Dariusz on Software Quality & Performance

07/08/2014

Automated RTP headers analysis

Filed under: en — Tags: , — dariusz.cieslak @

rtp1IPTV technology delivers video streams using fast, but not reliable protocols (UDP). Those connection-less protocols do not guarantee delivery nor retransmissions of missing packets. We have to accept low video quality for some networks or add another layer above basic protocol that allows to control completeness of delivery. For this purpose we use RTP (packet order, completeness) and RTCP (retransmission requests) protocols.

In this port I'm going to show how effectively use Linux command line tools to analyse client – server cooperation regarding retransmissions for complicated real-world example. Basic RTP metadata collected by tcpdump is used as an input.

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16/04/2014

Wavemon – monitor your WIFI connection quality

Filed under: en — Tags: — dariusz.cieslak @

The old truth that everyone who spends days on business trips: hotels generally sucks at local Internet delivery service. The least important service in hotel is pretty crucial if you depend on it to finish some work after business hours.

However, if you are on Linux/Ubuntu machine there's a nice tool that will allow you to evaluate WIFI signal quality. It's name is: wavemon. It's a console tool that shows current (and previous) signal strength.

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Having real-time measurement you can decide what area of the hotel have the best signal strength.

15/04/2014

"Keep It Simple, Stupid" by UK goverment

Filed under: en — Tags: — dariusz.cieslak @

I was searching for current UK VAT rates as my client operates on this marked and found the following official page that was a delight for my eyes:

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Compare that with all that bloat you expect from your government and you know why some countries are much better for business than others.

09/04/2014

Computers's helping hand

Filed under: en — Tags: — dariusz.cieslak @

grub

08/02/2014

Self-signed SSL certificate HOWTO

Filed under: en — Tags: , , — dariusz.cieslak @

logo_sslSSL is used for (1) encrypting HTTP traffic and for (2) authentication server against browser's database of trusted certificates. Generating SSL certificate properly is important if you want your customer to use https properly. It costs few bugs per year, but your customers won't have any warnings in browser before SSL session (purpose number 2).

However, for internal applications, self-signed certificate may be a sufficient solution (purpose 1 only). You will find below a minimal commands to generate local SSL certificate (accept default values when asked for data on stdin):

mkdir -p /etc/lighttpd/ssl/local
cd /etc/lighttpd/ssl/local
openssl genrsa -passout pass:1234 -des3 -out server.key 1024
openssl req -passin pass:1234 -new -key server.key -out server.csr
cp server.key server.key.org
openssl rsa -passin pass:1234 -in server.key.org -out server.key
openssl x509 -req -in server.csr -signkey server.key -out server.crt
cat server.key server.crt > server.pem

Then lighttpd installation:

$SERVER["socket"] == "<YOUR_IP_ADDRESS>:443" {
ssl.engine = "enable"
ssl.pemfile = "/etc/lighttpd/ssl/local/server.pem"
ssl.ca-file = "/etc/lighttpd/ssl/local/server.crt"
}

Then you have to accept server certificate in your browser and voila!

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