Whispers & Screams
And Other Things

OSPF DR and BDR Election

Participating routers in an OSPF network have varying roles to play in ensuring that the processes which route the data around the network maintain a true and accurate picture of the network topology. The two primary roles in this structure are the Designated Router (DR) and the Backup Designated Router (BDR). Their roles, whilst primarily aimed at maintaining network function from a routing perspective, are equally focused on ensuring that network bandwidth used to accomplish this is used judiciously.

An Election


Consider a multi-access environment (such as LAN or MAN), where three or more routers are connected together. If all the routers in the OSPF network had to form adjacencies with every other OSPF router present, forming a fully meshed OSPF adjacency network, the resultant conceptualised routing mesh would be overly chatty flooding Link State Advertisements (LSAs) with each and every other OSPF router. As a direct result, router CPU load and network bandwidth would be consumed wastefully. OSPF is designed to be far more efficient in its use of these resources, and, in order to prevent this from happening, OSPF holds an election process to determine and fill roles named Designated Router (DR) and a Backup Designated Router (BDR) so that the workload of propagating routing information around the network is more effectively managed. Election for the DR and BDR is determined primarily on the Router Priority (which by default is 1) and the Router ID. If the value of the router interface priority is changed to 0, it prevents that router from becoming the DR or the BDR.

Router priority can be adjusted on Cisco routers on a per interface basis. The Router ID however is a 32-bit number that uniquely identifies the router in the Autonomous System. One algorithm for Router ID assignment is to choose the largest or smallest IP address assigned to the router. If a router's OSPF Router ID is changed, the router's OSPF software should be restarted before the new Router ID takes effect. Before restarting in order to change its Router ID, the router should flush its self-originated LSAs from the routing domain or they will persist for up to MaxAge minutes. Cisco uses a method that some other vendors choose to follow, but it is not a requirement. If you have a loopback interface, since that's the most stable interface on your router, that will be used. If there is no loopback interface, the highest IP address on the router is used. If there is more than one loopback then the highest of them is used. In many elections in OSPF, the higher RID wins. this is the logic for choosing higher over lower. It should be noted however that you can manually specify an RID that isn't even a valid ip address such as 224.1.1.1.

Drothers


The DR is the router which receives LSAs and other updates when there is a change in the inter-neighbor communications. These LSAs are sent out by the DROTHERS routers (all non-DR/BDR routers), and consequently, any further updates are propagated by the DR to the rest of the DROTHERS routers. The show ip ospf neighbor command, when executed, indicates the non-DR/BDR routers as DROTHERS. Every network segment in OSPF has a DR and a BDR.

The Process


What actually happens is that whenever there is a change in network routing status, instead of flooding each and every path with LSAs advertising new information about network topology, the update is only sent to the DR. The DR then takes on this job and floods the routers in its network segment with the update. If the DR fails or is not functioning, the BDR takes over. When this happens, the BDR replaces the existing DR as the new Designated Router, and a new BDR is elected.

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Skye The Husky

IMG_4387 IMG_4388 IMG_4389 IMG_4393

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The Latest Referrer Spam - Semalt and Buttons For Website

So, you manage some websites, you're a fan of Google analytics or even just use a local server log analyser to view your site stats. If this is you then you cant fail to have noticed that your sites have been getting visits lately from referrer bots called semalt.com and buttons-for-website.com. There are a couple of good reasons why you shouldn't ignore this traffic. In fact you should block it from your site and if you're using an Apache web server, which most people are these days, then I'll show you how to do it for yourself.

The Semalt and Buttons For Website bots dont seem to be harmful to websites per-se however their effect on SEO should not be ignored. If your website is getting 50 or 100 hits per month from these things it will affect your overall clocked bounce rate since these bots is always bounce. This will make it seem as though visitors to your site are not finding the material they were looking for and, to the search engines, may decrease the perceived quality of your site and thereby effect your ranking.

It should be noted that Semalt is not your typical bot. Analysis shows that the company uses a QtWebKit browser engine to avoid detection. Consequently, Semalt bots can execute JavaScript and hold cookies, thereby enabling them to avoid common bot filtering methods (e.g., asking a bot to parse JavaScript). Because of their ability to execute JavaScript, these bots also appears in Google Analytics reports as being “human” traffic.

Recently, substantial evidence revealed that Semalt isn’t running a regular crawler. Instead, to generate bot traffic, the company appears to be using a botnet that is spread around by a malware, hidden in a utility called Soundfrost.

“Botnets sometimes compromise computers whose security defenses have been breached and control conceded to a third party. Each such compromised device, known as a “bot”, is created when a computer is penetrated by software from amalware (malicious software) distribution. The controller of a botnet is able to direct the activities of these compromised computers” – Wikipedia

Their Botnet involves hundreds or thousands of computers and too many IP addresses to be able to effectively bloc the crawler via IP Exclusion in Analytics. To see a list of IP addresses associated with Semalt go to this page. It will return a long list of (at least hundreds) of IP addresses associated with Semalt.

Blocking these sites like you would other crawlers/spiders in your robots.txt file may not be effective either since compliance with directives in the robots.txt file is voluntary and those who are running something Black Hat certainly do not care about complying with the wishes of others.

Buttons For Website seems to be very similar in function (alleged to be a spambot/botnet) except that it uses a different delivery method. In this case the Buttons For Website site simply offers a handy sharing tool for you to install on your website. However, by installing the supplied code, you are potentially creating a way for a person to hijack (zombify) the web browser of visitors to your site.

According to one article I found javascript hijacking can also be used for nefarious purposes. Even though the article is about using javascript to create a botnet through online ads the same principle should work just as well with a permanent installation like sharing buttons.

“Adding arbitrary JavaScript to ads is easy to do and in the experience of the researchers wasn’t checked very closely by the ad network. To make it more convenient to change the malicious script, rather than placing the script itself in the ad, they put in the script source.” – NetworkWorld

Semalt And Buttons For Website Blocking


Since potentially both Semalt and Buttons For Website traffic is going to be coming from a large number of IP addresses (Semalt from infected computers and Buttons For Website from visitors to infected sites) the option of blocking this traffic by IP exclusion in Analytics would not be effective. An alternative, which is what I have used successfully on all of the WordPRess sites that I manage, is to block traffic from semalt.semalt.com and buttons-for-website.com in the .htacces file of each site.

To do this you have to have access to the files in the root directory on your web host that make up your WordPress, Joomla or Drupal site and be using an Apache system (most hosting providers do). If you have never worked with the files in the root directory of your site and/or are not familiar with editing the .htaccess file ask your webmaster to do it for you. If you make a mistake when editing your .htaccess file, the result can make the site completely unavailable.

If you are comfortable with editing your .htaccess file then adding the following code to it should block both Semalt and Buttons For Website traffic to your site.

# block visitors referred from semalt.com
RewriteEngine on
RewriteCond %{HTTP_REFERER} semalt\.com [NC]
RewriteRule .* – [F]
# End semalt block
# block referer spam buttons for website
RewriteEngine On
RewriteCond %{HTTP_REFERER} buttons\-for\-website\.com
RewriteRule ^.* - [F,L]
# End buttons for website block


At Rustyice Solutions we use this method to block Semalt and Buttons For Website traffic on many WordPress, Joomla and Drupal sites that we manage and so far it has resulted in the total elimination of all traffic from these two sites from all of the managed websites. If you do not have a webmaster and are seeing traffic from these sources to your WordPress website we will be happy to help you with the problem. Contact me using the contact form on this site (Click Here) and I will be happy to help for a very small fee.

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GIMP plugins that stand out from the crowd

You may well be wondering what GIMP is. GIMP stands for GNU Image Manipulation Program. Quite simply it is one of the most useful programs I have used throughout the last 10 years. Its an open source program that's ostensibly supposed to compete with Photoshop. When you compare the two programs they are surprisingly close competitors in all but one key area, price. Adobe Photoshop having moved to a subscription model comes in at about £50 per month give-or-take, GIMP on the other hand requires a one off payment of £0.00p. No brainer I'd say. On top of this, GIMP is the best open-source photo-editor out there in the marketplace. It packs in a neat set of features that can rival those of Photoshop. And that's not the end either! More than what GIMP lacks in terms of in-built features, it settles with its powerful set of plugins which are unbelievably small, and extremely versatile.

In my entire history of using GIMP, I haven't ever felt any need to consider using Photoshop. If there was something I just flat out could not do with GIMP that I'd be able to do with Photoshop then I might have considered it but I've never come across anything even close. In addition, there are a surprisingly large number of plugins for this elegant software, that can spice up your GIMP experience, especially if you're serious about your photos. I'll go on to list some of the most powerful and cool plugins for GIMP. All of them are free, and I'll provide the download links to each of them individually. Most of the effects below simply require you to download the respective files, grab the .scm script and put it inside your GIMP folder's 'Scripts' directory. Restart GIMP following each installation, and your effect is installed.

1. Photo Effects


This is really one big boss of photographic effects. It packs in a number of powerful, cool effects, neatly arranged in four categories:

Sunset at Maidan, glassified with the
Stained Glass effect.


A. Artist (Note Paper, Pastel, Water Paint, Stamp, Warp)
B. Style (Chrome Image, Cross Light)
C. Texture (Brick Wall, Patchwork, Stained Glass, Texturiser)
D. Others (High Pass)

Once installed, any of the above effects can be flawlessly applied to your photos, to make even ordinary shots look special. The merit of this plugin is that, it packs in so many cool effects into an unbelievably small sized package, 27 KB! Yeah, you read me right. ;)

Another glorious addition is the degree of end-user customizations. For example, while applying Stained Glass effect, you can choose the size of each glass-element in pixels! The Note Paper effect is something to be reckoned with. And to be honest, the textures are just way too superb.

Download: http://registry.gimp.org/node/97

2. HDR and HDR Plus plugins


These are two very powerful plugins that can add colour and life to otherwise bland shots. HDR or High Dynamic Ranging process attempts to capture and/or bring back the true colour (as it appears) to each element on the photo, thus livening it up.

Notice the original shot below:


Now, the colours obviously look a bit faded off, and it's time to apply the GIMP HDR Plus plugin. Look at the result below:


The result is clear, it's far more attractive and cool, even though the original shot did not have a good colour composition. I would say, the HDR plugin is the best if you use online Photo-sharing sites such as Flickr or Shuttershock.

Installation is very easy, just download and shift the .scm files to the scripts directory. These cool effects (HDR and HDR Plus) can be loaded from Scripts-Fu=>Enhance=>Fake HDR/Fake HDR Plus.

Download: http://registry.gimp.org/node/11776

3. National Geographic Script


This is a smooth and powerful run-once script, that can effective turn even ordinary shots into quality ones. Not that it does live upto its name, but it comes really close! As usual, nothing is better than a demonstration. Consider the photo below, shot at Duars, North Bengal (India).


Although the colour composition is okay, it still lacks some jibe, and just doesn't appear a very quality shot (it may vary, though). I took it with my Canvas 2 Android phablet, using the 8 MP shooter distilled to 5 MP. Now, let us apply the NatGeo script, and the result is shown below:


It's clear that the photo below is a far more refined and quality shot! This is the magic of the NatGeo script. It can be accessed from Filter=>Generic=>National Geographic.

Download: http://registry.gimp.org/node/9592

4. Quick Sketch


Quick Sketch is a very clear name, it digitally turns your ordinary shot into a fake painting, which is often just too marvelous to be considered a hand-drawn one though, let me warn you. However, it's very artistic, and will certainly help you amaze your friends and social contacts. Consider the photo of Jeses below:


Now, after adding the Quick Sketch effect:


Looks genuine enough! Not surprisingly, it also reduces the photo size in most cases, doing away with colours and extra graphics. It can be accessed from Scripts-Fu=>Artistic=>Quick Sketch. And it allows you to customize the blur factor too. And behold! It's only 3.25 KB!

Download: http://registry.gimp.org/node/5921

5. Blue Sky and Clouds


This is one neat little script that turns otherwise greyish or whitish sky blue, complete with fake clouds and blur. It just appears way too magical, doesn't it? Well, with the plugin, it's a breeze. Consider the photo below, an okay shot that however doesn't capture the serene bluishness of the sky:


Naturally, we'd use the plugin here. The result is shown below:


The plugin also allows tremendous customizations, and you will need a lot of time before mastering it. But even if you just accept the default settings, it'll look cool. And it's just around 5 KB in size. Access it fromScripts-Fu=>Darla=>Blue sky and clouds.

Download: http://registry.gimp.org/node/193

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Newmilns Tower

towerNewmilns and Greenholm is a small burgh in East Ayrshire, Scotland. It has a population of 3,057 people (2001 census) and lies on the A71, around seven miles east of Kilmarnock and twenty-five miles southwest of Glasgow. It is situated in a valley through which the River Irvine runs and, with the neighbouring towns of Darvel and Galston, forms an area known as the Upper Irvine Valley (locally referred to as The Valley). As the name suggests, the burgh exists in two parts - Newmilns to the north of the river and Greenholm to the south. The river also divides the parishes of Loudoun and Galston, which is why the burgh, although generally referred to as Newmilns, has retained both names.

Newmilns means "the new mills", from Old English niwe "new" and myln "mill", the name being recorded as Nawemeln in 1126 - the plural Newmilns is a recent addition.

At the end of the 16th century, refugees from France and Flanders settled in Newmilns, bringing with them skills and techniques in lace making. Most houses had a loom by the end of the 18th century. The introduction of the power loom in the late 19th century marked the beginning of the golden years for the lace industry in Newmilns. By the end of the Second World War, there were 12 lace and madras factories in Newmilns. The importance of lace is reflected in the architecture of public buildings in the town centre, such as Lady Flora's Institute and the Morton Hall.

The subsequent decline of lace making in the town, due to growing competition from overseas, led to a decline in the fortunes of Newmilns. Town centre buildings fell into disrepair and an aura of dereliction and depression led to historic properties becoming uninhabitable, roofless or being demolished. From 1999 to 2005 a Heritage Lottery Fund-supported project known as the Newmilns Townscape Heritage Initiative carried out extensive building restoration and renovation works, including the environmental improvement of open space and waste ground in Newmilns and reinstatement of architectural detail and features.

Newmilns Tower (which once had impressive gardens and orchards surrounding it), was erected in the centre of the town about 1525 by Sir Hugh Campbell, Earl of Loudoun. Newmilns Tower was built following the destruction of Loudoun Castle by the Kennedys of Culzean, during which Sir Hugh's wife and nine children were all killed. The attack was apparently in retaliation for the role Sir Hugh had played in the murder of a kinsman of the Kennedys. The Earls of Loudoun continued to reside at Newmilns Tower until 1615. It is sometimes suggested that the Earls of Loudon later built what is now the Loudoun Arms as a town house.

Newmilns Tower saw further use in the religious wars of the mid 1600s as a prison for Covenanters. Some of the prisoners held here were freed in a raid on the tower, but at least one was killed during the escape.

The tower was fully restored by the Strathclyde Building Preservation Trust in the 1990s and is now a privately owned residence.

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