Fortunately, Bruce Schneier makes it very clear that it’s the latter, and that profiling is A Bad Idea™. Security in general (computer or otherwise), is often a more difficult problem than most people will admit. When you start to add politics, social norms, a need and desire for tolerance, good will, personal freedom and a revulsion of tyranny it becomes a more complex. I’m glad that Schneier is as good at getting his ideas across as Sam is – it would be a shame for the better idea to lose out because it’s not articulated as well as a bad one.

Despite this, I’m looking forward to hearing Sam’s counter argument. However, since I wasn’t convinced by his initial argument (and I find Bruce Schneier very convincing), I don’t expect he will change my mind on this.

As an aside: This is an example of what I really like about the skeptical/rational community. Sam was willing and did post a counter argument to his (one that was devestating to his postion in my view) on his own blog. Good ideas are allowed to win in an open dialogue.Veritas rex.

In this time, I did write a couple of blog posts for One-Time Secret. If you haven’t seen them, they’re here:

• A little blurb covering some frequently asked questions about Security, data protection and trust
• A minor rant and pet peeve of mine: ‘Good’ vs ‘Strong’ passwords
• Some helpful tips on Protecting your credentials from criminals

I’ve got a bunch of exciting new things on the horizon that I can’t announce yet, but will in the very near future.

]]> http://christopher.murtagh.name/2012/04/04/back-from-my-social-vacation/feed/ 0 http://christopher.murtagh.name/2011/12/12/simplerssembed-my-first-plugin/ http://christopher.murtagh.name/2011/12/12/simplerssembed-my-first-plugin/#comments Mon, 12 Dec 2011 09:49:41 +0000 cmurtagh http://christopher.murtagh.name/?p=137 Ok, I’ve been doing all sorts of things with WordPress for a while now, but oddly enough, I never actually wrote a plugin (although, in retrospect, I did a lot of template hacks that probably would have been easier to do as plugins). Anyway, I needed a plugin for a blog I was working on that would allow me to display the summary of N number of blog posts from another blog. There seem to be plenty of existing plugins that do this, however most of them are either horrible code (both HTML and PHP), or they don’t work with Atom feeds that don’t have descriptions. I wanted something very simple, with very clean output that would ‘just work’™. So, after trying about a dozen of them, I decided to just write my own (which turned out to be insanely easy). If I would have started down that path at first, I probably would have been done sooner.

So, if anyone is interested in this very simple plugin, here it is. Of course, it’s GPL. I expect I’ll be adding more features to it as I need, but for now this does exactly what I want with very little code to maintain.

Documentation

Download

You can get the current version from here: simplerssembed.zip

Installation

Put the contents of simpleressembed.zip into your wp-contents/plugins directory, and unzip it. This should give you a directory called ‘simpleressembed’ which has 3 things in it:

• an empty directory called ‘cache’
• a file called readme.txt
• a file called simplerssembed.php

Make sure that the cache directory is writeable by your web server, or whatever user that will be executing the php scripts. The safest way (on *nix system) is to do the following (assuming that the process runs as the user ‘apache’:

Then go to the plugins tool in your WP dashboard, and activate the plugin.

Using the plugin

Once the plugin is activated, you can embed RSS feeds with the following shortcode:

Parameters

The currently defined parameters are as follows:

Default values

The default values for the above parameters are:

Example output:

This is output from the actual code above:

Recently, I decided to upgrade the drives in my desktop. Since I don’t like the idea of downtime due to a failed drive (my desktop is also my home file server and firewall/router/dhcp server), I use software RAID1. The cost of an extra drive has been well worth the time saved from the last couple of HD failures I’ve had (including the lousy refurbished Seagate RMA drives). My initial array was 2 Seagate ST3750330AS (750GB, 32MB cache, 3Gb/s). They’re reasonably good drives, and I’ve had them for 4 years or so. For the same price I bought these drives for a couple of years ago, I managed to get 2 Western Digital WD1002FAEX-00Z3A0 (1TB, 64MB cache, 6Gb/s). So, a bit more space and faster drives. Now, the trick was to upgrade them without any downtime (other than the time to drives), or the need to resort to copying data off and/or restoring from backups (backups are important, but that’s another topic). In my setup, I have 2 drives (/dev/sda and /dev/sdb) which are combined to make 2 MD devices, /dev/md0 (my /boot partition, which is 100MB) and /dev/md1 (a physical volume used for LVM, and is the rest of the drive). Here are the steps I had to take to do this:

Step 1. Remove one drive from the array

Flag one of the drives as ‘faulty’ so that it can be removed from the array. In this case, I’m going to start with /dev/sda, but I could easily also use /dev/sdb. The command below will remove both partitions (sda1 and sda2) from their respected raid devices (md0 and md1) and set the drive as ‘failed’.

Step 2. Physically replace ‘failed’ drive

I then safely removed the ‘failed’ disk from my tower (kept is as a safety backup too), and replaced it with one of the 1TB drives.

Step 3. Copy partition data from old drive to new

I dumped the partition scheme from sda to sdb. This would have been more important if I was replacing the drive with an identical one (in the case of a drive failure). However, this would allow me to be sure that my md0 (/boot) partitions were the same size. IMPORTANT: Make sure you put the devices below in the right order, otherwise very, very bad things will happen.

If the above step looks too scary for you, then you might want to save the partition map to a file first, to at least have a chance of recovering it should you mess up. Here’s how:

Step 4. Replace 2nd partition with bigger one

Next I used fdisk to delete the 2nd partition so that it will be larger (almost 1TB instead of almost 750GB)

Now I’ve got 2 drives with 1 partition (for /boot) that is exactly the same size, and the second partition on the second drive is almost 1TB instead of 750GB. Software RAID is ok with this, and it will allow me to add both partitions to my previous RAID devices, however each device will only be the size of the smallest partition. I could have taken the opportunity to increase the size of md0 if I wanted to, but didn’t really need to.

Step 5. Update MBR for Grub

OK, this is going to assume you’re using grub as your bootloader and that it’s on the MBR. Since a drive has been replaced, this needs to updated otherwise the machine might not reboot.

Step 6. Add drive back to array

Next step is to add this drive back to the RAID array and rebuild.

Step 7. Wait, wait, wait

After that, I wait for the RAID to rebuild and show up in a 'clean' state. Since this is 750GB of data that needs to sync, it means several hours. So, I keep checking the state of the array until I see this: [root@mafalda ~]# mdadm --detail /dev/md1 /dev/md1: Version : 0.90 Creation Time : Fri Mar 14 23:36:49 2008 Raid Level : raid1 Array Size : 732467520 (698.54 GiB 750.05 GB) Used Dev Size : 732467520 (698.54 GiB 750.05 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Tue Nov 29 04:01:16 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 0 Spare Devices : 0 UUID : bad9d783:9b7b40be:9fd48ad3:7334f5c6 Events : 0.3555449

Step 8. Rince, lather and repeat

Repeat steps 1-7 using sdb instead of sda and vice versa.

Step 9. Resize the raid partition

After both drives have been replaced, the second RAID device is still only 750GB. It needs to be modified to bring it up to 1TB. This is the command to do that:

Checking the status of the device will show it's new size, and it's back to the waiting game.

Step 10. Resize the LVM physical volume

Now that the RAID device has been resized, the next step is to resize the LVM physical volume. The pvdisplay command confirms it:

Step 11. Adding adding the extra space to my /home partition

I've pretty much done all the necessary things that this post has set out to do. If I wanted to add 200GB of this data to say, my /home partition (the 'home_lv' logical volume in the 'mafalda_vg' volume group), this is what the commands would be:

[root@ ~]# lvresize -L +200G /dev/mapper/mafalda_vg-home_lv

Then I would need to grow the ext[2|3|4] filesystem, which can also be done online

That would effectively add 200GB to my /home partition. All done with minimal downtime (the time to swap physical drives).

I’ve often got things I’d like to share, or better still, discuss with other sysadmin friends, and Facebook doesn’t seem to do it for professional content, or for things that are worth keeping around – everything get lost in Facebook’s firehose way too quickly.

xzilla on #postgresql (irc.freenode.net) pointed me out to a recent blog posting of his that seemed to do what I wanted using Out parameters. This was really great, and I knew I had something I could work with there. Thanks xzilla!

So, I took it a bit further and modified his example slightly to see if I could also do it without the out parameters and just use the rowtype. Here’s the result:

CREATE TYPE footype AS (number int, oddoreven text);

CREATE OR REPLACE FUNCTION odd_or_even(int) RETURNS SETOF footype
AS $$
my @Return;
my $Count = 1;
my $Input = $_[0];

while ($Count <= 10) {
  if ($Input%2 == 0) {
     push @Return, { number => $Input, oddoreven => 'even' }
  } else {
     push @Return, { number => $Input, oddoreven => 'odd' }
  }
 $Count++;
 $Input++;
}

 foreach my $Row (@Return) {
     return_next $Row;
 }
 return;

$$ LANGUAGE plperl;

test=# SELECT * FROM odd_or_even(23)
test=# ORDER BY odd_or_even.oddoreven;
 number | oddoreven
--------+-----------
     24 | even
     26 | even
     28 | even
     30 | even
     32 | even
     23 | odd
     25 | odd
     27 | odd
     29 | odd
     31 | odd
(10 rows)