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Showing posts from 2014

Strange problem on KVM VPS

This one for the X-Files.

I have been helping a client migrate his web server from one VPS to another because he needed more disk space. His previous VPS is based on Xen, and the migration is to a KVM-based VPS.

Everything was smooth-going at first. I installed Debian 7 x64, all the usual packages: nginx, php, mariadb etc. Easy. Configured and tested the setup. Easy.

Then I migrated his database and web server over and asked him to do some business-side testing. That was when we hit an unusual snag. His PayPal IPN wouldn't work.

At first, I traced the logs, thinking it was some kind of PHP code incompatibility. Nothing. The code will break at this point:

$fp = fsockopen('ssl://www.paypal.com', 443, $eno, $estr, 30);

and never return.

I was stumped. So I wrote a simple test program that retrieves the HTTP and the HTTPS version of google.com. Lo and behold, the HTTPS fetch breaks right at that point with:

    Illegal instruction

I looked up what that means and found that it is…

Bluetooth headsets: Samsung HM1700 vs Plantonics M25

I had been using a Samsung HM1700 headset for over a year now. Recently, the Plantonics M25 was on sale. It looks a lot smaller, lighter and sleeker than the Samsung HM1700, it supports A2DP, it has long battery life, so I bought one to have a try.

The thing about Bluetooth headset is that you can never tell how well it works for you from the specs. You have to live with it for a week or two before you can tell if the two of you are compatible, sorta like a roommate or girlfriend. So I lived with the M25 for a week.

Samsung HM1700

Pros:
Long battery lifeGreat reception Cons:
Bigger and heavierEar loop is not as comfortablePlantonics M25

Pros:
Long battery lifeSleeker, smaller and lighter Ear loop is fitting and comfortable Cons:
Too many A2DP dropouts for my liking. By that, I mean the A2DP stream will drop out for a second or two being picking up again. This happens when I turn or bend my body, pick up a tool etc. It happens with the HM1700 too, but much less frequently. So it seems lik…

Bitcoin - Figures on transaction cost

Here are some figures on transaction costs in cross-border transactions.

Currently the de-facto reference currency in cross-border transactions is the USD.

A recent purchase of USD186 using the credit card resulted in the following line items in AUD:
AUD (from USD) - $202.00Currency conversion assessment fee: $0.40International transaction fee: $3.00 Cross border assessment fee: $1.60 Ignoring the spread used in the currency conversion, the transaction cost is about 2.5%. The actual transaction cost taking the spread into account is probably about 3+%

A recent purchase of USD700 using PayPal incurred a fee of $23 (buyer or seller pays). The transaction cost is a whooping 3.3%. I happened to have some USD in my account, so I didn't need to perform currency conversion. PayPal's spread in forex rate is notoriously poor compared to other avenues.

A purchase of 1.45BTC (approximately USD1085 at that time) incurred a transaction fee of 0.0002BTC, which is negligible. Speed rivals tha…

Bitcoin - Micropayment system for the Internet?

I have been dabbling with crypto-currencies, specifically Bitcoin and Litecoin, over the past 12 months. Everything from mining to e-commerce to currency exchange. I think I "get" the magic of the whole idea now.

For better or for worse, crypto-currencies drastically reduces the friction of money flow. You probably won't be able to find another means of moving money at a lower transaction cost, especially when small amounts are involved.

In addition, the speed of transfer is excellent for a distributed system. With Bitcoin, it takes a few minutes. With Litecoin, it takes a couple of seconds. The low transaction fee and fast transfer speed respect no geographical boundaries. It applies whether you are moving money within the same country, or between two countries on opposite ends of the Earth. Which probably freaked more than a few legislators out.

Plus this is a distributed system with no central authority to slow things down or screw things up. PayPal is fast, but try …