April 22 2015

How to find an internal/local Certificate Authority

Many times when I’m new to an organisation I’ll need to do a discovery within the environment to see what technology exists – including local Microsoft Windows Certificate Authorities. A very quick and easy way to do this is to use the certutil command with the follow syntax:

certutil -config - -ping

If there is a Certificate Authority published in Active Directory then you will get a popup box with a list of them. If not, you’ll see something like this:

certutil

certutil

The command is also useful for testing the responsiveness of a Certificate Authority – if you select an existing Certificate Authority from the popup box, certutil will ping it.

April 21 2015

Melbourne based System Center guru goes it alone!

I good friend of mine who I met many years ago in the workplace has decided to open up his own consultancy.  For anyone that does work in the System Center space, they would already know Tao  from his fantastic blog over at http://blog.tyang.org/.  Tao is  a technical genius who focuses on the Microsoft System Center stack however he truly lives and breathes SCOM (Operations Manager).  Good luck to Tao and I recommend you check out TY Consulting’s new website over at http://www.tyconsulting.com.au/

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April 20 2015

WordPress showing garbage characters on front page

After installing the W3 Total Cache plugin for WordPress, I noticed that my front page wasn’t rendering properly in some browsers including Internet Explorer (Chrome seemed fine).  For example:

More garbage than usual....

More garbage than usual….

There were many forum posts on this but none of the answered seems to help.  There is even a section in the plugin FAQ however this wasn’t the solution for me:

I see garbage characters instead of the normal web site, what’s going on here?

If a theme or it’s files use the call php_flush or function flush that will interfere with the plugins normal operation; making the plugin send cached files before essential operations have finished. The flush call is no longer necessary and should be removed.

For me, the issue was HTTP (gzip) compression.  I needed to disable this.  In the  W3 Total Cache plugin, under Browser Cache, I deselected the Enable HTTP (gzip) compression option and the website started working properly again.

 

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April 18 2015

Free ArchiMate tools and resources

archimate

There are many tools in the market for ArchiMate (the modelling language for enterprise architecture).  I’ve come across a handful of very good free resources that may be of use to others:

 

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April 17 2015

Checking worldwide DNS propagation

Recently when moving website hosts I needed to update the DNS A records to point to the new hosting provider. Global DNS replication can take time and there is a great free tool to perform a DNS lookup against multiple name servers located in different parts of the world.  For example, the image below shows that the Google DNS server in Mountain View CA (USA) has a different value to the rest of the DNS servers.

For blog.danovich.com.au

For blog.danovich.com.au

When I tried again an hour later, they were all the same meaning that global replication had finished.

See https://www.whatsmydns.net for the free web based tool.

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March 30 2015

Why I moved from Windows Azure to Amazon AWS….

After using Windows Azure to host my WordPress blog for around 6 months, I eventually lost patience with their product offering and support team and starting looking elsewhere.  I was receiving ongoing database connection issues and intermediate site outages.

Failing database connections…

The “This site is currently not available… please try again later” message became very common.  This is due to the way Azure manages it’s resource limitations – while other providers will simply throttle your site once you reach a certain level of CPU or RAM usage, Azure actually stops all connections to your website and takes it offline.   If you ran a large corporate website, you would enable to scaling options that will allow the instances to grow when there is increased demand however this comes at a financial costs and for me, I couldn’t justify it for a “hobby” blog.

Site unavailable.... again...

Site unavailable…. again…

After limiting my WordPress memory usage, I couldn’t understand how I was going over my memory allocation. I opened 2 support cases with Microsoft however after more than 20 emails back and forth, the engineer couldn’t explain what was happening and kept referring me to the pricing page for Azure.  Very frustrating, eg “ME: As I have stated 3 times now, I want to understand how the memory usage is calculated – when looking at the monitoring section for the last 7 days, the highest the MemoryWorkingSet gets to is 451.5MB. My WordPress instance is hard limited to 256MB and PHP limited to 128MB of memory. So why am I now constantly being charged for using over 1GB of memory?”.  So I gave up on Azure and went over to Amazon.

I figured I would try out their T1 Micro Instances that would cost be around $175 per year (after 12 months of being free). I certainly liked this section of their policy, it was something that Azure didn’t do:

When the Instance Uses Its Allotted Resources – We expect your application to consume only a certain amount of CPU resources in a period of time. If the application consumes more than your instance’s allotted CPU resources, we temporarily limit the instance so it operates at a low CPU level. If your instance continues to use all of its allotted resources, its performance will degrade. We will increase the time that we limit its CPU level, thus increasing the time before the instance is allowed to burst again.

I’m happy for the performance to be degraded, that doesn’t bother me since this is really just a personal blog. Through the AWS Marketplace, I order the WordPress powered by Bitnami, in the Australian data center on a t1.micro EC2 instance.

Wordpress powered by Bitnami

WordPress powered by Bitnami

After a couple of hours of configuring and migrating content, I’m now fully up and running on AWS.  So far so good.

 

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