to it and chose to go all-in (vs. studying for months). Pay the extra $200 to get “peace of mind” protection in case you may fail your first attempt, I passed on my first try but this exam is tough and things could have easily gone the other way had I not been studying this much.
4. The most important thing during the test: TAKE YOUR TIME, READ THE QUESTION AND ITS OPTIONS MULTIPLE TIMES before committing to any answer.

Good luck!

As I write this I realize the last post I made here was on April 30, 2023 which is over 2 years ago and being honest with myself I haven’t been the most active at keeping this site updated due to being busy with career/life and posting content elsewhere like Github.

As of July 2025 I now have some time to work on hobby things like this blog and self-improvement goals like obtaining the CISSP certification (Certified Information Systems Security Professional). Taking a break after 10 years at Google and looking forward to see what’s next on my career journey.

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• https://www.domnest.com/
• https://www.domcomp.com/
• https://tld-list.com/

Resources to find cheap storage servers

• https://www.serverhunter.com/
• https://oneprovider.com/promotion