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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