Useful I.T. & VoIP Ramblings
Just a quick one, I think I have just worked out why I have a fascination with the Raspberry Pi.
When studying GCSE IT at school, the first chance for me to use a computer at school, the first programming centric software used was Winlogo. A simple drawing application that used code to manipulate a turtle (yes, I kid you not) to create vector shapes on a screen. Basically an overly complicated version of paint.
Continue reading “Modern vs. Nostalgia, Maybe Why I Like The Raspberry Pi”
From the last post, the idea of having UPS in my home may put me off forever, but to put it into context the unit had been installed before I was employed over 12 years ago, and over the past 2 years it was beeping intermittently to indicate a fault that a convenient press on any button would silence.
The post before that however had more gravitas, with my server being offline for close to a month all due to a one second power cut made me feel vulnerable to another downtime incident over something I couldn’t control. It was time to look into a Uninterruptable Power Supply to protect my server from power cuts that could knock my RAID out of sync.
A bit off topic but I should document what happened in work today. Got called to investigate a burning smell in one of the offices that house all the servers and network head end. The request was placid enough not to cause alarm but when I got to the room the smell hit you as soon as the door opened. Narrowing the smell down, it was coming from a caged off area underneath a desk that held the servers: An ancient IBM RS600 with UPS and two HP Proliant ML350 G5 with a shared UPS in two modules, along with what seemed decades of dust, discarded cables and old computer hardware that had accumulated over the years.
Once I got down there and started to fathom out what cables were in use and what could be safely isolated without stopping operations, the small wafts of smoke could be seen drifting up from under the desk. At this point it was obvious that any timescales for diagnosing the issue was getting smaller along with the grace period before the smoke detectors trigger the fire alarms and clears the store.
On the initial look, I noticed that one of the Proliant servers had a flashing LED next to a power symbol, two and two went together and thought that a power supply had failed spectacularly, so chose to switch it off, knowing the server was just for redundancy.
A minute passed and no let up of the smoke, by this time a CO2 extinguisher, pin pulled, was close at hand. Out of ideas I pulled all plugs from the wall, the RS6000 UPS failed immediately, the Proliants carried on under battery juice with 105mins left according to their UPS display (1 was still powered off). I left it another minute to rule out a problem with an input to the UPS, and with nervous relief the smoke subsided, a few back office systems went down with the RS6000 but the customer end Proliant stayed online.
With the batteries keeping customer facing systems online for a further hour or so, it was a safe time to find the culprit. An extensive sniff test and the UPS for the RS6000 was pointed out as the source of the incident, possibly why it failed as soon as power was cut. It was taken out of commission and bypassed to get the IBM machine back online.
A rather eventful day compared to the normal, mundane non-IT job. I haven’t opened up the failed UPS to see what went wrong, nor would I want to thinking about what state the (probably) lead cells are in.
It had to happen, after years of reliability (apart from an ISP related failure), I had my first hardware related downtime, caused by a power cut that lasted all of one second.
In the electric free event, only a few electricals switched off, my HP Microserver was one that lost power and restarted. Looking at the headless unit after boot, all lights were on, HDD light on full and the network lamp was flickering away as normal. However trying to access the server, even down to a simple ping, it was unresponsive.
Time for investigation, and it was ripped out of its kitchen cupboard home and connected to a TV along with a keyboard and mouse. From there it was painfully apparent that the RAID mirror had been corrupted and the BIOS couldn’t find the OS. The OS drive was in a RAID 1 mirror so I took out the primary master disk (first on the BIOS boot priority) and tried to boot the remaining mirror. This time it started Windows. All was back on track it seemed, waited for the other mirror holding data to re-sync then changed the boot priority in Windows (not BIOS) to use the good OS drive first. A restart to plug the un-synced HDD in and it booted fine, no SMART errors reported with the removed drive and it started to rebuild the system mirror.
Things then took an ugly turn, using the desktop would be as normal for around 90 seconds, then the system would freeze, apart from the mouse for minutes at a time, before coming back to life and displayed applications requested before the freeze. It seemed as if the system was having big problems trying to read from the disk, it would run fine simply moving the mouse around, but when selecting a program it would freeze, and depending on what you requested to load it could be up to 20 minutes. While in this state of freeze, the HDD lamp on the Microserver would be solid, so naturally it pointed to either a bad hard drive or the RAID mirror was having problems.
Not finding a solution, I admitted defeat and did a fresh install of windows, but still wanted to get the latest backup, the data mirror was easy to recover by just removing the drives as they can be imported on a new install. The OS drive was a bit trickier, the system would freeze if I tried to copy files as is. Luckily I had the old 250GB drive that came with the Microserver, it had Windows 2003 on it and ran on the system until more capacity was required, it was swapped out for a 1TB drive. Not so lucky was that the only software found to copy files from a Foreign RAID mirror cost £50, I shelled out this money as my data was more valuable than the asking fee. Along with an extra 1TB drive to hold the data while I juggle drives it ended up costing me a few quid.
All this from a 1 second power cut.
RAID 1 on a system disk:
Research says this is not a good idea. While it will run with no issues during normal operation, after an unexpected shutdown a RAID controller just can’t tell the difference between a good file and an un-synced, corrupt file, so the controller will either guess, which could restore an out of data file, or create a mismatch of current and out of date files that ultimately brings your OS to a halt.
It’s simple, instead of the process of installing PHP, MySQL, assigning permissions and all the debugging that many of us have gone through, Microsoft has come up with WPI, or Web Platform Installer.
Amongst other web applications, WordPress is the most popular and it makes the install on Windows as simple as a few clicks.
So far I’ve tried it on Server 2003 R2 and Server 2012 R2, both with instant success.
It’s available at: http://www.microsoft.com/web/downloads/platform.aspx
My first RPi was intended to serve as a learning tool for Linux, allowing me to tinker with with a machine without the risk of causing damage to a computer I need on a daily basis, much akin to the design philosiphy on the Raspberry Pi. VM was available, but the ability to program straight to a physical machine akin to the microcomputer revolution of the 80’s that the Pi foundation is trying to rekindle interested me, as I was not around for that part of history.
However in my search for a project that interested me, I found Raspbmc (Now OSMC), the media centre centric OS was such a perfect solution for my televisual needs that my first RPi became dedicated to it by complimenting my home server to stream files to my screen.
With the recent release of the Raspberry Pi B+, it was time to have another go at figuring out Linux from the command line. At £35 delivered it was still cheap, and this time I know better to source the accessories like micro SD card and Power Supply in advance for a lower price.
Let learning commence!
Recently I had an attack on this website, as I run a WordPress site this is not an isolated incident. However, in this instance it was a rather aggressive attack compared to the bandwidth I have available. The attacker in this case was saturating my connection with POST commands to wp-login.php as apposed to the usual attacker who send requests every few seconds, in an attempt I presume to not be noticed.
Knowing that this was a sustained attack I first turned to enabling Windows authentication to wp-login.php, this made things worse as the data sent from a HTTP 401 error to this page used more data than WordPress denying access.
Failing this, I blocked the IP address from IIS so it will return a 403 error, this brought the data sent back down to normal but still the attack continued.
As a last resort, I performed a lookup on the attacking IP via the WHOIS database, and discovered the attacking computer was on a hosted server in Malaysia:
% [whois.apnic.net] % Whois data copyright terms http://www.apnic.net/db/dbcopyright.html % Information related to '183.81.162.0 - 183.81.162.255' inetnum: 183.81.162.0 - 183.81.162.255 netname: IPSERVERONE-MY descr: IPSERVERONE - Co-location - AIMS Data Center country: MY address: L7-13, Level 7, Brem Mall, address: Jalan Kepong, 52000, address: Kuala Lumpur e-mail: abuse@ipserverone.com abuse-mailbox: abuse@ipserverone.com phone: +60-3-625-95-625 fax-no: +60-3-625-95-629 e-mail: ipnoc@ipserverone.com % This query was served by the APNIC Whois Service version 1.69.1-APNICv1r0 (WHOIS4)
The website dawhois.com was the first best match and reveled that the hosting service for this site was ipserverone.com, and in desperation to solve this I contacted the abuse email listed above.
I have often contact ISPs in this method when receiving an attack, but none have come to fruition, not even a response, this time I got an answer:
Hi James,
We are sorry to hear that, could you please verify now, is still got attack to your site?
Checking that the attack is still going on, I replied that is is still happening:
Hi James,
Seems that I’ve disabled an access few sites that contain suspicious codes.
Is the issue persist?
Checking again, it stopped! Guessing from the fact that the attack continued after changing responses from my server to 401 and 403, it was a bot running, but many thanks to Mohd and the people at ipserverone for stopping this attack and giving me back my bandwidth!
Since I run this blog from from my home web server, I have quick access to the web logs to see how my site is doing, I check this on an infrequent basis but always revisit them to see who/what is looking at my site.
My normal routine is to simply look at the log folder to see the file size of the daily logs, I’m used to seeing spikes in my traffic, caused by bots trying to guess my WordPress admin password, however on 20th December the file size was abnormally high, a look at the log shows a barrage of requests for only one image file:
A look at the referring page in the logs pointed to a forum for people looking for freebies, and a popular forum at that! A forum user trying to get their point across about what Sky Router they had Google searched it, found my image and linked it on the forum post.
I didn’t necessarily have a problem with this, since it was a “not for profit” point, but my beef was that the user decided to link the raw 4320 x 2880 image taken off my bridge camera, weighing in at 4.87MB!
On the forum a few grumbles over the image started to appear, all about it causing long page load times, No shit! At my current upload speed it takes 76 seconds to download, couple that with around 5 requests per min it would take much longer.
Lessons Learned:
FOOTNOTE:
The forum post that my image was linked to was about an offer to get a free Sky Wireless Booster. So I thought I may as well:
I originally purchased my iPad so I could peruse the net from the comfort of my sofa, and so far I’m impressed with what I can actually achieve on it. The limitations if iOS and the form factor over my trusty laptop are there, but I’m trying to blur the differences.
Apart from the almost impossible-to-use spreadsheets, I kept referring to the laptop when I needed to Remote Desktop into my server. Luckily there is an iOS solution for this in the guise of the Desktop RDP app.
I had the free version on my iPhone, but due to the small screen being productive was impossibly tedious, and so was left on my phone for server emergencies.
The iPad version however, is a lot more feasible, setting it to connect to my Win 2003 server with a screen resolution of 1024×768 means that the desktop can be controlled with all the desktop in view.
The paid version of Desktop RDP includes the full keyboard, and the ability to drag and right click, something of a necessity for windows, but the more clever users the get along in the free versions without these “perks”, although I wonder if it is not worth the £3.99 for these.
Looking for apps that allow you do what on a PC would be easy is a perilous journey, and in the case if trying to find a suitable office app, an expensive one. But I am glad, if not relieved that this purchase turned our to be a good one.
If I’m out on the wilderness armed only with an iPad and need the features of a PC, I can now just RDP into my server to get the best of both worlds, a lot better than lugging around my desktop replacement notebook.
Hello,
It has been a while since my last post on this blog, I have a few hints and tips to put on here but my obsession with perfection and formatting get in the way of posts making it here.
However I have just taken receipt of the new iPad … 4 …. Retina … I don’t know what it is officially classed as. But I soon discovered the WordPress app for iPad, that is compatible with blogs hosted on own servers.
Hopefully more posts will be on the way!
Until then, here is a quick snap to test it’s photo ability.