from the net: 20 Daily Linux Commands System Administrators Use in Production

 As a Linux SysAdmin working in a production environment, your daily routine is all about keeping systems stable, secure, and performing at their best. From troubleshooting issues to monitoring resources and ensuring uptime, you wear many hats, and time is always of the essence.

While Linux offers thousands of commands, not all of them are part of your day-to-day toolbox. However, there’s a core set of powerful, reliable commands that you’ll find yourself using every single day, often multiple times.

In this article, I’ll walk you through the 20 most essential Linux commands every system administrator should master. These aren’t just commands, they’re your go-to tools for monitoring performance, managing logs, controlling services, debugging problems, and much more.

CLICK THE IMAGE FOR THE FULL ARTICLE

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I have some ideas for some cool challenges and giveaways in the new year which will only be available to email subscribers.

Boost Your Packet Analysis with the CellStream Wireshark Profiles Repository

For network engineers, security analysts, and IT troubleshooters, Wireshark is an indispensable tool for inspecting packet-level traffic and diagnosing complex issues. But despite its power, setting up Wireshark just the way you need it — with the right filters, color rules, columns, and display preferences — can take a lot of time. That’s where the CellStream Wireshark Profiles Repository comes in: a centralized collection of ready-to-import Wireshark configuration profiles that streamline setup and make pinpoint analysis faster and easier. 

CellStream, Inc.

One of the biggest advantages of using pre-built Wireshark profiles is time savings. Instead of manually crafting display filters and custom views for each protocol or troubleshooting task, you can simply download and import a profile tuned for a specific purpose — whether that’s DNS analysis, Wi-Fi troubleshooting, IPv6 focus, VoIP flows, or TCP performance insights. These profiles come with optimized configurations that reflect real-world use cases, helping you spend less time configuring the tool and more time diagnosing issues. 

CellStream, Inc.

In addition to speeding up your workflow, the repository helps users learn best practices. By exploring profiles created by experienced network professionals, you can see how seasoned analysts structure filters, choose color rules, and organize columns for maximum clarity. This makes the repository not only a practical resource but also a learning platform — especially for those new to Wireshark or looking to develop deeper packet analysis skills. Furthermore, having a variety of profiles lets you quickly switch between different analysis contexts without losing your custom settings. 

CellStream, Inc.

Finally, the CellStream repository fosters community collaboration and sharing. While the collection is curated to avoid unsafe uploads, contributors can submit improved or new profiles to expand the library for everyone’s benefit. This collaborative aspect turns a typically solitary configuration task into a shared resource, empowering the wider Wireshark community with tools that reflect a broad range of networking needs and real-world scenarios.

click on the image and go check it out

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When Your Tools Don’t Agree: The Ubiquiti Wave Pro Headache

There’s nothing quite as frustrating as trusting your monitoring tools—only to find out they’re telling two completely different stories. That’s exactly what happened during a recent Ubiquiti Wave Pro deployment. I was working the install remotely, checking the unit through the web interface, when it suddenly showed the 60 GHz link as down. Naturally, that set off alarms. A down link means troubleshooting, delays, and a big headache. But then I got a message from my onsite tech saying, “Everything looks fine here—the link is up.” That contradiction alone was enough to make me question my sanity.

At first, I assumed it had to be a syncing issue or maybe a firmware glitch. But the odd part was that the Bluetooth app on-site was showing completely different information from the web interface. Two official ways to access the exact same device—and somehow they couldn’t agree on something as fundamental as link status. When you're depending on accurate remote visibility to keep things moving, this kind of mismatch isn’t just inconvenient—it’s a recipe for wasted time, unnecessary troubleshooting, and serious deployment delays.

So, I tried to open a ticket with Ubiquiti support, expecting at least a “try this” or “here’s a workaround.” Instead, their response was almost surreal: they openly admitted it’s a known issue with no ETA for a fix. Not a minor bug, not a cosmetic glitch—an outright discrepancy between their own interfaces on critical link status. Even the support chatbot echoed the problem, saying, *“Based on your description, there may be a discrepancy between what UISP and the radio’s web interface report versus the Bluetooth app.”* It then pointed me to a general WiFi optimization guide that had nothing to do with the issue at hand.

In the end, the whole experience left me shaking my head but at least i knew it was a bug. When you're deploying gear like the Wave Pro, accurate diagnostics aren’t optional—they’re essential. Having to second-guess the device’s own interfaces shouldn’t even be on the table. Until Ubiquiti sorts this out, anyone managing Wave Pro deployments will need to rely heavily on onsite checks, because the remote view just can’t be trusted. It’s disappointing, avoidable, and honestly, not what I expect from equipment at this level. 

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The next outage is coming – is your organization prepared?

Click the image for the article

Blast from the past - The Unidisc

 

The disc is metal and the whole thing weighs 2.9 kg (6 lbs, 6 oz) and stored 2 MB in 1996.

If you were a computer enthusiast in the late 1970s or early 1980s, you may remember **The Unidisc**, a quirky but clever attempt at solving one of the era’s biggest headaches: incompatible disk formats. Back when every computer manufacturer believed their floppy disk system was the one true path to digital enlightenment, The Unidisc showed up like a universal translator for storage media. Designed to read and write multiple floppy formats, it became a surprisingly essential gadget for anyone juggling CP/M machines, early PC clones, or that one weird computer your uncle bought from a mail-order catalog. One lesser-known bit of trivia is that The Unidisc often found itself used in small businesses that were transitioning from older dedicated word processors to microcomputers. Rather than retyping mountains of documents—a fate worse than dial-up speeds—they used The Unidisc to transfer data from one platform to another. In an era before USB flash drives, cloud sync, or even reliable networking, this thing was basically the Swiss Army knife of floppy drives. And like any Swiss Army knife, half the time you didn’t know what all the tools did, but you were glad they existed anyway. Another fun fact: enthusiasts still mention The Unidisc in retro-computing forums today, usually followed by a story that starts with “You won’t believe what I found in a box in my parents’ basement…” Many collectors swear by its durability—remarkable considering that modern gadgets beg for a protective case just to survive a gentle breeze. The Unidisc, on the other hand, seems to have been built out of the same material used for 1980s school desks and indestructible lunchboxes. You could drop it, stack things on it, or ignore it for 25 years, and it would probably still spin up. Of course, the true charm of The Unidisc lies in its accidental comedy. It promised “universal compatibility,” which was ambitious for a world where every company wanted proprietary everything, down to the screws. Using it sometimes felt like convincing rival kingdoms to sign a peace treaty—magnificent when it worked, mildly tragic when it didn’t. But when that clunky, glorious machine actually transferred your files without arguing, it felt like magic. Today, it’s a delightful reminder of a time when “plug and play” was more like “plug and pray,” and every working data transfer felt like a small personal victory.

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from the net: Aisuru botnet behind new record-breaking 29.7 Tbps DDoS attack

 

In just three months, the massive Aisuru botnet launched more than 1,300 distributed denial-of-service attacks, one of them setting a new record with a peak at 29.7 terabits per second.

Aisuru is a huge botnet-for-hire service that provides an army of routers and IoT devices compromised via known vulnerabilities or through brute-forcing weak credentials.

Internet management and infrastructure company Clou...

click the image for the full article

Linux cp command reference sheet

 

Technical cheat sheets are one of those things you don’t truly appreciate until you’re knee-deep in a problem and need the right command right now. When you’re working with Linux—especially with command-line utilities like cp—even seasoned pros can blank on syntax or flags. A good reference sheet acts like a mental shortcut, giving you instant access to the commands you use often, the ones you occasionally need, and the obscure options you’ve inevitably forgotten. Instead of digging through man pages or searching the web, you have the essentials neatly distilled into something you can scan in seconds.

Beyond convenience, cheat sheets dramatically cut down the cognitive load of technical work. Linux commands tend to pack a lot of functionality into short syntax, and remembering every flag (-r, -v, --parents, --no-clobber, etc.) isn’t a realistic expectation—especially when you're switching between tasks all day. A good cheat sheet reduces that mental juggling. It lets you focus on solving the actual problem instead of second-guessing whether you’re about to overwrite the wrong directory or miss a crucial flag that changes behavior. That reduction in friction adds up to faster, more accurate work.

There’s also an incredible amount of invisible effort that goes into creating a solid technical reference sheet. Anyone who has made one knows it’s more than “just jotting down commands.” You have to test each use case, verify edge behaviors, compare different versions of the command across distributions, and decide what’s essential enough to include. It’s a balance between completeness and usability. Too little info, and it’s pointless. Too much, and it becomes another overwhelming document no one wants to use. Curating clean, reliable, concise technical guidance takes real time, technical depth, and often several iterations.

Finally, cheat sheets become valuable assets not just for the person who creates them, but for entire teams. They help standardize how tasks are performed, reduce onboarding time for new staff, and minimize errors caused by inconsistent knowledge. When dealing with something as powerful—and potentially destructive—as Linux file operations, having a tested and trusted reference isn’t just handy; it’s a safeguard. The payoff is huge: smoother workflows, better accuracy, and a more confident technical environment. In short, technical cheat sheets are small tools with big impact.

Just click on the image to get the full screen view

From Dan Nanni www.study-notes.org

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Yup, we're on Facebook, 

https://www.facebook.com/groups/24900262876244964

📌 Packet Bookmarks in Wireshark: The Shortcut You Didn’t Know You Needed

 

When you're staring at a firehose of packets in Wireshark, trying to find that one moment in a chaotic capture can feel like decoding ancient hieroglyphics. That’s where packet bookmarks—or more accurately, sending a deliberate “ping” or identifiable packet during a trace—comes in clutch. By injecting a unique packet into the capture at the right moment, you create a visual anchor that helps you quickly zero in on the part of the traffic you actually care about, instead of scrolling endlessly like you're searching for lost treasure.

This technique is especially handy during live troubleshooting. Let’s say you’re working with a remote user and need to isolate when they clicked something, recreated a bug, or triggered a specific network event. Instead of guessing, you have them run a quick ping or curl command right when the issue occurs. That injected packet shows up as a bright, unmistakable blip in the capture. Once you find it, you’re instantly transported to the exact section of packets you need to analyze—no more hunting through thousands of frames by timestamp alone.

It also helps when multiple engineers are involved. If you're collecting captures from different vantage points—client, server, firewall—you can have everyone trigger the same “bookmark” moment. Later, when comparing traces, those bookmarks become synchronization points. This makes aligning timelines between captures a breeze and eliminates those awkward moments where you're trying to figure out why the client’s clock is three minutes off from the server’s.

Ultimately, packet bookmarks are simple, fast, and surprisingly powerful. They don't require any special Wireshark features or advanced filters—just a strategically injected, recognizable packet. Next time you're taking a trace, throw in a deliberate ping or custom packet at key moments. Your future self, scrolling through a mountain of traffic at 2 AM, will thank you.

Enjoy

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Better Wi-Fi for the Hospitality Industry from Ekahau

from the web: CISA Reports PRC Hackers Using BRICKSTORM

 

CISA Reports PRC Hackers Using BRICKSTORM for Long-Term Access in U.S. Systems

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Thursday released details of a backdoor named BRICKSTORM that has been put to use by state-sponsored threat actors from the People's Republic of China (PRC) to maintain long-term persistence on compromised systems.

click on the image for the full article

⚠️ “Copy, Paste, Pray” — The Totally Foolproof Way to Break Everything with AI-Generated Code

There’s nothing quite like the thrill of blindly copying and pasting code from an AI model and expecting it to work perfectly on the first try. It’s the modern equivalent of buying furniture from Ikea and assuming you won’t have any screws left over. Recently, I decided to let Google AI craft a simple PowerShell script to SSH into a server and run a couple of simple commands.

 In theory, an easy task. In practice? It went about as well as trying to start a campfire with wet spaghetti.

At first glance, the script looked like it whispers, “Trust me, I know what I'm doing.” So naturally, like any responsible tech professional, I copied it, pasted it, hit Enter, and waited for magic. What I got instead was a spectacular combination of syntax errors, modules that apparently only exist in another dimension, and authentication failures so dramatic that I’m pretty sure the server judged me personally. The script didn’t “execute” so much as it “flopped politely.”

As I debugged the digital Picasso it had produced, I realized the script wasn’t even using real-world PowerShell SSH practices. It had invented its own syntax, mashed together three different module styles, and confidently referenced a function I’m 99% sure was made up on the spot. It’s like the AI had the right vibe of a script, but none of the actual functionality. Meanwhile, Google AI sat there proudly like, “You’re welcome,” while I manually rewrote the whole thing like a disappointed parent fixing a child’s science fair project made out of duct tape and crayons.

So here’s the moral of the story: AI code suggestions are great for inspiration, terrible for production, and absolutely perfect if you enjoy chaos. Don’t blindly trust them. Verify, test, tweak, and for the love of uptime, don’t assume they actually know how PowerShell works. Otherwise, you too may find yourself arguing with a server because you copy-pasted code written by a very confident, very imaginative robot author who has clearly never SSH’d into anything in its life.

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Blast from the past: Another expert prediction

 another expert prediction

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Kali Linux - The Interfaces

I was pleasantly surprised with the positive response from my first Kali video which covered simply updating Linux https://youtu.be/8GDEhxZB1nY. If you intend to use Kali, I strongly recommend you ensure everything is current.

A few people asked why I bothered with such a basic video and the answer was simple, I had people ask for it.

Much like this next video; a comment that was typically thrown out when people start Kali Linux and want to use Wireshark or tshark is, “Now what?”.

So in this short video, I will show you how to determine which interface index you will use for tshark , the interface name for Wireshark, and how to put Wireshark on your desktop.

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The Unsung Hero of Install Day: Ubiquiti Wave Pro’s Cable Test Feature

 

When deploying a Ubiquiti Wave Pro wireless link, one of the most underrated yet invaluable tools is the built-in cable test feature. Before you even start the alignment process, running a cable test instantly tells you whether your physical layer is solid. It verifies continuity, checks for shorts, measures cable length, and identifies pair-swap or split-pair issues—problems that can easily go unnoticed until they start causing intermittent drops or throughput issues in production.

During field installations, especially when working on towers, rooftops, or remote sites, this feature saves both time and headaches. Instead of hauling an external cable tester, climbing up and down ladders, or guessing whether the issue is the cable or the device, you get immediate diagnostics right from the Wave Pro interface. This is especially handy when working with long outdoor-rated runs, where damage can occur from bends, staples, or environmental wear.

The cable test feature also acts as a quality check for contractor-run cabling. Before you sign off on their work or attempt to troubleshoot connectivity, you can quickly validate that the copper infrastructure meets spec. It eliminates finger-pointing and ensures you’re not trying to push gigabit speeds over a mis-terminated connector or poorly run segment.

Most importantly, it gives you confidence during deployment. Knowing your cable is good means one less variable to worry about when aligning radios, optimizing throughput, or diagnosing link issues. In the fast-paced world of wireless networking, the Ubiquiti Wave Pro’s cable test feature is a simple but powerful tool that helps ensure smooth, efficient, and reliable installations every time.

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Crimp, Click, and Connect: Building a Custom Outdoor Ethernet Cable from Scratch

There’s a certain satisfaction in crafting your own Ethernet cable—especially when it’s built to last in the great outdoors. I recently purchased a complete RJ45 kit from Amazon that came with everything I needed: connectors, protective boots, a crimper, and a compact cable tester. Instead of relying on pre-made patch cords, I decided to put the kit to the test using a roll of outdoor-rated Ethernet cable, built tough for weather and UV exposure.

The process started with stripping the cable’s jacket to expose the twisted pairs inside. The outdoor cable had an extra layer of protection, so patience was key to avoid nicking the inner wires. Once I had the pairs separated, I followed the T568B wiring standard, arranging the wires in the correct color order before sliding them into the RJ45 connectors. A firm squeeze with the crimper locked everything into place, ensuring solid contact between each wire and its pin.

Next came the boots—those little rubber sleeves that make the cable look professional and protect the connectors from wear. Once the boots were on, I plugged both ends into the cable tester that came with the kit. The LEDs lit up in perfect sequence, confirming that every pin was connected correctly and that my cable was ready for use. It was a small victory, but a satisfying one.

By making my own Ethernet cable, I not only saved money but also gained a deeper appreciation for the craftsmanship behind reliable networking connections. With the Amazon kit, even a simple task like crimping connectors turned into a fun, hands-on learning experience. Now I have a durable, custom-length outdoor cable I can trust—made by my own hands.

https://youtu.be/B_ufDL3hY6E

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from the net: Networking with Python

 

Another cool sheet from Dan Nanni at www.study-notes.org

Filter Like a Pro: How Wireshark Display Filters Save You Hours of Headaches

 If you’ve ever opened Wireshark and stared at the endless flood of packets flying across your screen, you know it can feel like trying to find one drop of water in a waterfall. That’s where display filters come in. Learning how to use Wireshark display filters — especially for things like narrowing traffic down to a specific IP subnet — is like flipping on a spotlight in a dark room. Instead of drowning in packets, you can instantly zero in on exactly what matters.

In my latest video, I walk through how to create and use a display filter for an IP subnet. This simple trick saves tons of time when troubleshooting network issues. Instead of scrolling endlessly or exporting data to another tool, you can just type something like ip.addr == 8.8.8.0/24 and immediately see all the relevant packets for that network. It’s fast, it’s clean, and it keeps you focused on solving the problem instead of searching for it.

The more you get comfortable with display filters, the more powerful Wireshark becomes. You can combine filters, exclude noisy traffic, or even isolate specific conversations between devices. Once you start using them, you’ll wonder how you ever managed without them — it’s like going from a shovel to a laser scalpel for your packet analysis.

So, if you’re looking to save time and actually enjoy using Wireshark, start learning display filters today. They turn what could be hours of frustration into minutes of precision. Check out my video to see exactly how I use an IP subnet filter in action — and you’ll never go back to staring at unfiltered chaos again.

Nailed it.. ;) - an Exercise in supporting our colleagues

 An excited reader sent this photo.

Since he is new to the field, i had to politely and constructive explain all the ways to 'make this install better'.

after an email or two, i could se that he was pretty laid back and i casually said "other than that one grey cable, you nailed it" and we have a good chuckle..

I also mentioned that no matter what, you can never have enough documentation and labels.

I finished off by saying "put yourself into troubleshooting mode, and ask yourself how easy it would be to trace a cable" ,  "then put yourself into installation mode and ask yourself how easy is it to install a new piece of equipment".

He thanked me for being an "awesome mentor".

I replied that I dont consider myself much of a mentor but appreciated the kind words.

And then he mentioned something that was a bit disturbing to me.  He said that he reached to about half a dozen people who post on Linkedin/Youtube and I was the only one who responded.

C'mon folks, we can do better.  I know we are all busy..  But it doesn't take much for a quick response, even if its "I don't know, but try this".  this email exchange took about 10 min of my day.

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From the net: How to Simulate Network Outages

Simulating network outages is an important step in validating highly available and/or redundant network configurations. Along with validation, another use case for simulating network outages is to test the resiliency of mission-critical systems and applications. The simplest example of a test-driven network outage is to turn off the primary uplink connection of a dual-homed router and analyze the results. With appropriate tools, you can verify that the network traffic quickly re-converges to the secondary link with minimal packet loss. In more complex scenarios, the network simulation may need to introduce packet loss, increase in round-trip time, bandwidth saturation, DNS and DHCP failures. To implement these failure scenarios there are different tools that can do the job. I’ll briefly review some of them, particularly the open source solutions.

Click on the logo to read the post

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One of the best giveaways that I've ever received. 

From our Wireshark/Profitap class a while back https://packetguru.com/ 

Thanks John

Rii RK100+ Multiple Color Rainbow LED Backlit Large Size USB Wired

Why Every IT Troubleshooter Should Carry a Portable LCD Display

 

When you’re deep in the field troubleshooting hardware or network equipment, one tool that often goes underappreciated—but can save the day—is a portable LCD display. Many devices such as servers, switches, or embedded systems output critical data or BIOS messages directly to a display, and without one on hand, you might find yourself blind to what’s really happening. A compact LCD lets you instantly see console outputs, error codes, or configuration prompts without waiting for someone else to bring one or trying to guess what the LEDs are telling you.

Portability is the key advantage here. Modern LCDs are lightweight, slim, and powered through USB or battery packs, making them easy to slip into your toolkit or backpack. When you’re on-site, especially in tight server rooms or industrial areas, you don’t have the luxury of hauling a full monitor around. Having your own display means you can plug in, verify, and get results fast—whether it’s a headless system, a router with a misconfigured interface, or a piece of lab gear showing diagnostic information.

Carrying your own display also means independence and preparedness. You’re not relying on the client’s equipment or waiting for someone to find a monitor in a dusty back room. You can confirm system states, troubleshoot POST issues, and even make quick BIOS or bootloader changes on your own terms. It’s a small investment that pays off big in time saved and professionalism demonstrated.

In short, a portable LCD display transforms how you handle unknown or unresponsive systems. It’s like having an extra pair of eyes in your toolkit—ready whenever the situation turns unpredictable. Whether you’re configuring switches, diagnosing embedded devices, or recovering from boot failures, this one tool keeps you in control and keeps your troubleshooting momentum going strong.

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from the net: Linux Grep

 Everyone loves a reference sheet and this one is very helpful since GREP is so under utilized

 

Found this on www.sysxplore.com

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my favorite mouse - click on the image for more info

Logitech M720 Triathlon Wireless Mouse, Bluetooth, USB Unifying Receiver, 1000 DPI, 6 Programmable Buttons, 

-20% $36.08

List Price: $44.99

blast from the past: The IBM 3800 Laser Printer

 

The IBM 3800 Printing System, introduced in 1976, was a landmark in computer printing technology and is often regarded as the world’s first commercial laser printer. Designed primarily for high-volume data centers, the 3800 combined a laser imaging system with electrophotographic technology (similar to photocopying) and continuous-form paper feeding. It could print at an impressive rate of 20,000 lines per minute—roughly equivalent to 110 pages per minute—making it a revolution in automated document generation for large organizations like banks, insurance companies, and government agencies.

When it first launched, the IBM 3800 came with a hefty price tag. Depending on configuration and options, the system cost between **$250,000 and $500,000 USD** (equivalent to over $1 million today). However, IBM typically leased such machines to clients rather than selling them outright. This business model made sense for large-scale enterprise operations that required regular maintenance, consumables, and software integration. The printer’s cost was justified by its efficiency—it could replace multiple impact line printers and drastically reduce downtime and operating costs in large-scale print operations.

The 3800 also introduced several important innovations in digital printing. It was the first printer to take input directly from digital computer data, rather than relying on preformatted line print files, allowing for dynamic page layout and improved typographic control. The printer supported fonts and graphics stored in memory, a feature that paved the way for later desktop laser printers in the 1980s. Its use of continuous-form paper and integrated fuser technology made it highly reliable for round-the-clock operation, which was essential for industries producing daily billing statements or reports.

As for trivia, the IBM 3800 was so large it required its own dedicated room and environmental controls—it resembled more of a small car than a modern printer. It was also one of the first machines to use a **laser beam controlled by computer logic** to create images on a photoconductor drum, a concept that later became standard in laser printing. IBM continued developing the series through the 1980s, leading to successors like the 3800 Model 3, which improved resolution and reliability. Interestingly, some units remained in use well into the 1990s, a testament to their engineering quality and durability. The IBM 3800 is now remembered as the ancestor of modern laser and page printers, marking a major milestone in the evolution of digital printing technology.

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one of my favorite portable keyboards