Robert Olejnik

Simple SMS tool (using ModemManager)

2025-07-31T00:00:00+00:00

I’ve searched in many places for a tool to handle SMS messages (sending, receiving, …) using ModemManager - but couldn’t find one, so I wrote a quick and dirty Bash script that does so. I have a failover setup for my main internet provider using an LTE modem and found it very useful to have a mobile number available for sending SMS alerts when server errors occur, such as:</p>

no internet connection — sending status updates about the failover</li>
sending messages about modem restarts and so on…</li> </ul>
Here it is: github.com/teon/sms</a></p>

AI, the trend exposing SaaS privacy fraud - why am I self-hosting my services

2024-12-05T00:00:00+00:00

It’s mostly about privacy and trust. To share your private data, you need trust, and I never trusted big SaaS companies. I know that’s uncommon in this age when either everybody shares everything, or where the Internet gives the illusion of anonymity. But I know here are a lot of conscious people, longing for privacy and digital freedom - that’s why I’m sharing my thoughts - especially now, where they</em> exposed their true nature.</p>

AI - the trend, exposing the service providers privacy fraud</h2>
I’m really happy about the AI trend - as it helped a lot of people to understand the thing that is obvious, but somehow was not?! you need to control your data for them to be private</em>.</p>
How’s that you ask?</h3> No individual is physically capable of following and understanding (in legal terms) constant changes in terms of conditions and privacy policies. Companies always used that for their gains, but the most recent trend is not a threat but direct violation not only of privacy and trust, but literally of property rights. There are notorious cases (see my blog-post following a lot of them here</a> that services are using your data to train their AI. If you do not understand the severity of the issue, let me put it in other words: individuals and companies pay for a service that uses their own data to develop their automated competitors (AI algorithms)</strong>. There is a clever way of defense from those companies: you can always opt out</em>. But the fact is - before opting out, all your current data was most probably already used - and you just can’t do anything about it</strong>.</p>
Just think about this for a moment, if some technology trend convinced companies to just take your data for their gains - was there ever any privacy to them? Can you actually trust any service provider?</strong></p>
I know there is a real problem for a “normal user”, not capable to spin off a home-lab and deploy their own services, but we - the IT gave the trend the permission to skyrocket and be a thing</strong>. We, for our convenience choose cloud and SaaS in our companies, fueling these trends - and not the trend of building easy to use, deploy and integrate privacy focused solutions, which would flourish if more companies just preferred to be private - and put the effort in binding such solutions (and not patchworks for cloud to be even bearable).</p>
What can I do? What can you do?</h2>
1. Open Source</h3>
Use open source solutions. If not self-hosted/on-premise at least use and recommend to “non-it” people services based on open source solutions.</p>
Building trust is much much easier with open source solutions, where not only the code is open, but also the project governance and communication (with the users and in a lot of cases also internal within the development team). It’s completely the opposite of any SaaS/solution provider which guard everything, promise and do marketing instead of just being transparent.</p>
Also, there are the great communities - where thousands (or millions) of like-minded users guard and look for red flags constantly…</p>
2. Self-host</h3>
I’m so genuinely happy to see the self-hosting to gain more and more momentum. This fuels the new trend, that’s it’s worth to build open source solutions and services based on open source solutions.</p>
Self-hosting is also important, as we - the enthusiasts help the individuals and companies building open source solutions to be better</strong> - with our feedback, contributions or just spreading the word.</p>
3. Build open source!</h3> I’m self-hosting all my personal and company solutions (and data) from beginning of my time</em> (which is mid 90’s). I’m also a hardcore Unix and Linux user (since kernel 1.x.x and Slackware 3.x) and have been developing my first open-source project in the early 2000s</a> - but as a way of living, I struggled heavily to understand the open source business model and stayed in the service business for almost 20 years.</p>
Do I understand it now? I’m trying</a> - so if you have more experience than me and are willing to chat reach out please!</a>.</p>

Intuition quantified!

2024-11-03T00:00:00+00:00

The pursuit and search for quantifying and deeply understanding intuition</a> is over! It gets better, Graham Weaver</a> not only explains it spot-on, but he also provides an easy-to-understand, implementable process for going deep on intuition. Here it is:</p>

</iframe></div>
Video</span>Graham Weaver on going deep on intuition</span></figcaption> </figure>

What is life?

2024-10-20T00:00:00+00:00

I love to journal – I’ve been doing it every day for nearly 10 years now</strong>.</p>
Most of the time, I’m recording my thoughts or just talking to myself</em>. It’s a remarkable tool that teaches patience, clear thinking, and observation. That last part (observation) I’ve recently started to cultivate in a new way, which forces me to summarize my observations in short form.</p>
Here’s one of them:</p>
“Life is a constant search for the right changes that will evolve into consistently cultivated standards and rituals.”</em></p>

What is intuition?

2024-08-10T00:00:00+00:00

2024.11.03 Update</h2>
Here is what I’ve actually been looking for!</a></p>
The best decisions in my life, business, and health were made by listening to my intuition. But what is intuition?</p>
It’s a feeling</em> that is really hard to explain, and I’ve found that the best way to do so is by example—through one’s actions (taken under that “feeling”) and the consequences of those actions. However, this is subjective and hard to describe.</p>
When working with my teams, I often encourage people to listen to their intuition, but I didn’t have a good go-to reference</em> or examples that would encourage</strong> anyone to put in the really hard work of finding their own inner voice.</p>
A Good Example</h2> I’ve stumbled upon a really interesting conversation</a> between Rich Roll</a> and Light Watkins</a>, where all examples given by Light and all explanations about the inner voice</em> are the best explanations (and good examples) about intuition</strong> I have ever heard:</p>

</iframe></div>
Video</span>Rich Roll and Light Watkins on the inner voice</span></figcaption> </figure>
Although I do not agree with some other statements in that conversation (like: you actually don’t own anything in your life</em>), I would still encourage anyone to listen to it.</p>

My first sabbatical

2020-06-12T00:00:00+00:00

I have been working professionally since the middle of high school - 20+ years. Since then, I have not had a vacation longer than 2 weeks - and those I have started to take fairly regularly just around 5 years ago.</p>
But I have never had a real (doesn’t matter how long) sabbatical from work. I didn’t even have this idea in my mind, that you can have a sabbatical (not vacation) until I listened to an interview by Tim Ferriss with Jerry Colonna</a> - where the guest makes a great case for two/three month sabbatical (highly recommended listen).</p>
Update:</strong></p>
Another Tim’s guest</a> Matt Mullenweg, makes a case for it</a>, also pointing that Automattic has a sabbatical benefit</a>.</p>
I have decided to do it.</h2>
And here was my reasoning pre-sabbatical - since (if you are a workaholic), you need a good justification for that nuclear bomb heading your way:</p>

I just need it - I owe it to myself for 20+ hard years of work. And if you run a company (or two, or seven 😂)</a> you know that it’s not typical work - it’s 24/7.</li>
This will actually be good for business. We will test if all systems, policies, and people are in the right place, to have a sustainable business, and not have bus factor</a> == 1 (meaning dependent on me).</li>
I just have a long overdue private to-do list, and that needs to be done someday, right? Right??? 😵</li> </ol>
I’ve done it.</h2>
So here is a recap:</p>
The important stuff</h3>

We had a few days hike with my oldest son (which I’ve been promising for 2 years). It was just spectacular! Just that made me realize - why am I working for (whom). </li>
Learned how to properly service a bike and built my own home bike service/shop.</li>
Learned that bike-packing is a thing, and built my own setup, and did a lot! of solo bike rides. </li>
Did a few day solo-hike in Saxon Switzerland</a> (both Czech and German side). </li>
Spent some time in Berlin, finally seeing Museum für Naturkunde Berlin</a> and Computer Games Museum</a> (highly recommended).</li>
Did a few great bike trips with my friend (and one of teonite’s</a> partners) Kamil: </li>
Did a whole day meditation session and a few days just contemplating life =]</li> </ol>
Projects rabbit hole</h3>

Tested various blogging/static site generators and implemented this blog site with Zola & Custom Paper theme.</li>
Implemented in home & private office proper IoT VLANs with Homebridge for AppleHome devices.</li>
Did a lot of research about the security of various chat protocols (Telegram, Signal, …) and decided that my preference will be Matrix</a> - and implemented my own Matrix server.</li>
Implemented my own mail server with mailcow</a> - finally! I host my own private email.</strong></li>
Migrated 100Gb+ mail from various Google Workspace/Gmail accounts into my own server (and Google workspace) - that for sure will be another blog post.</li>
Implemented a proper backup system with Restic</a> (and Rustic</a>) and ansible setup.</li>
Implemented a proper multiple YubiKeys setup</a>, with cold storage of master keys.</li>
Tested a lot of pocket</a> self-hosted alternatives and implemented my own Hoarder</a> instance.</li>
Tested a lot of Google Analytics alternatives and implemented Plausible for my sites.</li> </ol>
Reading</h3>
Finally caught up with my (Fresh)RSS feed - with some of my favorites - especially Derek Sivers</a>, Bunny</a>, Ma.tt</a>. I’ve also discovered Andreas Klinger’s</a> blog with priceless advice about managing a team, investment, startups (and more!). A lot of what he’s writing I have observed in my 20+ year career as a manager, investor, and product builder but a lot of insights were new to me - and pure gold! My goal is to read all those important blog posts at least once a month for some time until it will be in my “blood”.</p>
Standout book I’ve read: Derek Sivers - How to live</a>.</p>
Closing thoughts</h2>
I think this is one of the greatest gifts I’ve given myself</strong>. It gave me perspective, a lot of personal insights (as well as new ideas and perspectives towards business) but also made me appreciate everything I have, do and did up to this point - much, much more.</p>
I was also very delighted to see that some of my peers did actually miss me 🤣 and to hear that it’s good that I’m back 😍.</p>

Homebridge with Avahi on VLAN networks

2020-05-24T00:00:00+00:00

I have an IoT network (for devices) running on a dedicated VLAN (with a hardened firewall of course! ;-)) and a Homebridge</a> instance, that exposes some of those devices in an Apple Home (since they do not support iOS HomeKit API by default).</p>
Now the problem is that for Apple Home to work:</p>

Homebridge needs to have access to both local network and IoT VLAN.</li>
There needs to be a solid mDNS Advertiser</a> that also runs on both networks.</li> </ul>
After researching various advisors, I found that having a local Avahi</a> daemon (on the same server that the Homebridge is running) is the best solution, since it’s easy to limit and configure which networks it should listen on (allow-interfaces</em> - and choose only VLAN and local network), but I’ve spend hours debugging why this setup isn’t working!</strong> Avahi and Homebridge ‘saw’ the devices, but I couldn’t control them from my iPhone, thinking that my firewall and setup were too restrictive.</p>
The solution to this problem was this configuration line in /etc/avahi/avahi-daemon.conf</code>:</p>
[reflector] enable-reflector=yes </code></pre> This enables Avahi to propagate mDNS records for devices on the VLAN network to the local network, making them visible to Apple Home (or generally available to be discovered in the ZeroConf network).</p>
UniFi hack: prefered 2.4GHz network for low 5GHz signal 2020-05-23T00:00:00+00:00 The problem</h2> I have an IoT network (for devices) with the same SSID enabled on both 2.4GHz and 5GHz bands, as some devices are not capable of handling 5GHz. Some devices, which are further away from the AP, can handle both 2.4GHz and 5GHz networks. However, they constantly switch between 5GHz and 2.4GHz depending on the signal conditions. I have Band Steering set to prefer 5GHz, and I would like to keep it that way. So, how can I force those devices to use 2.4GHz?</p> Simple solution</h2> I have been diging UniFi forums, reddit and couldn’t find any solutions, so I came up with this:</p> Check on the device (which is switching between networks) to see what the maximum RSSI level is for the 5GHz network.</li> Go to UniFi Network Panel -> Devices -> Select the Access Point (that those devices are using) -> Settings.</li> In the 5GHz network section, turn on ‘Minimum RSSI’ and select a value that is higher than the maximum signal that those devices get.</li> </ol> </p> Now, since that device has a lower RSSI than set, it will automatically be steered to the 2.4GHz network and will stop switching between networks</strong>.</p>

Robert Olejnik

Simple SMS tool (using ModemManager)

AI, the trend exposing SaaS privacy fraud - why am I self-hosting my services

Intuition quantified!

What is life?

What is intuition?

My first sabbatical

I’ve done it.</h2> So here is a recap:</p>

Projects rabbit hole</h3> Tested various blogging/static site generators and implemented this blog site with Zola & Custom Paper theme.</li> Implemented in home & private office proper IoT VLANs with Homebridge for AppleHome devices.</li>

Homebridge with Avahi on VLAN networks

UniFi hack: prefered 2.4GHz network for low 5GHz signal

I’ve done it.</h2>
So here is a recap:</p>