The ramblings of a computer geek
I recently came across an odd problem with the links from our Extreme Networks X695 switches to some Dell S5148F-ON switches, the X695 was running: 30.7.2.1, the Dell switch 10.4.3.6C1. Essentially what started the oddity was a transceiver failure. The equipment has been in production for a few months, all was working well. Suddenly a … Read more
NMAP (Network Mapper) is a great tool for scanning a network for hosts and devices. I’m going to write a more in-depth article soon, but for now here is a good command that can be used to scan your network (with a ping scan). By default Nmap will perform a reverse DNS lookup on the … Read more
Microsoft Active Directory uses the concepts of “domains”, a domain is the outer edge of a security compartment; within a domain, user accounts, computer accounts and resources are authenticated and share a common authentication source. There is also the concept of a “forest”, a forest is a collection of domains, in the most basic configuration … Read more
Had a little bit of trouble with this Micro-HDMI to VGA Adapter when trying to use it with Kali Linux, the Raspberry Pi would appear to boot up, but no picture was displayed. The solution was pretty straightforward, from another machine I opened the config.txt file and uncommented the following lines: The saved the file … Read more
Very occasionally a QSFP+ port might not be the correct form factor, what if you have a switch with only QSFP+ ports e.g. an Extreme Networks X770 but you need to connect up a device with an SFP+ port. Well, although you’ll be wasting a QSFP+ port this may help you. Extreme Networks provide what … Read more
The QSFP+ or QSFP28 ports of the Extreme Networks switches can be partitioned, what this means is you can make a 40Gbit QSFP+ port appear as 4 x 10Gbit SFP+ ports, however you’re require a suitable QSFP+ module for example with MTP port and a fan-out cable to split that MTP into 4 x LC … Read more
The OSI Model (Open Systems Interconnection) model is a set of rules and requirements to model and conceptualise the communication between two (network) systems. Yes, its theory, but in computing and networking it can be useful to use as a basic guide when troubleshooting. It helps you to rule-in or rule-out where a problem might … Read more
Notepad++ can be quite a handy tool to use, I often use it when building up bulk CLI commands to enter into switches or firewalls. Say you had a list of hosts and wanted to add some text to the beginning, that’s fairly easy, you just click, hold ALT and then select all the lines, … Read more
A fairly simple approach to providing uplink resilience. There are methods like EAPS or MLAG to give you uplink resilience, but sometimes you just need something simple. A redundant physical (or “Redundant Phy”) is essentially two uplinks to upstream switches and to avoid a loop, the downstream switch (i.e. the one with the redundant phy … Read more
If you wish to share a password with a user there’s various ways you can achieve it. But not all of them are secure! Let’s say you have the scenario that you are onboarding a user or you’ve had to reset their password for some reason. If that person is on-site, that’s pretty easy, you … Read more