All Aboard….

Your JoeDog is coding on the train right now. What’s he coding? He’s adding recursive directory searches to fido.

 

 

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How To Prevent root’s mailbox From Filling With Cron Messages?

So one of your file systems is full and you traced it to a curious phenomena: root’s mailbox is loaded with messages. And you think to yourself, “Who the hell is sending mail to root?” Chances are, it’s you!

This recently happened to a friend who’s new to Linux. Root’s mailbox was full of messages that looked like this:

/bin/sh: ntpdate: not found

It turns out he had a cron job that ran ntpdate to sync his system time with a server at the National Institute of Standards. (Here’s a complete list of NIST time servers.)

The program ‘ntpdate’ was located in /usr/bin which was not in root’s PATH. So here is lesson number one: Always use the full path to a program in cron. In this case, he should have used /usr/bin/ntpdate.

Now about those mail messages. When a cron job fails, it captures the program’s output and mails it to the cron owner. If you set /bin/ls to run every five minutes in cron, you’re going to get a directory listing in your mailbox every five minutes. You can silence cron and stop mail messages by redirecting output to /dev/null. The ‘>’ character means ‘redirect’ Here’s the syntax: /bin/ls > /dev/null

Yet that wouldn’t have helped Your JoeDog’s friend. In his case, the offending message was an error message. Error messages are written to a different file descriptor.

The Linux/UNIX shell has three file descriptors: stdin, stdout and stderr. ‘/bin/sh: ntpdate: not found’ was written to stderr. In the shell, 1 represents stdout and 2 represents stderr. To capture both we need another character. ‘&’ means file descriptor. So 2>&1 means redirect stderr (2) to whatever stdout (1) points to. Here’s the syntax he should have used:

0 */6 * * * /usr/bin/ntpdate nist1-pa.ustiming.org > /dev/null 2>&1

Now Your JoeDog has been in this game for quite a while. In the day, to really silence the crontab we’d write the redirect like this:

0 */6 * * * /usr/bin/ntpdate nist1-pa.ustiming.org 1 >/dev/null 2>&1

That’s basically the same as the first one but it seemed to work around oddities and keep our mailboxes clean. The crontab man page still contains that syntax. Your JoeDog will continue to use that superfluous first 1 but your mileage may vary.

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When Customers Don’t Want Their App Purchases Tracked

  1. “I beg of you” please delete my name from the app purchase list.
  2. Wifi Wars or how to express your views with SSIDs
  3. Is your wifi SSID a security risk?
  4. Apple keeps Steve Jobs’ empty office untouched
  5. And now we wait: Net Neutrality Considered
  6. Before computers, people programmed looms

 

 

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Linux Bare Metal Recovery With Rear

Your JoeDog loves rear! And who doesn’t, amirite?

Except it’s not that rear. It’s an acronym for Relax and Recover, a Linux bare metal recovery tool.

Your JoeDog has been using Mondo for cloning systems. It’s good software that served him well despite difficulties moving from one hardware set to another. If Your JoeDog archived sd disks and recovered to cciss, then he was knee deep in i-want-my-lvm hell.

Rear makes those type of migrations much easier. If you archive a server using one type of disk driver and recover it to one that requires another, rear reworks the disk layout for you. It’s also configured to ignore external disks. If you archive a server connected to a SAN, rear simply ignores those multipath devices.

Like Mondo, you can archive and recover from an NFS server. Here’s a suggested configuration for NFS archiving. Place these directives inside /etc/rear/local.conf

OUTPUT=ISO
BACKUP=NETFS
NETFS_URL=nfs://10.37.72.44/export
NETFS_OPTIONS=rw,nolock,noatime
OUTPUT_URL=file:///export

To archive the system, run ‘rear -v mkbackup’

This configuration creates an ISO image called ‘rear-hostname.iso’ inside 10.37.72.44/export/hostname. To recover the server, burn that ISO onto a CD and boot the system with it. Select the Recover option then run ‘rear recover’ at the command prompt.

“It’s that simple,” Your JoeDog said with the zeal of a recent convert. He’ll be back to bitch about rear in a couple weeks but for now it’s nothing but love….

Posted in Applications, Rear | Leave a comment



High Tech Depression

The Atlantic has an interesting article about depression and anxiety in the tech industry.

Yet certain elements of startup life and culture may make people particularly susceptible to depression. Stress, uncertainty, youth and isolation—the virtual cornerstones of today’s startup—have all been shown to increase likelihood of developing the disorder.Irregular work hours and constant high stress levels can lead to both social isolation and sleep disturbances, which can aggravate depression and make people even more volatile.It’s almost a perfect storm, says Maurice Ohayon, a professor of psychiatry at Stanford University School of Medicine. “Any psychiatrist can tell you that this population is particularly exposed,” he told me.

Most founders operate under a huge amount of pressure. They are responsible for employees, shareholders, and maintaining company morale, mostly before reaching the age of 30. And especially in the early stages of running a startup, they shoulder that burden mostly alone.

[Atlantic: Tech Has a Depression Problem]

 

 

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A Lock Picking Tool For Sidewinder Locks

 

When Your JoeDog lived in Manhattan his car had traditional locks. Thieves frequently jimmied those locks and took whatever they could find inside the vehicle. One morning before work, he was seen carrying a new battery down Second Avenue after his was stolen the night before.

He finally solved this problem in 1993 by installing a red light below the dash. The light didn’t do anything other than illuminate but thieves figured Your JoeDog had a fancy pants alarm and moved on to the next car.

In 1998, Volkswagen introduced sidewinder keys to thwart lock jimmiers. These keys had a flat metal blade with a wavy groove down the center. They had an identical cut on the reverse so the key could be inserted either way. They were also known as internal cut or laser cut keys.

Starting in October 2000, Volkswagen added a transponder chip for additional security. This type of key is now found on a wide array of vehicles.

The video at the top of this post is generating a stir. It features a lock picking tool for sidewinder locks. After a little fiddling inside the enclosure, the tumblers seem to adjust to the tool and the door opens for the intruder. He’s able to turn the ignition with even less effort. Fortunately, the car doesn’t start. It’s probably looking for a signal from the transponder chip.

So while your car may remain in its parking spot, as Your JoeDog can attest, once thieves gain entry they can wreck your entire morning. A battery gets pretty heavy after just one block. Imagine lugging one for seven more….

[Digg: If You Live In Bangkok Here's How Your Car Will Get Stolen]

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Here’s What We Know About The GMail Hacking Incident

Yesterday there was a flurry of reports about five million hacked GMail accounts that were posted online. A large number of people were understandably alarmed. This is the type of breach that can expose a victim to identity theft.

The GMail credentials first appeared on btcsec.com, a bitcoin security forum. They were posted by someone named TVSkit. He was described as Russian, probably due to his penchant for funny characters since the forum is a Russian language site.

Soon after the initial wave of reports, Google weighed in on its security blog. The company harvested the posted login credentials and checked them against their internal records. According to the company, less than 2% were valid and even fewer could be used to access an account.

In the wake of this report, there was another round of breaking news. Google probably wasn’t hacked but you should probably change your password anyway, the media said as it turned its attention to the next shiny object. No. What you should do is setup two-step verification.

In all likelihood, this stir was caused by an adolescent copy-and-paste hacker who grabbed someone else’s credential sheet and used it to bolster a claim about a non-existent GMail breach.

 

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Happy Internet Slowdown Day!

ajax-loaderYou may see a few more “Loading…” images today. Several prominent companies are participating in Internet Slowdown Day. While they’re not actually throttling their sites, they are featuring those images in order to make a point: without net neutrality, much of the Internets could slow to a crawl.

The demonstration is part of a larger effort to persuade the FCC to enact stronger protections for net neutrality. Some Internet Service Providers would like to create “Fast lanes” in which websites can pay for higher priority and faster traffic. Sites that don’t pay the premium will perform poorer than those that do.  It may surprise you to learn that Your JoeDog doesn’t have pockets as deep as Microsoft. In a fast-lane universe, his site will resemble a sleeping tortoise.

Thus far, more than a million comments were submitted to the FCC. The vast majority of them support net neutrality. You still have time to add your voice. Comments are open until September 15th.

 

 

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Facebook: How To Stop Videos From Playing Automatically

A few months ago, Facebook changed its policy and began setting videos to auto-play. This is particularly annoying on phones and tablets where you can pay for data usage. But it’s also annoying on web browsers. Your JoeDog uses the Vimium plug-in for Chrome which gives him vi-bindings for navigation. He scrolls down with ‘j’ and up with ‘k’. Auto-play breaks vimium. Oh, noes!!1!!!1!

Here’s how to to stop videos from auto-playing on Facebook.

First navigate to Settings. On mobile, it should be an option on the left hand navigation menu. In your browser it’s a little more tricky to find. Look for the privacy menu on the top blue banner. It’s a small menu with a lock:

FB1
 

This will present a Privacy menu. Scroll down to the bottom to “See More Settings”  Click that and it will take you to the Privacy and Tools page. On the left hand side you’ll see a navigation menu. Look for “Videos.” On my nav it’s the last item. That link will take you to Video Settings. From there you can turn off Auto-Play

FB4
Annoyance resolved.

 

 

 

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A Three-Column CSS Layout

Your JoeDog has a new look and feel!

The theme remains the same but we’re rocking a better architecture. The previous version was close to six years old and I made a poor design decision. What was that? I used HTML tables instead of CSS. It was a bad decision then but it’s inexcusable now. Don’t use HTML tables …. ever!

Why’s that?

CSS has numerous advantages over HTML.

  1. It eliminates the need for a clipboard. If somebody refers to you as a copy-and-paste programmer, that’s not a compliment. Redundant code is hard to maintain. CSS allows you to manage pages with a single file.
  2. HTML tables contain large amounts of markup. With CSS, you can reduce much of that, lower your site’s overhead and create faster loading pages.
  3. Site redesign is so much more efficient with CSS because it decouples content from its presentation.
  4. CSS is better for SEO because it boosts your content to code ratio and it better enables you to signal which items you want to emphasize.
  5. And the biggest reason CSS is superior to HTML: NO SPACER.GIFs

Now Your JoeDog is no CSS design expert but he knows what he likes: a header and three columns — one for navigation, one for content and one for ads. You’re not blocking his ads, are you? They help pay the bills.

Fortunately, Matthew James Taylor is a CSS expert. To create this new design, Your JoeDog incorporated his Three-column Holy Grail. Taylor achieves cross platform compatibility and SEO friendliness without resorting to hacks, images or javascript. The design uses 2-1-3 column ordering. So while you’re viewing these words in column number two, search bots are viewing them in column number one. Clever!

I highly recommend his templates. If you’re having difficulty implementing them, feel free to steal code and ideas from this website. (In particular, look for the .main #content tag. Your JoeDog used that to prevent Taylor’s floating blocks from crushing his margins and padding.

 

 

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