LJ Archive


Cheap Android Device for Testing Apps

Some time ago Shawn Powers mentioned having found some device that replaced the Galaxy Player 4. I haven't found the article (again) yet, but I would like to find a cheap Android device to use in playing with Android apps. Can you give me a pointer to the issue where you discussed that, or a pointer to what is on the market that might work?

Bob Rader

Shawn Powers replies: The article was in issue 251, March 2015. I haven't looked at it in a while, and although conceptually, I'm sure it's still valid, the phones listed are way outdated. I'm currently using a Sony Xperia Z5 Compact, which is also a bit outdated, but it still works fast enough for playing audio and such. I actually had Cricket Wireless service on the phone for a few months, but I let that expire and just use it with Wi-Fi now. I'm extremely happy with the device after rooting it. I went with the Z5 because it was small, but if size isn't an issue, any Android phone from a generation or two back would be more than adequate for such things. Just do research in advance to make sure it's easy to root, because that is essential for most nerdy endeavors!

BYOC Part III, Replacing btools with ClusterShell

In the very interesting articles about building your own cluster (see the “BYOC” series by Nathan R. Vance, Michael L. Poublon and William F. Polik in the May, June and July 2017 issues), the authors described writing some tools to reach all nodes from the cluster, the Btools scripts. I would suggest giving a try to ClusterShell, which is a Python tool and library to connect, through ssh, a big set of nodes in parallel. It also provides remote copy and so on:

bexec <command> -> clush -a <command>
bpush <file> <destfile>-> clush -a --copy <file> [--dest <destfile>]

See cea-hpc.github.io/clustershell.

Aurélien Cedeyn

Nathan Vance, Michael Poublon and William Polik reply: Thanks for your interest in cluster computing. There are excellent packages for administering nodes on a production cluster, such as ClusterShell (clush) or Cluster Command & Control (C3). The purpose of btools is to demonstrate a minimal, self-contained set of tools for cluster management. Any Linux users can then understand what is happening under the hood when they “Build Your Own Cluster (BYOC)”!

A General Request

I wrote about Linux in the past (a long time ago). I would just strongly encourage the Linux community to try to debug old problems rather than make new software and jump on new distributions. It has been an observation of mine that although Linux does work on almost anything, the turnover is too fast for most humans to keep up with.

Sujan Swearingen

Shawn Powers replies: I understand and largely agree with your sentiment. As someone who has “re-invented the wheel” a few times, however, I can attest that sometimes figuring out someone else's work takes more time than starting from scratch. That's not necessarily the fault of the original developer. As busy geeks, we tend to take the avenue of least resistance, and unfortunately, that often means leaving a trail of destruction and abandonment in our wake. Yours is a good reminder though that open source was built on the shoulders of those who came before. If we can build on the success of someone else, it will make an even better product in the end.


I'd like to inform you about this project: https://puri.sm/shop/librem-5.

I value it as a awesome project for Linux, Linux users and freedom. I'd like to see an article on it, and I really hope its crowdfunding will have success. Thanks for reading this.


Shawn Powers replies: I'm pretty sure that LJ columnist Kyle Rankin is chairman of the advisory board for that company. I know Kyle uses Purism laptops, and he has at least mentioned them from time to time in articles (search for “Purism” on www.linuxjournal.com to find them). Nevertheless, you're correct; Purism is awesome and deserves attention!

Comments on Charles Fisher's inotify Article

Having needed to solve a similar problem in the past, I was very interested to read Charles Fisher's article (“Linux Filesystem Events with inotify”) in the August 2017 issue. However, I noticed one problem with it that needs clarification. Twice in the text he states that inotify can't monitor remote, network-mounted filesystems, such as NFS. This is not entirely true. inotify can report on filesystem changes on an NFS-mounted filesystem, but only for the file activity on the system on which those changes are being made, just like a local filesystem. It will not report on remotely generated events (for example, a file being manipulated on the NFS share by another server).

Todd Campbell

Charles Fisher responds: Assuming that the remote NFS server is running Linux, this seems reasonable (although I have not tested it). There have been several Linux NFS implementations, starting with the user-space server in the 1990s and proceeding through all the protocol versions as they were introduced and implemented in the kernel. I'd be confident that inotify would function properly in most of them, but not certain.

Obviously, any other file sharing protocol will have even bigger problems (for example, SMB), and if the remote server is not Linux, inotify is not a workable tool. I might also point out that one of my mentions of this was a direct quote from a systemd manual page, and it might be a hard sell to get that changed.

Banana Backup Article

I much enjoyed Kyle Rankin's “Banana Backups” article on using Banana Pi and a 2.5" drive for backups in the September 2017 issue. It's a really good idea. Another suggestion for the software is storeBackup. I have been using it on both my personal Bodhi Linux laptop where I do my daily work as well as on the little home server I run on an old Toshiba Satellite laptop.

The little server runs ownCloud, SubSonic, caliber-server, MySQL and a few other smaller services. ownCloud has a fair amount of data, including all my contacts, calendar, legal documents photos and music. So it's a lot of stuff that I don't want to lose.

storeBackup is a Perl application that is very simple to set up with a single configuration file, great documentation (downloadable or online), and it's simple to install. It has been a rock-solid performer for me. It uses hard links and compression to reduce disk storage size.

I won't say it is better than any other backup software, but if one likes Linux and Perl and open source, it is a solid solution in my experience and worth mentioning.

Thanks for an excellent article in an always excellent magazine!

Wes Wieland

It's Time for a Linux Live CD That Works for Netflix

I just spent the past month watching Amazon Prime Video using a Linux Mint 18.1 Live CD (no HDD exposed to the internet).

I only had to install npapi to get around the DRM requirement. This setup worked for three of the four weeks during the one-month free trial, but then it stopped working for some unknown reason.

Perhaps, it's time for a Linux version of its Live CD that is specifically configured to work for Netflix or Amazon Prime Video without any configuration—it would be very helpful to us users.

Is there an article here for discussion?


Shawn Powers replies: DRM is the bane of our open-source hearts, isn't it? I get so frustrated trying to make such things work on my system, that I have resorted to using apps and/or devices like Roku in order to watch streaming media. Well, honestly, I usually use Plex to stream media, but that requires an entire DVR system, which sort of takes away the whole point of Netflix, Hulu, Amazon Video and so on. I don't have a great answer, other than perhaps resort to a tablet with an Android app, as those are almost always going to be updated and will work well. I wish I was more help!

Linux Live CD with VPN Included

Greetings, I surf the internet with a Mint CD without using a hard drive. I now require the use of a VPN.

What are my options? (Also there doesn't appear to be any company selling a VPN for this scenario.)

When the above was posted on a Mint help chat session, these were the responses:

  • Time to learn “iso” making.

  • Mint suggests a VPN service on its web page.

  • Persistence install may help.

  • In principle, it is possible to create/modify the cd image to include this, but it takes some effort; alternatively, you can create a USB Flash drive version with some persistent memory and install OpenVPN on that.

Now, I didn't really want to use a different Linux distribution just to get the included VPN application.

Also, my concern with using a USB Flash drive is that it could be easily hacked, since it is not read-only, correct?

Anyway, this could make for a good article, right?

I look forward to hearing back from you with some good insight on a solution to my dilemma!


Shawn Powers replies: Stephen, like your Netflix question, I don't have a perfect answer. Rather than a live CD or a USB drive, perhaps a distribution like Qubes would work for you? I realize that's switching distributions, which you wanted to avoid, but if security is a concern, it might be worth considering. Apart from that, I think the USB drive with persistence is the best option.

Firewall Help?

I am looking for a gigabit firewall to put between my ISP provider's modem and my internal network. Although the ISP modem contains a firewall, it is not so secure as others or as a custom firewall.

Maybe a project for later with these goals:

  • Maintaining the throughput of 1 gigabit.

  • Allowing video signals from IP cameras to pass.

  • Dynamically blocking intrusion on different ports.

  • Blocking defective UDP and TCP packets, and IPs from outside with inside IPs.

  • Blocking traffic if not generated from inside network.

  • Allowing VPN network and server.

I was looking for commercial firewalls with a reasonable price, but I found only licensed firewalls that did not fulfill my expectations for a private firewall at home.

Patrick Op de Beeck

Shawn Powers replies: Although certainly possible with Linux, I have to admit for instances like this, I usually go to pfSense. It's BSD-based, but it has a very powerful interface and an even more powerful system beneath. It's open source and free to install anywhere. The company does sell hardware through a partner, but the firewall can be installed on any system. If you do something on your own, maybe pitch the idea to us at info@linuxjournal.com; perhaps your experience will make a good article!

LJ Archive