In the good old fixed line SIP world things are straight forward when a SIP user wants to call someone: INVITE, TRYING, RINGING, OK and you are there. In the VoLTE world things are a bit more complicated as the service tries to replicate the circuit switched telephony service. Here, a media stream can already sent before the receiving party answers the call so the caller hears an alerting (ringing) tone or even music in some cases. This is what’s known as early media in VoLTE and there are two ways how this is done in practice:
How Fast Is That SSD In My Notebook?
In theory the 1 terabyte Samsung 840 Evo SSD I use in my notebook has a sustained write performance of well over 400 MB/s according to this fabulous review over at Anandtech. That is two thirds of the theoretical maximum speed the SATA 3 interface can deliver. While this is all nice and well I wondered how fast the SSD would be in combination with my notebook and my typical usage scenarios.
Pushing My Owncloud File Size To 3 GB
By default, Owncloud is configured to handle files up to a size of 512 MB. While that’s probably good enough for most, I do run into this limit rather often. There are instructions how to increase the limit from an Owncloud point of view but when I recently wanted to transfer a 2.7 GB file my setup failed outside of Owncloud. It took me a bit before I found out how to fix it so I thought I put together all things I have now learned about how to configure a system for large file transfers in Owncloud with a number of security and privacy tips thrown in for good measure.
Time To Switch From Opera to Firefox On Mobile – At Least For Me
Ever since I discovered last year that Opera’s web browser on my smartphone was responsible for strange queries to my web server from China to generate a thumbnail image (see ‘When Opera Calls From China‘) it had been at the back of my mind that Opera is not open source and hence I have little trust in it. These days it also seems like Opera is going to be sold to a Chinese consortium which would make it even less attractive for me to continue using it. Time to change to another browser on my Android based devices then. How about Firefox?
Continue reading Time To Switch From Opera to Firefox On Mobile – At Least For Me
MouseJack Vulnerability – Have You Already Patched Your Mouse?
Quite strange that only Bruce Schneier has picked up on this so far but researches have developed a proof of concept of how to exploit HID (Human Interface Device) USB dongles for wireless mice and keyboards to accept keystrokes from rouge third party transmitters.
Continue reading MouseJack Vulnerability – Have You Already Patched Your Mouse?
Eduroaming in Utrecht
Eduroam is a great Wi-Fi login system for students and researches that works with certificates for secure access of on-campus Wi-Fi networks and has the added benefit that Eduroam users can attach to any other Eduroam network around the globe without changing their Wi-Fi configuration. That’s the theory and paper is patient. So when I recently was at the University of Utrecht in the Netherlands I tested if the theory holds up with an Eduroam setup of the University of Vienna.
What Is My Theoretical Top Internet Speed?
Theoretical Internet speeds in fixed line and mobile networks keep rising, which is a nice thing. Unfortunately, round trip delay times are not decreasing at the same rate, mostly due to physical limits these days which at some point will limit the maximum throughput of a single TCP stream no matter how fat the pipe is and how fast a server can deliver data. So where is this limit?
The Mysterious IPv6 DNS AAAA-Resolver Bug
In my quest to do as many things over IPv6 now that it’s supported not only by my VDSL line at home but also by my mobile network operator, the last success story I reported here was about how to update my IPv6 DNS entry whenever the dynamic IPv6 address of one of my servers at home changed. The procedure works like a charm but unfortunately I found a big bug in the DNS resolver in my Fritzbox VDSL router that pretty much forestalls my IPv6 home server ambitions for the moment.
Book Review – Inside The Machine
Back in 2013 I published a post on the different levels on which a computing device could be understood from a working level down to the physics behind the individual gates. One facet that has been missing for me so far was a look at the features that make today’s CPUs so powerful. “Inside the Machine” by John Stokes filled that gap for me.
32-bit vs. 64-bit Memory Impact
One downside of moving from 32-bit to 64-bit is that memory pointers are twice their size. In other words programs in memory require more RAM. But does it matter in practice?
To find out I ran the 32-bit version of Ubuntu 14.04 from a USB stick and compared the used and available memory in different situations on the same system when booting from a different memory stick with the 64-bit version of the OS.