Letters

Twitter

I'm with Kyle Rankin on Twitter, and what is more, I have tried it [see Kyle Rankin and Bill Childers' Point/Counterpoint debate on Twitter in the August 2009 issue]. As far as I have found, at least 90%, probably 99%, of content is pointless and uninteresting, even from the few people that I know. Reading the drivel of strangers is even more time-wasting. What I am doing now is usually private and personal—not even for sharing with friends, let alone with, potentially, the whole world.

Several years ago, I gave up all forms of instant messaging. I am not prepared to react instantly to the needs of others. If people want to contact me, they can send me e-mail, and I will reply when I feel like it. There is no need for anything to be instant. I stopped answering the telephone six years ago and have not died from the lack of instant contact. In fact, it is quiet peaceful.

—
Rhian Geleick

I envy your ability to shut out the “on call” structure so many of us are required to live out. That said, Twitter either can be useful or it can be a time suck. The same thing can be said for tons of everyday things we use: cell phones, e-mail, instant messaging, books, food and so on. I'm not suggesting a person would die without Twitter (unlike with food), but I say, if it's useful, use it. If not, don't.—Ed.

Dropbox

I just received my August 2009 LJ and noticed that next month, Cross-Platform Development is the topic. I recently came across a cool app that helps share files across cross-platform OSes without a hitch. It is called Dropbox (www.getdropbox.com). They have installs for Linux, MS and Apple. I actually can share files in my Virtual Machine with my host, without having to make sure that the file shares are set up properly.

They offer a 2GB account for free subscribers, and you can access your files from their “cloud” from any computer that has Internet access. For larger groups, they have options for paid accounts with larger space provisions.

You guys are still the highlight to my trips to the mailbox each month! Keep it up!

—
soosurfer

You're absolutely right. Dropbox is one of those nifty apps that is indeed cross-platform and largely relies on Internet-hosted services. It's not quite a Web-based app, but leverages the Internet as a means to communicate. We demonstrated the virtues of Dropbox on our Web site as well: www.linuxjournal.com/video/dropbox-linux. It's an awesome tool!—Ed.

Using banner Instead of motd for Legal Text

In the article “Right Command, Wrong Server” [July 2009], Kyle Rankin mentioned adding a legal warning to the message of the day to be delivered to users after they log in. For legal warnings, I believe the sshd banner option would be more appropriate. The banner is presented to users before a successful login, so people are warned well before they gain access to the system. Edit the /etc/ssh/sshd_config (or distro-specific sshd_config location), and uncomment the following line:

Banner /etc/issue.net

Then create the text file (/etc/issue.net) that contains your legal warnings to be presented to users before they even attempt to log in. Remember to restart sshd to apply the change.

—
Kevin Benton

Kyle Rankin replies: Thanks for the tip! IANAL, so I'm not even sure how effective these notices are in a court of law. I recommend checking with a lawyer to see how enforceable these notices are before you do a system-wide deployment.

Help with MyBook Hack

I am an LJ subscriber, and I was so inspired by Federico Lucifredi's article “Hacking Your Portable Linux Server” in the July 2009 issue that I searched eBay until I was able to buy my own WD MyBook WE NAS drive [MDL:WD10000G032-001]. On eBay, it was advertised as WDG1NC10000N World Edition 1TB. I don't know yet if there is any subtle difference between these models. It arrived three days ago, and without trouble, my browser brought up the WD Shared Storage Manager Web interface, reporting firmware version 2.00.15. As an upgrade was available, I immediately upgraded to 2.00.18. I easily followed your article's instructions and used Martin Hinner's script to set up SSH and then log in from a terminal on my PC running Linux Mint. (Shared Storage Manager gave the “update has failed” message that you mentioned, as expected with this latest firmware.) I switched to root, made ssh permanent through inittab, and disabled MioNet (line 19 in my post_network_start.sh) and also verified that my kernel was 2.6.17.14. I logged out, rebooted, logged back in, and yes, ssh was permanent. So far so good. Martin Hinner also provided instructions to install nano, an alternative text editor to vi, so I used wget to obtain the ncurses-5.7 (required by nano) and nano-2.09 tarballs and untarred them. When I tried ./configure for ncurses-5.7, I hit a wall! It reported “gcc no, cc no, no acceptable cc found in $PATH.”

As I understand it, the problem is (at least) that there is no gcc compiler on this MyBook. I have checked almost every directory, and it's certainly not in /usr/bin or /usr/sbin or anywhere else that I can see. So my question is, how can I install a gcc ARM9 compiler? I will need to obtain it as a compatible binary and install it, so gcc source doesn't help me unless I need to first cross-compile on my Linux Mint PC and then transfer from there. This is less important, but it would be interesting to know: when did WD stop including gcc? If I hadn't upgraded from 2.00.15 to 2.00.18, would the compiler still have been there? Could it be a subtle difference between my WD10000G032-001 and the WDG1NC10000N? Could Martin Hinner's scripts or anything else I did have deleted gcc? I am stuck and can't make any progress until I get a working compiler.

Your article mentioned the presence of gcc3.4.2, gmake, wget and so on, and it gave output for df -h (same as mine) and cat /proc/mdstat (the same except for md4, as mine is a single disk 1TB). Everything seems to check out except the presence of the gcc compiler. Any help with my problem would be so appreciated, and a follow-up MyBook article also would be great.

—
JR

Federico Lucifredi replies: The WDG1NC10000N is a single-drive “Blue LED” WD Mybook World Edition, and it has hardware matching what is described in the article.

Your trouble arises from the 2.x firmware. Although the 1.x firmware versions include the full GCC toolchain, I recently upgraded one of my devices and found that GCC is missing in the more recent firmware.

I ignore the reason for the change (indeed, Western Digital endorsed direct access to Linux in the latest “White LED” devices, where root ssh access can be configured straight off the Web interface), but you have two options for recovery: heading over to the MyBook Community Wiki (mybookworld.wikidot.com/forum/t-50241/tutorial:how-to-recover-gcc-after-firmware-2-00-15-upgrade) for recovery instructions would be the first. The alternative is for you to build a cross-compiling toolchain, which is more involved but certainly convenient, as this way you can build your software for beefier machines. If you choose this latter approach, O'Reilly's Building Embedded Linux Systems is your best introduction.

I also want to note that ipkg (mybookworld.wikidot.com/optware) is on its way to the MyBook. Look for prebuilt packages before you rebuild everything yourself.

There is certainly more that can be said in the subject. I will consider a follow-up article if the interest is there.

Squid Correction

I've been waiting for the last installment of Mick Bauer's “Building a Secure Squid Web Proxy” series [see the May through August 2009 Paranoid Penguin columns] since it was announced back in the April issue. Linux Journal is one of the magazines I read from front to back, and I enjoy it.

I noticed a couple errors in the last article of the series [August 2009]. One is in the instructions to install the blacklists with the --strip argument for the tar command. The code states --strip 1 and the explanation states --strip 2. The other error is in the “Configuring Squid to Use squidGuard” section at the end of the fourth paragraph. The last word should be changed from url_rewrite_program to url_rewrite_children.

One more feature that could be added to this series is how to configure squid as a transparent proxy. I think that a lot of us use Linux or other *nix systems as a firewall to protect home or other networks. When using a transparent proxy, there is no need to configure browsers. There is also protection from other applications that might be accessing banned sites. Keep up the good work.

—
jschiavon

A Suggestion

I have been a subscriber for a long time. If you must cover proprietary products as well, please go right ahead. But, the least you can do when you write such an article is to mention the license in a little space under the title, or at least mention there whether a product is FLOSS or not; it will save many readers like me the time we spend finding out the same for ourselves.

Even if I were not philosophically opposed to proprietary products, installing third-party products on my servers is more pain in the long run than it's worth, not to mention a security risk.

—
Dave

Great suggestion. We'll do our best to clarify licenses when dealing with products.—Ed.

Dracula Correction

Your pipeline of tr and grep has the unintended consequence of eliminating any words that contain, are followed, or are preceded by punctuation [see Dave Taylor's “Looking More Closely at Letter and Word Usage” in the August 2009 issue]. This is not an insignificant number, as it eliminates the last word of every sentence and comma-separated clauses, plus the first and last word of quotations, contractions and hyphenated words.

Using the alternative pipeline, I mentioned a few issues back [see the July 2009 Letters section]:

tr '[:upper:]' '[:lower:]' | tr -cs '[:lower:]' '\n'

the word count of the Dracula text increased by more than 20%.

However, this pipeline results in a different error. Contractions, such as o'clock and didn't, get split into multiple words. The Dracula text contains many unusual contractions such as y'are, Ye'll, a'hidin' and gard'ners. Some strange words result when they are split.

—
Jon

Dave Taylor replies: You're talking about this code snippet:

$ cat dracula.txt | tr ' ' '\
' | grep -v '[^[:alpha:]]' | grep -v "^$"

And you're exactly right. I can't believe I didn't notice that! Thanks for the correction, Jon!

Photo of the Month

Have a photo you'd like to share with LJ readers? Send your submission to publisher@linuxjournal.com. If we run yours in the magazine, we'll send you a free T-shirt.

Bringing Tux Along for the Ride—Submitted by Bill Parducci