scponly, rsync and Fedora

A few years ago I wrote about the backup script that I use to do daily and weekly backups of my computers. Since this script must run unattended it makes use of a passphrase-less SSH key. The SSH key in question only exists on my main workstation and is used to login as a user which does not own any other files. While this isn’t a big security problem it would be nice to limit the privileges of this user. To this end I started using scponly some time ago. Scponly is a restricted shell which limits a logged in user to only executing a few commands such as scp, sftp and rsync. This small set of available programs greatly reduces the chances that the user will be able to find a local exploit. Scponly is already packaged for Fedora so installing it is simple.

yum install scponly

Setting an user’s shell to scponly is accomplished with the usermod command.

usermod -s /usr/bin/scponly backup

Like any shell, scponly must also be added to /etc/shells. Just add “/usr/bin/scponly” (without the quotes) to the end of this file.

As I mentioned when describing the backup script, the script works great except for large amounts of data such as media collections. Over time my photo collection has grown to over nine thousand images and now consumes more than eighteen gigabytes of disk space. So today I decided to cron up rsync to synchronize my photos to the same location where my backups are sent every night. Unlike my backup script, rsync will only send the changes to the remote server not the entire archive.

After much debugging I discovered that the most recently released version of scponly does not work with rsync. The thread where this problem was first discussed started in March 2006. More related posts can be found in subsequent months. Fortunately the scponly authors have fixed this bug in their CVS repository so I built a RPM for the CVS version.

scponly-4.7CVS20071229-1.fc8.x86_64.rpm

scponly-debuginfo-4.7CVS20071229-1.fc8.x86_64.rpm

scponly-4.7CVS20071229-1.fc8.src.rpm

This package successfully upgrades the scponly package provided by Fedora. Hopefully these RPMs are useful to someone.

Downloading source RPMs in Fedora

The main yum executable doesn’t have an option for downloading source RPMs. Fortunately, this task is made easy by yumdownloader which can be found in the yum-utils package.

yum install yum-utils
yumdownloader --source scponly

This will leave a copy of the scponly source RPM in the current directory.

Ontario Linux Fest

This past Saturday I spent the day at the Ontario Linux Fest which was held at the Toronto Congress Centre. Despite this being the inaugural year for the event it was very well organized and I think, well attended. The number I heard was approximately 350 attendees. The most enjoyable aspect of the event was that it had a really nice community feel. Everywhere you looked there were groups of people chatting and having a good time. The only negative thing I can say is that many of the presentations were very high level. Given the broad audience this is not necessarily a bad thing but personally I was hoping for more technical detail. I really hope the organizers are able to this again next year because I’ll definitely be there.

I didn’t have a real camera along so the best I can offer is this picture of Jon ‘maddog’ Hall‘s closing presentation taken with my N800.

Picture from the Ontario Linux Fest

Torvalds interview

Q&A: Torvalds on Linux, Microsoft, software’s future

CW: Lots of researchers made millions with new computer technologies, but you preferred to keep developing Linux. Don’t you feel you missed the chance of a lifetime by not creating a proprietary Linux?

Torvalds: No, really. First off, I’m actually perfectly well off. I live in a good-sized house, with a nice yard, with deer occasionally showing up and eating the roses (my wife likes the roses more, I like the deer more, so we don’t really mind). I’ve got three kids, and I know I can pay for their education. What more do I need? . . . So instead, I have a very good life, doing something that I think is really interesting, and something that I think actually matters for people, not just me. And that makes me feel good.

Ottawa, OLS and the war museum

Arrived in Ottawa today for OLS. Managed to get in early enough to make it over to the new (2005?) Canadian War Museum. Unfortunately, there was only two hours left before close. Two hours was not nearly long enough to do the museum justice. Even if you have been to the previous war museum you should go again. The new building is gorgeous and there is lot more stuff to look at. If you like to read everything in a museum, you need to budget a LOT more than two hours.

For those new to Ottawa, walking to the war museum from OLS will take under 30 minutes.

Photo 20060718-cwm-1.jpg from the Canadian war museum
Photo 20060718-cwm-2.jpg from the Canadian war museum
Photo 20060718-cwm-3.jpg from the Canadian war museum
Photo 20060718-cwm-4.jpg from the Canadian war museum
Photo 20060718-cwm-5.jpg from the Canadian war museum
Photo 20060718-cwm-6.jpg from the Canadian war museum
Photo 20060718-cwm-7.jpg from the Canadian war museum
Photo 20060718-cwm-8.jpg from the Canadian war museum
Photo 20060718-cwm-9.jpg from the Canadian war museum
Photo 20060718-cwm-10.jpg from the Canadian war museum

RedHat summit videos

Red Hat has posted videos of the keynotes from the Red Hat summit in Nashville. So far, I have only watched two of the three videos. Both were excellent.

Eben Moglen: Discusses the philosophical and political ideas behind free software. He argues that free software is about allowing individual creativity. If you don’t ‘get’ free software you need to watch this speech.

Cory Doctorow: Provides a bit of history on copyright change and how the incumbent industries always try to stop progress. Lots of good DRM discussion as well.

There is no future in which bits will be harder to copy than they are today … Any business model that based on the idea that bits will be harder to copy is doomed. [Cory Doctorow (2006 RedHat summit in Nashville)]

I found both of these speeches to be inspiring. Free software is the start of a wider revolution. As Moglen says in his keynote (paraphrasing), it is an incredible privilege to live through a revolution.

Linux and proprietary (graphics) drivers

From New Linux look fuels old debate:

For Nvidia, intellectual property is a secondary issue. “It’s so hard to write a graphics driver that open-sourcing it would not help,” said Andrew Fear, Nvidia’s software product manager. In addition, customers aren’t asking for open-source drivers, he said.

The open-source community already maintains many drivers. Even if NVidia’s drivers are somehow better at present, I bet NVidia would be very surprised how quickly the community would improve them. “It’s so hard to write a graphics driver that open-sourcing it would not help,” sounds like something people would have said about building a high-quality operating system like Linux 10 years ago.

Secondly, as an NVidia customer, I am asking for open-source drivers. I am sick of the driver dance that closed drivers force me to go through. I want my graphics driver to be packaged and updated as necessary by my distribution just like the rest of my system. I want an open-source driver so that the Xorg developers can modify the driver to take advantage of new features and architectural changes. As the speed of development on Xorg increases (which appears to be the case in recent history) proprietary drivers are going to have more difficulty keeping pace.

The next graphics card I buy will have good open-source drivers, even if it slower than the alternative with proprietary drivers. From the article linked above, it looks like it may use an Intel graphics chip.

Note: If you don’t understand why the Linux kernel developers dislike the idea of closed-source drivers so much you should read Linux in a binary world… a doomsday scenario by Arjan van de Ven (also linked to in the quoted article).

Linux Journal’s new editor

So my favourite magazine, Linux Journal, has a new editor. Nicholas Petreley.

I have been a Linux Journal subscriber for 8+ years and I proudly have every issue on my bookshelf. I even paid for a subscription for my favourite computer store to help them gain knowledge about Linux and FOSS.

It used to be that the final page of Linux Journal had good information; news from the community, law advice etc. Now that Petreley has joined, the last page of my favourite magazine has uninformed rants that at best belong in a Slashdot comment on a KDE vs GNOME story.

I can only imagine what people new to the community will think when they pick up their first issue of Linux Journal and see that the writing style typified by Slashdot comments also makes it into the community’s print publication.

I will reserve my judgement on the article content for a couple of more issues since the articles that have been published so far were quite likely in the pipeline before Petreley got involved. However, I seriously doubt that Petreley’s biases will not bleed into the rest of the magazine.

On the plus side, the new larger, more graphical layout is quite visually appealing. To whatever extent Petreley was involved in the graphic design changes I compliment him and the rest of the Linux Journal team. Too bad the new layout does not make up for the loss in editorial quality.

The modernization of X

For those who don’t know, there is a lot of good work happening on X these days. Especially interesting is Xgl, AIGLX and the composite extension. Since Xgl and AIGLX are two different ways to bring GL-accelerated effects to the standard Linux desktop, there has been much arguing over which is the better approach.

NVidia appears to believe that the AIGLX approach is a better long-term solution but there is no denying that the combination of Xgl and compiz produce better results at present.

Despite reading extensively on both of these projects, I don’t know enough about deep graphics issues to really make a good decision as to which is better. I’ll leave that to the X people. For now, I’m just really happy to see these features coming to my Linux desktop soon!

Check out this video from Novell to see just how cool this stuff is.

Xgl demo (58MB, XVid).