Mozilla Printers List continuously Reloads, and alternately shows a Network Printer as Existing and Not.

I recently ran into an error condition, in which on my Linux laptop ‘Klystron’, I had pulled up a Printers List within Firefox, to Print out a Web-page. And the list of available printers kept updating, alternately with a network printer displayed as existing, and with the same printer missing, just over once per second.

I was able to get to the root of this problem.

I had recently installed the package ‘avahi-daemon’ on that laptop, prior to which that error condition did not occur. ‘avahi’ is a service-discovery daemon, which means that it scans the network neighborhood, and makes shared resources visible in the lists of GUI applications, where those resources might normally not be visible under Linux.

The cause of this problem seems to be, that if more than one resource exists by the same name, Firefox will continuously be in a state of confusion, about the fact that both resources should exist side-by-side.

For example, it is possible to have a printer named ‘PIXMA_MX922′, which is a WiFi-printer and which is therefore accessible directly on the LAN, by way of the router. It could be installed directly on all the computers by way of CUPS. But at the same time it is possible to have a server set up which is named ‘Phoenix’, the CUPS service of which has that printer installed directly, as well as having the ‘Samba server’ installed, which offers to share all the local printers as a Samba share by the same name, by default.

Next, if we have a laptop named ‘Klystron’, which is running the ‘avahi-daemon’, then according to its new discovery capabilities, there are at least two printers on the same network,

  • ‘PIXMA_MX922 As installed on the LAN’ and
  • ‘PIXMA_MX922 As belonging to the Samba server Phoenix’

As far as I can tell, the problem here is that both printers will have the same name, because the Samba server serves it out as having the same name it had locally with its own CUPS server. And at that point, the Available Printers List belonging to Firefox becomes unstable.

There is more than one way to solve this problem.

Continue reading Mozilla Printers List continuously Reloads, and alternately shows a Network Printer as Existing and Not.

Some GPU Stats about Two Of My Computers

I own a Windows 7 tower-computer I name ‘Mithral’, which has an NVIDIA GeForce GTX460 graphics card. That was state-of-the-art around 2011. I read that its GPU was identical to that of the GTX470, except that the GPU was supposed to possess 8 core-groups. In the factory, they tested the GPUs, and if they found that one of the core-groups was defective, they used a laser to deactivate that one, and sold the graphics card for a lower price, as a GTX460. According to the first screen-shot, which was obtained using “GPU-Z”, it has 7 * 48 = 336 cores.

I also own a Linux-based laptop named ‘Klystron’, with a nonspecific AMD / ATI chipset – both CPU and GPU – which was state-of-the-art around 2013. The second and third attachment seem to show that it possesses 6 * 64 = 384 cores. The second screen-shot was obtained using “KInfoCenter”, and the last text-quotation was obtained from the OpenCL toolkit installed on the same laptop.

Continue reading Some GPU Stats about Two Of My Computers

Experimenting with Tor

I own an old, beat-up laptop I name ‘Venus’, from circa 2005. And with this laptop, I am exploring the fantasy that it should be configured to connect to the Internet, entirely using ‘Tor‘. I am trying to replicate what the TAILS USB-stick is said to do, but in the hopes that my own achievements will be more credible. You see, I doubt that TAILS really accomplishes what it claims to accomplish.

I have to admit, that I really have no idea, what that old laptop is supposed to do, once it is connected via Tor. This just seems like a fun project. And, there exist few services today, which will just let people connect via Tor. What one can do is browse, using a Web-browser, and not use Google, because the geolocation services of Google tend to blacklist most of the exit nodes of Tor.

But, wanting one additional ability, I also decided that Venus should connect to a less-important email server of mine via IMAP, and through Tor. What I discovered, was that the email client I was using for this does not itself support a Socks 5 Proxy, through its own GUI. And so I read that some command-line utilities exist for Linux, which will force the programs specified to use such a proxy.

The first utility I tried was called ‘proxychains’. But there is a caveat with this utility, that people fail to point out. It will negotiate the email client to connect to Port 143 in plain-text, rather than in cipher-text. I had not noticed this, until my laptop had connected to my email service, in plain-text in fact. This means that a corrupt exit node would have been able to sniff my password.

This is the full extent to which I was compromised. There was really no other sign, that anybody might have tried to connect to my (subscribed, paid-for) email server, in my place. But such a single exposure was more than what I was willing to let sit.

So I immediately changed the password of this subscribed, paid-for email service, to a much harder password, before anybody else got the chance, and I am still able to use that email address fully.

But then the question lingers in my head, of how I might nevertheless connect to it via Tor. There exists another command-line utility named ‘tsocks’, which claims to tunnel all the TCP/IP connections of its designated program, through the Socks 5 Proxy, without analyzing what types of authentication may be taking place.

I tried to use tsocks as described, but only found the comforting message, that the stream could not reach the IMAP server in question. So here there was no evidence that the utility in question actually breaks TLS encryption.

But ultimately, I would still not feel comfortable using tsocks, after the experience I had with proxychains, because I need to take the idea that tsocks does not break encrypted protocol, entirely on the words of software-authors who I cannot ultimately trust. These are Tor specialists after all. Even tsocks might eventually compromise my connection-security, even though it is not supposed to.

And so my little Tor laptop remains useless, from any practical perspective.


Continue reading Experimenting with Tor

WiFi on Laptop named Klystron, RTL8723BE

One subject which I have commented on often, but which in recent months I have gotten little or no new information about, was the stability of the WiFi chip-set on my laptop ‘Klystron’, which is driven by the kernel modules known as ‘RTL8732BE’.

Here is an earlier posting on this subject.

Since that posting, there have been 2 firmware updates to that laptop specifically. One, to version 1.159, and the next, to version 1.160.

What I found was that firmware version 1.159 actually seemed to make the WiFi very unstable again – a regression. But firmware version 1.160 seemed to make it stable again.

In the meantime, I have a script in directory


which is intended to deal with A Different Problem that laptop has, which was, that after resuming from sleep, the laptop system clock would seem to jump ahead exactly 68 hours. I had changed that script as an experiment. But now I have changed it back again, to:

# fixing

case "$1" in
    date +%s > /tmp/suspend.log
    was=`cat /tmp/suspend.log`
    now=`date +%s`
    # time shifts for 68 hours
    if ; then
      date -s "`date -R --date="68 hours ago"`"
    /bin/sh -c "sleep 20; /etc/init.d/nmbd restart; /etc/init.d/smbd restart" &

I often did suspect that problems which I had specifically associated with the kernel module, may not in fact stem from the kernel module. On my LAN, I use a router which is not owned by me, but rather by my ISP, and that router has numerous settings – as well as its own Firmware flashing – under the control of my ISP rather than under my direct control.

This router is still useful to me, because I subscribe to “Bell Fibe” and get to watch TV through it, in 1920x1080i resolution, which I could not do, if I was to try switching to a router owned by me.

But many of the problems which Klystron has on my WiFi, may all be policy issues with this router. Since I cannot get deep into the router settings, I am left guessing as to what router policies the laptop may not be abiding by.

But what this can do is lead to Samba problems specifically, which seem to mimic general WiFi connectivity issues, but which are not really examples of that.