Blog about the Internet, Pakistan and lots more

Saturday 29th September 2007

Suspension from hosting service

General

My blog was down for the last few days and the reason was pretty silly. Apparently, somebody had misused one of the web services running on my site to try to send spam and the hosting service simply suspended my account without even telling me.

It took a long online discussion with their support and a phone call to resolve the issue and bring the server back online. Any of the services that could be abused have been removed/reconfigured and this kind of thing shouldn't happen again.

It also taught me a few lessons about redundancy. Firstly, I shouldn't have been relying on a single server be the main DNS and control center for all of my domains.

Secondly, any test sites or services that could be abused should have been elsewhere and all data should have been mirrored for minimum outage at such times. Needless to say, this is something I'm doing from now on.

 

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Posted at 22:02pm PKT  Comments(1) |

Tuesday 25th September 2007

Scrybe - Another Internet success story

Pakistan Internet

Who says we Pakistanis don't have what it takes to play at the global level? There seem to be more and more success stories of technology startups that have their roots in this unlikely place. One of these, Scrybe, was recently mentioned on Islamabad Metblogs and I seem to recall a friend talk highly of them.

The Scrybe Blog is quite interesting too. Good luck to you all and hope you make it big.

 

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Posted at 15:23pm PKT  Comments(108) |

Tuesday 18th September 2007

Orgoo consolidated email and instant messaging

Web Internet

It has been about a month since I started my new job, yet haven't posted much about it. Since today is the first public demo of the service we are working on, it would be the right time to write something on it.

Orgoo logo

Orgoo is your one-stop communication gateway that allows you to use email and instant messaging from a single web-based interface. It also enhances these two widely-used applications with video and voice and integrates all of this into one, user-friendly interface.

Orgoo service

I'm involved in designing the backend of the service and making sure it scales well, though pretty much every aspect of the project is really fascinating. This is one of the most interesting things I have done for quite a while and reminds me of the early days of Vanguard.

Though the service is not yet open to the public, I have been using it exclusively for the past month or so. Despite being a long-term user and fan of Gaim, I'm now quite content with sticking to Orgoo for all of my instant messaging which includes signing on to MSN, Yahoo, Google Talk and now Orgoo Buddies. Video conferencing should also prove to be very useful once it sees more widespread use.

Orgoo has had mentions in a number of blogs and articles. Jehanara's blog, In the Line of Wire just posted about Orgoo yesterday. Here is an article by Michael Arrington about Orgoo and it has even received a mention in the Wall Street Journal.

So when can you try it out for yourself? Orgoo is being featured in this year's Tech Crunch 20 40 conference where we have a demo (in just over 3 hours from now). Once that is done, we'll open up the service for beta testing though judging by the huge amount of interest, this beta launch will be no less challenging than running a live service.

Check out the service and wish us luck with it.

 

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Posted at 17:58pm PKT  Comments(109) |

Friday 14th September 2007

Pakistan world leader in CNG cars

Pakistan Cars

Tee Emm recently introduced us to KamranZaidi.com and this article was of particular interest to me. I knew that Pakistan had the third biggest fleet of CNG (Compressed Natural Gas) powered cars in the world (behind Brazil and Argentina). Now I know that it has the highest.

The statistics must have been collected very recently since this page of the International Association of Natural Gas Vehicles still lists Pakistan as number 2. But with few people willing to pay for Petrol and everyone wanting their very own car, this growth shouldn't be surprising. Let's hope we can also be some of the most active adopters of other energy sources like wind and the sun.

 

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Posted at 10:19am PKT  Comments(100) |

Friday 7th September 2007

Connection closed by remote host

Linux Hardware

ssh_exchange_identification: Connection closed by remote host. This is the message I kept getting when I attempted to login to my web server a few days ago. Maybe you noticed the outage too. At first, a number of thoughts crossed my mind. Maybe the server is under such heavy loads that it's stopped accepting any new network connections. Maybe it's been hacked. Maybe it just wants a cookie. Googling for the error message also brought up similar suggestions.

Not having any other option, I asked for the server to be rebooted. It came back up within minutes, but still remained inaccessible to me and it took another reboot before I could login to see what was wrong. The hard disk had suddenly started showing signs of imminent death and some of the data had already been lost. dmesg showed a number of bus error messages and I knew I had to act fast.

A brief exchange of messages with the Cari.net support guys and soon, the server was up with a new hard disk and the previous one connected as a secondary drive. I copied over all the configuration and whatever data I could and presto. Everything was back to normal. It's a good thing I keep regular backups which allowed me to restore whatever was lost.

So now you know a couple of things. Namely that if you get the above error message, it could mean your system is in grave danger. Cari.net is an excellent host (thanks a lot guys. Hope you don't charge me for the hard drive). And lastly and most importantly, always keep backups.

 

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Posted at 20:40pm PKT  Comments(108) |

Thursday 6th September 2007

Region based load distribution

Technology Internet

Some time back, I blogged about using BIND's DNS Views to distribute traffic and then dabbled with multiple DNS "A" records to do round-robin load balancing for my websites. It seemed to work ok, but I wanted greater control and scalability. Also, a round-robin setup would have opened up another can of worms for any truly dynamic sites that required load balancing.

So the next step was setting up something much more sophisticated. There were 2 web servers to play with, one on the east coast of the US and the other on the west coast, and quite a few hurdles, such as BGP and the basic structure of the Internet.

The theory was that I'll split the Internet's IP space into 2 groups (using /8 network addresses), depending on which had better connectivity to my servers. Naturally, the network response time for each server would vary for most people and I could distribute traffic between the two while reducing latency at the same time. I believe that a number of very large sites such as Google and Hotmail are using this method (in addition to methods out of my reach, such as anycasting) to direct users to the closest server.

World network map

Deciding which /8 to put in which group was a difficult task since any given network address of this sort could be further divided among network operators in different parts of the world. However, since the primary goal was to divide traffic, network response time wasn't really a priority. I grabbed a list of IP addresses that were accessing my websites and attempted to ping and trace them from both of the servers.

After some consolidation of the results, I had 2 small lists of /8s, each supposedly closer (in network terms) to the corresponding server. The rest of the IP space, I split up with the help of this IANA address space document and the above map of the Internet's main registries (searched hard, but couldn't find a more useful one). This may not be the best approach, but it's better than randomly grouping a bunch of numbers.

Once the lists were compiled, the rest was just a matter of setting up these two ACLs in named.conf (trimmed) and creating views for each of them.

The ACLs:

acl eastcoast { 12.0.0.0/8; 59.0.0.0/8; 68.0.0.0/8;
	.......
	213.0.0.0/8; 217.0.0.0/8;
};

acl westcoast { 24.0.0.0/8; 38.0.0.0/8; 60.0.0.0/8; 63.0.0.0/8;
	......
	218.0.0.0/8; 219.0.0.0/8; 220.0.0.0/8; 221.0.0.0/8; 222.0.0.0/8;
};

The View statements:

view "eastcoast" {
        match-clients { eastslaves; eastcoast; };
        include "/etc/bind/named.root.hints";
        include "/etc/bind/named.eastcoast.zones";
};

view "westcoast" {
        match-clients { westslaves; westcoast; };
        include "/etc/bind/named.root.hints";
        include "/etc/bind/named.westcoast.zones";
};

The result? Average load on the two servers has dropped quite a lot due to the distribution and things appear to be working as expected. I'd love to implement this on a bigger network of servers with mirrors across the globe. That would really be something.

 

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Posted at 21:35pm PKT  Comments(49) |

Tuesday 4th September 2007

World power systems and watt kva conversion

Technology

These links should come in handy if you're travelling or working on a project that involves calculations of voltage, amperes, watts and kVAs etc.:

The last one is really just a revision of what you were taught in school, but the first has some nifty stuff about the types of power connectors, voltages and frequencies used in different countries. They were both quite useful when deciding which generator and UPSs we required for the new office.

 

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Posted at 20:38pm PKT  Comments(275) |

Monday 3rd September 2007

Return to blogging

Blogging

After a hiatus of about three weeks, I'm finally settling down with the new job and really want to get back to blogging. I didn't know so many people were regular readers and I've been asked a number of times about when I'll blog again. Well, here I am. However, the current work is so interesting and exciting that I won't be writing very frequently.

There's lots of material. Lots of interesting material, but you probably won't see much of it till I get time to setup a PC/laptop of my own and convert the material into blog fodder. Until then, I'll post whatever I can. See y'all soon and thanks for the support.

 

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Posted at 22:29pm PKT  Comments(5) |

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