c0d3 :: j0rg3

A collection of tips, tricks and snips. A proud Blosxom weblog. All code. No cruft.

Tue, 18 Mar 2014

Random datums with Random.org

I was reading about the vulnerability in the ‘random’ number generator in iOS 7 (http://threatpost.com/weak-random-number-generator-threatens-ios-7-kernel-exploit-mitigations/104757) and thought I would share a method that I’ve used. Though, I certainly was not on any version of iOS but, at least, I can help in GNU/Linux and BSDs.

What if we want to get some random numbers or strings? We need a salt or something and, in the interest of best practices, we’re trying to restrain the trust given to any single participant in the chain. That is, we do not want to generate the random data from the server that we are on. Let’s make it somewhere else!

YEAH! I know, right? Where to get a random data can be a headache-inducing challenge. Alas! The noble people at Random.org are using atmospheric noise to provide randomness for us regular folk!

Let’s head over and ask for some randomness:
https://www.random.org/strings/?num=1&len=16&digits=on&loweralpha=on&unique=on&format=html&rnd=new

Great! Still feels a little plain. What if big brother saw the string coming over and knew what I was doing? I mean, aside from the fact that I could easily wrap the string with other data of my choosing.

Random.org is really generous with the random data, so why don’t we take advantage of that? Instead of asking for a single string, let’s ask for several. Nobunny will know which one I picked, except for me!

We’ll do that by increasing the 'num' part of the request that we’re sending:
https://www.random.org/strings/?num=25&len=16&digits=on&loweralpha=on&unique=on&format=html&rnd=new

They were also thinking of CLI geeks like us with the 'format' variable. We set that to 'plain' and all the fancy formatting for human eyes is dropped and we get a simple list that we don’t need to use any clever tricks to parse!
curl -s 'https://www.random.org/strings/?num=25&len=16&digits=on&loweralpha=on&unique=on&format=plain&rnd=new'

Now we’ve got 25 strings at the CLI. We can pick one to copy and paste. But what if we don’t want to do the picking? Well, we can use the local system to do that. We’ll have it pick a number between 1 and 25. It’s zero-indexed, so we’re going to increment by 1 so that our number is really between 1 and 25.
echo $(( (RANDOM % 25)+1 ))

Next, we’ll send our list to head with our random number. Head is going to give us the first X lines of what we send to it. So if our random number is 17, then it will give us the first 17 lines from Random.org
curl -s 'https://www.random.org/strings/?num=25&len=16&digits=on&loweralpha=on&unique=on&format=plain&rnd=new' | head -$(( (RANDOM % 25)+1 ))

After that, we’ll use the friend of head: tail. We’ll tell tail that we want only the last record of the list, of psuedo-random length, of strings that are random.
curl -s 'https://www.random.org/strings/?num=25&len=16&digits=on&loweralpha=on&unique=on&format=plain&rnd=new' | head -$(( (RANDOM % 25)+1 )) | tail -1

And we can walk away feeling pretty good about having gotten some properly random data for our needs!


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Permalink: 20140318.random.data

Mon, 17 Feb 2014

Installing INN’s Project Largo in a Docker containter

Prereqruisites: Docker, Git, SSHFS.

Today we’re going to look at using Docker to create a WordPress installation with the Project Largo parent theme and a child theme stub for us to play with.

Hart Hoover has established an image for getting a WordPress installation up and running using Docker. For whatever reason, it didn’t work for me out-of-box but we’re going to use his work to get started.

Let’s make a place to work and move into that directory:
cd ~
mkdir project.largo.wordpress.docker
cd project.largo.wordpress.docker

We’ll clone the Docker/Wordpress project. For me, it couldn’t untar the latest WordPress. So we’ll download it outside the container, untar it and modify the Dockerfile to simply pull in a copy:
git clone https://github.com/hhoover/docker-wordpress.git
cd docker-wordpress/
ME=$(whoami)
wget http://wordpress.org/latest.tar.gz
tar xvf latest.tar.gz
sed -i 's/ADD http:\/\/wordpress.org\/latest.tar.gz \/wordpress.tar.gz/ADD \.\/wordpress \/wordpress/' Dockerfile
sed -i '/RUN tar xvzf \/wordpress\.tar\.gz/d' Dockerfile

Then, build the project which may take some time.
sudo docker build -t $ME/wordpress .

If you’ve not the images ready for Docker, the process should begin with something like:
Step 0 : FROM boxcar/raring
Pulling repository boxcar/raring
32737f8072d0: Downloading [> ] 2.228 MB/149.7 MB 12m29s

And end something like:
Step 20 : CMD ["/bin/bash", "/start.sh"]
---> Running in db53e215e2fc
---> 3f3f6489c700
Successfully built 3f3f6489c700

Once the project is built, we will start it and forward ports from the container to the host system, so that the Docker container’s site can be accessed through port 8000 of the host system. So, if you want to see it from the computer that you’ve installed it on, you could go to ‘HTTP://127.0.0.1:8000’. Alternatively, if your host system is already running a webserver, we could use SSHFS to mount the container’s files within the web-space of the host system.

In this example, however, we’ll just forward the ports and mount the project locally (using SSHFS) so we can easily edit the files perhaps using a graphical IDE such as NetBeans or Eclipse.

Okay, time to start our Docker image and find its IP address (so we can mount its files):
DID=$(docker run -p 8000:80 -d $ME/wordpress)
DIP=$(docker inspect $DID | grep IPAddress | cut -d '"' -f 4)
docker logs $DID| grep 'ssh user password:' --color

Copy the SSH password and we will make a local directory to access the WordPress installation of our containter.
cd ~
mkdir largo.mount.from.docker.container
sshfs user@$DIP:/var/www $HOME/largo.mount.from.docker.container
cd largo.mount.from.docker.container
PROJECT=$(pwd -P)

Now, we can visit the WordPress installation and finish setting up. From the host machine, it should be ‘HTTP://127.0.0.1:8000’. There you can configure Title, Username, Password, et cet. and finish installing WordPress.

Now, let’s get us some Largo! Since this is a test project, we’ll sacrifice security to make things easy. Our Docker WordPress site isn’t ready for us to easily install the Largo parent theme, so we’ll make the web directory writable by everybody. Generally, this is not a practice I would condone. It’s okay while we’re experimenting but permissions are very important on live systems!

Lastly, we’ll download and install Largo and the Largo child theme stub.
ssh user@$DIP 'sudo chmod -R 777 /var/www'
wget https://github.com/INN/Largo/archive/master.zip -O $PROJECT/wp-content/themes/largo.zip
unzip $PROJECT/wp-content/themes/largo.zip -d $PROJECT/wp-content/themes/
mv $PROJECT/wp-content/themes/Largo-master $PROJECT/wp-content/themes/largo
wget http://largoproject.wpengine.netdna-cdn.com/wp-content/uploads/2012/08/largo-child.zip -O $PROJECT/wp-content/themes/largo-child.zip
unzip $PROJECT/wp-content/themes/largo-child.zip -d $PROJECT/wp-content/themes
rm -rf $PROJECT/wp-content/themes/__MACOSX/

We are now ready to customize our Project Largo child theme!


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Permalink: 20140217.project.largo.docker

Wed, 15 May 2013

Git: an untracked mess?

There may be times when you find your Git repository burdened with scads of untracked files left aside while twiddling, testing bug patches, or what-have-youse.

For the especially scatter-brained among us, these things can go unchecked until a day when the useful bits of a git status scroll off the screen due to utterly unimportant stuff. Well, hopefully unimportant.

But we’d better not just cleave away everything that we haven’t checked in. You wonder:
What if there’s something important in one of those files?

You are so right!

Let’s fix this!

Firstly, we want a solution that’s reproducible. Only want to invent this wheel once, right?

Let’s begin with the play-by-play:

Git, we want a list of what isn’t tracked: git ls-files -o --exclude-standard -z

We’ll back these files up in our home directory (~), using CPIO but we don’t want a poorly-named directory or finding anything will become its own obstacle. So we’ll take use the current date (date +%Y-%m-%d), directory (pwd) and branch we’re using (git branch) and we’ll twist all of it into a meaningful, but appropriate, directory name using sed. git ls-files -o --exclude-standard -z | cpio -pmdu ~/untracked-git-backup-`date +%Y-%m-%d`.`pwd | sed 's,^\(.*/\)\?\([^/]*\),\2,'`.`git branch | grep "*" | sed "s/* //"`/

Then Tell Git to remove the untracked files and directories: git clean -d -f

Ahhhh… Much better. Is there anything left out? Perhaps. What if we decide that moving these files away was a mistake? The kind of mistake that breaks something. If we realize right away, it’s easily-enough undone. But what if we break something and don’t notice for a week or two? It’d probably be best if we had an automated script to put things back the way they were. Let’s do that.

Simple enough. We’ll just take the opposite commands and echo them into a script to be used in case of emergency.

Create the restore script (restore.sh), to excuse faulty memory: echo "(cd ~/untracked-git-backup-`date +%Y-%m-%d`.`pwd | sed 's,^\(.*/\)\?\([^/]*\),\2,'`.`git branch | grep "*" | sed "s/* //"`/; find . -type f \( ! -iname 'restore.sh' \) | cpio -pdm `pwd`)" > ~/untracked-git-backup-`date +%Y-%m-%d`.`pwd | sed 's,^\(.*/\)\?\([^/]*\),\2,'`.`git branch | grep "*" | sed "s/* //"`/restore.sh

Make the restore script executable: chmod u+x ~/untracked-git-backup-`date +%Y-%m-%d`.`pwd | sed 's,^\(.*/\)\?\([^/]*\),\2,'`.`git branch | grep "*" | sed "s/* //"`/restore.sh

Lastly, the magic, compressed into one line that will stop if any command does not report success: a='untracked-git-backup-'`date +%Y-%m-%d`.`pwd | sed 's,^\(.*/\)\?\([^/]*\),\2,'`.`git branch | grep "*" | sed "s/* //"`; git ls-files -o --exclude-standard -z | cpio -pmdu ~/$a/ && git clean -d -f && echo "(cd ~/$a/; find . -type f \( ! -iname 'restore.sh' \) | cpio -pdm `pwd`)" > ~/$a/restore.sh && chmod +x ~/$a/restore.sh; unset a


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