The ramblings of a computer geek
To explore how DKIM validation works first got an email in .eml format as an example email which was a known good email where the DKIM validation is OK. Meaning that both the header and the body are unchanged from when the email was first DKIM signed. There is a little tool called “dkimpy”, which […]
More...Just like the testing of SMTP using Telnet, you can also perform the same steps if the target server is using TLS, however because telnet won’t do the job here, you can use OpenSSL instead. Here’s a simple example:
More...Although I’ve covered this before if you want to add some headers into a test email, this can be done by just adding the required header into the “DATA” section. In the example below I’m adding in a header called “List-Id”. You would telnet into your mail server then type in the following:
More...When performing a VMware vCenter Upgrade for example from version 7 to version 8, you use the upgrade tool, this essentially works in two stages. Stage 1 deploy a new vCenter appliance on a temporary IP address, then Stage 2 copy all the configuration and data from the old vCenter appliance and then take over […]
More...At the time of writing (29/03/2024) the recommended EXOS (SwitchEngine) version for the X450-g2, X460-g2 and 5420 (as well as other hardware) is EXOS 31.7.2.28-patch1-75. We recently purchased some new 5420 switches and are upgrading some existing X450-g2 and X460-g2 to the latest recommended software versions. However we have identified an issue that currently at […]
More...A trial licence is fine for testing some stuff, but if you need to remove it, for example when it causes you issues in a stack when the master thinks it on perimeter, but the backup is not. Remove Licence (Option 1) https://extreme-networks.my.site.com/ExtrArticleDetail?n=000001267 Remove Licence (Option 2) https://extreme-networks.my.site.com/ExtrArticleDetail?an=000092952 Verify Current Licence Removing Stacking Licence Level
More...You may need to limit bandwidth, perhaps for a customer, or for an area of your network to avoid issues that occur when they saturate links, knowingly or unknowingly. In this example we’ll create a 20MBit Limit with a 250Kb burst, and we’ll make the switch drop anything that exceeds that limit. So in effect […]
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I was working on an issue whereby we were looking at traffic flow problem to a Dell Powerscale, attempting to identify why a particular VLAN was not able to be communicated with, we were unsure if the issue was network or storage. Luckily the Dell Powerscale includes “tcpdump”, so in this case we setup a […]
More...Attempting to purchase an in-app purchase (to buy coins) in Minecraft on an Amazon Fire Tablet I was constantly being told that my Amazon password was incorrect. The issue turned out to be down to OTP being enabled on my Amazon account, using Google Authenticator. To resolve the issue, it involved entering the password, with […]
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Becoming professionally registered is a great way to develop your career, drive your continuing professional development (CPD), while demonstrating to society and employers your commitment to the discipline. But what are the differing standards (levels) of registration, and what are the differences…..really? In this short article I’ll briefly summerise what I think the main differences […]
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