George Georgovassilis writes about technology architecture
The 5G mobile network specification introduces network function virtualization [NFV] which enables mobile network operators (carriers henceforth) to expose network resources to business applications as PaaS solution building blocks [SBB]. Naturally, this moves 5G into the focus of software architecture. Unsurprisingly, the NFV specs detail services from the carrier's point of view, so they are … Continue reading Software architecture for 5G networks
In this post I talk about setting up and securely operating development tools like Jenkins and Gitlab on a server connected to the internet. All applications run behind a firewall and a reverse HTTP proxy which allows only HTTP requests from selected users through who authenticate themselves with client certificates. Putting web-facing software on the … Continue reading Securing a development server
I started quite a while ago moving a pet project to ip6. While it doesn't involve any programming per se, it turned out to be quite a complicated process involving multiple configuration steps. Thus, for your enjoyment I present: running a website on ip6 with Ubuntu 14.04 (older versions won't work because their kernel doesn't … Continue reading Running a website on ip6
In many larger WLAN setups you'll find repeaters or extenders which spread the WLAN to farther places on the floor. Often they are set up in such a way that they use the same WLAN name (SSID) and password. In that case the WLAN hardware on your laptop will pick the best access point and … Continue reading Linux picking the best access point in a WLAN with repeaters
As I am a frequent guest in public WLANs I spent some time looking into ways to connect safely to both the corporate network and the rest of the internet while enjoying the amenities of a cafés' or hotel's wifi. Because of its simplicity and universal availability I like SSH tunnels which are easily set … Continue reading Automatically starting an SSH tunnel in Ubuntu
A while ago I noticed that Firebug would report 40-100ms DNS lookups for sites that could not possibly not be in the local DNS. When reloading a page that had just been rendered, the same DNS lookup delays would show up over and over. I could not verify whether it's an issue with my ISP … Continue reading Installing a local DNS cache on Ubuntu 11.10
Over the course of my involvement [1] in my Indonesian company's website, the question of how to design a website to deal with slow and bad network links presented itself over several occasions as most of our users surf either over a mobile connection or a similarly dimensioned fixed line. While optimizing design and resources … Continue reading The impact of network packet loss on HTTP latency
Windows handles NETBIOS server names just like any other DNS entry, so you can ping, http:// or ftp to any computer on your Windows network. While Linux binds those computers also via Samba, it does not export that information to the rest of the networking stack, i.e. this will fail: ping win7machine This post [1] … Continue reading Resolving smb server names in Linux
Recently I conducted a load test on my beloved low end Ubuntu 8.04 VPS. The setup consists of a mysql 5.1 DB, a Tomcat 6 webapp, openjdk 6 and Varnish 2.1.2. The load generator was issuing HTTP GET requests through a DSL connection which were supposed to create a decent load on Tomcat. To my … Continue reading Varnish, session_linger and dropped connections
