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M-Shwari
WorkMore projects that I have been working on designing and developing have made the news! This time, it's a product that allows people to request loans via their mobile phones. Considering that large numbers of unbanked people in Kenya and the ease of access to mobile phones, this should really help those who need helping the most. Details here.

ShALLaX on December 13 2012 19:45:36 · Print
News-making Work
WorkI recently discovered that my work performed for M-PESA as an IBMer has made headline news in Kenya and has hit many websites, including the Financial Times. The project, for which I elicited requirements and then designed, architected, developed, and deployed the solution is used to allow people from all over the world to send money to users of M-PESA in Kenya. Details can be read here.

ShALLaX on November 01 2012 17:13:08 · Print
Further PPPoE/MTU Issues
PersonalHaving thought I'd cracked the MTU/MSS issues in my previous post, it turns out that I've been missing a lot of emails. I've now implemented the following IPTABLES rule and I have received an influx of emails from sites from which I haven't received emails in a good number of months:

iptables -I FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu

This clamps the maximum segment size to the MTU of the connection. Perhaps the cause of the previous command not working properly was invalid values. However, I'm not particularly interested in modifying the old command when this one seems to work perfectly.

ShALLaX on August 29 2011 11:41:37 · Print
The joys of PPPoE, MTUs and Blackhole Routers
PersonalI finally got around to setting my broadband up in my new house. I've come from having cable internet to now being forced to have ADSL as Virgin Media will not supply services to my street.

I was able to lift-and-shift my homebrew Linux router into my new setup with minimal changes required (I just had to add a PPPoE "dialler" and change the interfaces being referenced in the script). However, one thing had me stuck for a good few hours: some webpages simply didn't load through clients behind the router (though all websites loaded fine directly on the router itself).

I spent a lot of time playing around with my network configuration to see if any of my hardware was causing the issue. I removed my wireless bridge and connected directly to the router to no avail. I tried different computers, no luck.

Eventually, I broke out Wireshark and saw that a lot of my TCP packets were reported as being lost (missing segments). This triggered a memory of something I had read about blackhole routers (routers which will refuse to fragment a packet but instead of reporting back to the originator, they will silently discard the packet causing the connection to hang and then maybe timeout).

Ethernet (and cable) uses an MTU of 1500 while PPPoE has an MTU of 1492. All of my client machines were set to an MTU of 1500. After changing the MTU to match that of the PPPoE link, everything started working. Not a great solution, as I don't want to have to manually set the MTU on each of my clients. I did some research and found that DHCP can specify the MTU that all clients should use. However, it was clear that this wasn't a viable solution upon witnessing Apple equipment completely ignore the advice provided by the DHCP daemon.

Finally, I came across an IPTables rule that forces the MSS (maximum segment size) to a particular value for a given link: `iptables -t nat -A POSTROUTING -o ${EXTIF} -p tcp --tcp-flags SYN,RST SYN -m tcpmss --mss 1453: -j TCPMSS --set-mss 1452'

This must be added before the masquerade line (`iptables t nat -A POSTROUTING -s 192.168.0.0/16 -o ${EXTIF} -j MASQUERADE'). Implementing this goes against everything that has been put in place on the internet to prevent this problem (MTU path discovery should allow participants in a conversation to determine the maximum segment size dynamically). However, while there are still blackhole routers in the world, hacky work-arounds like this will be required. For now, I'm just glad that my internet connection is working properly. DNS updates are pending, but I can see them propagating throughout the internet as I write this!

ShALLaX on February 05 2011 20:02:02 · Print
Completion and Payment
PersonalContinuing my trend of making things difficult for myself, I've now completed the purchase of my house whilst out in Kenya on business!

ShALLaX on December 09 2010 13:51:44 · Print
Exchanged!
PersonalFinally, after nearly two months of looking for a house, phone calls, emails, letters, long drives, I've exchanged contracts for my house as of today! To make things even more stressful, I'm in India on business whilst doing all of this house-buying coordination!

ShALLaX on September 27 2010 12:29:33 · Print
Everything Signed
PersonalI received the mortgage offer 4 days ago and the signature documents (contracts, mortgage deed, etc...) 2 days ago. I spent some time over the weekend doing final checks over the documents and signed and returned them this morning.

Hopefully, that's most of the work out of the way now.

ShALLaX on September 13 2010 17:40:47 · Print
Legalese
PersonalToday, I received the legal documentation for the property that I'm purchasing. I envisaged there being a fair amount of paperwork, but the thick envelope waiting for me was larger than expected. Upon opening it, I also found that most pages are double sided and there's even an enclosed CD containing yet more legal documentation.

Looks like I have a fun weekend ahead of me deciphering the legalese contained within these documents...

ShALLaX on September 02 2010 21:10:47 · Print
Valuation
PersonalI had a phone call this morning from E.Surv informing me that they had been instructed by Santander (the lender that I've decided to go with) to do the valuation on my chosen property... except they didn't know where it is! After I gave them the details, they said they'd head down there tomorrow to do the valuation. Things are moving a bit faster than I was initially led to believe, but that's a good thing!

ShALLaX on August 18 2010 13:22:20 · Print
Tying up the Loose Ends
Today was spent driving to my solicitor to prove my identity and to instruct them to proceed with all of the legal work required when purchasing the coach house. This was about 1.5 hours of driving each way with only about 25 minutes of contact with the solicitor. I got some questions answered, which was very helpful. Fortunately, I won't have to make this trip again as everything else can be handled remotely. I also had to put down a chunk of money to go towards the costs involved in searches.

When I got home, I found that my 250 GBP cheque had been returned from the other coach house that I had cancelled my reservation for. Also, my mortgage application paperwork had arrived. I filled out the form and attached the required paperwork (again, proof of ID) then went off to the post office to post it. On the way back, I deposited the cheque.

My solicitor estimates that the contracts should arrive within the next couple of days and will send me all of the details as soon as possible.

There's nothing left for me to do right now!

ShALLaX on August 17 2010 14:40:34 · Print
Solicitor
PersonalFinding a solicitor wasn't such a problem. The housing developer recommended two firms, stating that they both have good knowledge of the contracts that they use and the development itself.

I gave a phone call to both firms and one of them didn't bother to get back to me, so that made the decision even easier. Both offered the same service at a similar price, however, the one that did respond seemed a bit more professional (certainly from its website).

I have an initial meeting scheduled with the firm tomorrow to prove my identity and hand over signed paperwork. Along with this, I'll need to drop off a lump of money up-front for the fees involved with the work that they perform.

In other news - my mortgage is definitely agreed in principle. I just need to sign the paperwork and provide any documentation (proof of ID, earnings, savings...) that may be required.

ShALLaX on August 16 2010 11:15:36 · Print
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