CellStream, Inc. – Telecom Consulting and Training! 3-Day Instructor Led Hands On Lab Class Available in either Web Based delivery or On-Site Delivery Minimum 10 students – Maximum 16 students What Students are Saying About this Class: “[Instructor] covered the information incredibly well and all of it was applicable […]
CSI-HO-036 – L1, L2, and L3 Networking Protocols – 3 Day Hands On Lab Course Read More »
If you have been to one of my Wireshark or Wi-Fi classes then you know I often criticize Microsoft Windows for some of its – well – inexplicable approaches to usage and security. Here is yet another example. Windows stores several important pieces of information in Wi-Fi profiles to facilitate automatic connections to known networks
Find and Display All Your Wi-Fi Passwords in Windows Read More »
Scenario Let’s say you have a DHCP server running on a Cisco Switch that is behaving strangely and you want to examine the traffic over a couple of hours while not creating a gigantic unmanageable capture file. A note here: I am doing this on a Cisco switch, but most all vendor switches support this
Troubleshooting Your Network Using Port Mirroring and Packet Capture Read More »
In this article, I wanted to provide a guide to using ping – ICMP Echo – to troubleshoot your network. Most people use ping on their platform to test if they can reach a given destination. Just open up a terminal (Linux or MAC OSx) or command line (Windows: Start> Run> cmd) and enter the
Troubleshooting The Internet Using Ping (a.k.a. ICMP) Read More »
In a recent class I was asked for some details on BGP Autonomous System (AS or ASN) Numbers. I thought I would document and provide a more complete answer here for others to learn from as well. What is the AS Number? Let’s begin with a definition. An Autonomous System Number (AS number or simply
BGP Autonomous System (AS) Numbers Read More »
In this article I want to visit a “not used enough” Linux tool called logger. As with managing any system, you want to accurately annotate historical events and adding entries into the system log file is a great way to accomplish this. You can view the system log file with this command: awalding@aw-vb:~$ cat /var/log/syslog
Leveraging the Linux Logger Read More »
Too many people shrug off Linux for fears of security with a free and open source operating system, even today. For those of us who know that Linux is no less or more secure than any other operating system, we must be sensitive to this and we must be well versed in Linux commands that
Linux Security Focused Commands We All Need to Use Read More »
Hello my Networking and IPv6 researchers and enthusiasts. I just started a PCAP repository at Github for IPv6 Extension Header (EH) packet capture examples. Honestly I found nothing worthwhile on the web, that’s not to say they don’t exists in some niche place, but I wanted something easy to access and easy to add content
IPv6 Extension Header PCAP Repository Read More »
I am often asked this question of where to access PCAP or PCAP-NG files so that folks can explore packet captures using Wireshark. I have always provided these resources in my Wireshark classes at the Online School, but thought I should also just list them here for public consumption. Look up the hashtag “captureeveryday” in
Where can I get PCAP Packet Captures for Learning and Exploration? Read More »
This blog article is a culmination of my years of experience in the networking and computing worlds. Over those years, where I began as a bench and field technician, I have had a number of classes that my employers sent me to to teach troubleshooting skills. Usually termed with the words “logical troubleshooting” or something
A Dive Into Network Troubleshooting Read More »
An essential function when administering a Linux system is viewing, configuring and managing users and groups. I cover adding users in this article: https://www.cellstream.com/reference-reading/tipsandtricks/582-using-the-useradd-command-to-create-user-accounts-in-linux That said, viewing users is done using a few simple commands. How To View Users on a Linux System Every user on a Linux system, whether created as an account for
Viewing Users/System Users on Linux Read More »
Like most operating systems, Linux can have multiple user accounts. The system administrator or root account, or users with sudo privileges are responsible for managing these users, as well as managing those accounts. Linux is a multi-user system, which means that more than one person can interact with the same system at the same time.
Using the useradd Command to Create User Accounts in Linux Read More »
I have been teaching Hands On IPv6 courses since 2011 – OMG thats 10 years plus!!! Over the course of time, the Internet Engineering Task Force and various companies have been expanding and detailing IPv6 implementation and specification. As our students know, we are very diligent updating our courses thanks to our Online School and
A Better and Complete IPv6 Bibliography Read More »
OK – so this article is for entertainment of all us network nerds. As many already know, pretty much every year, the Internet Engineering Task Force (IETF) releases humorous RFC’s – jokes. Usually these happen on or about April 1st to commemorate April Fools Day. Without doubt, some of these are classic and hilarious.
Humorous and April Fools Day RFC’s Read More »
Got to thinking the other day. What are the world’s most important RFC’s (Request for Comment specifications)? I decided to make a list. While the following are not in any order, I tried to base them (mostly) on date. While TCP came first, I still put the Internet Protocol on the top of the list.
The World’s (Generally) Most Important RFC’s of the Internet Read More »
