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Using AWS MFA without a mobile phone

kinow @ Feb 28, 2017 00:47:03 ()

If you use AWS, the chances are that you use MFA - Multi-factor Authentication - to authenticate. I don’t like to install apps in my mobile phone, unless I need to, so having bought a new phone recently, I decided to find a replacement for Google Authenticator.

There are several command line utilities, browser extensions, libraries, and tools (free and paid) that implement the TOTP - time-based one-time password -, the standard required by Amazon for MFA authentication.

I decided to use a Go tool for the first time: gauth. Note that you won’t be able to use it from home, in case you don’t bring your laptop home. You can have one MFA device linked to your AWS account, so you may have to remove an existing one. Follow these instructions with care :^)

Install Go

sudo apt update && sudo apt upgrade -y
cd tmp/ && wget https://storage.googleapis.com/golang/go1.8.linux-amd64.tar.gz
tar -zxvf go1.*.tar.gz
sudo mv go /usr/local
vim ~/.bashrc

Add the following at the bottom of the file.

GOROOT=/usr/local/go
GOPATH="$HOME/go"
PATH="$GOPATH/bin:$GOROOT/bin:$PATH"

And you can test it with . ~/.bashrc && go version.

Install gauth

Given your environment is correctly set up, you should be able to use the following command to install gauth, and have it available in your $PATH.

go get github.com/pcarrier/gauth

Edit ~/.config/gauth.csv adding a value for the AWS MFA key.

Getting the AWS MFA key

To get the value that you must place in your gauth.csv file, you must add a new MFA device. When asked to scan a QR code, look for an option to enter the manual value. That will give you a long string. That’s the value you are looking for.

Extra: Auto copy-paste from command line

If you would like to quickly copy and paste, try creating an alias as described on this gist.

I used these instructions, and can now run one command line, that will put the next MFA code in my clipboard. Then just paste into my browser, and that’s that!

Happy hacking!

References

Proposed logos for OpenNLP

kinow @ Jan 15, 2017 20:42:03 ()

A couple of logos submitted to OPENNLP-6. Made with Inkscape, fonts from Google Fonts.

Proposed logos for OpenNLP
Proposed logos for OpenNLP

For more, check out my DeviantArt page.

Drawing Cave

kinow @ Jan 13, 2017 02:11:03 ()
Cave
Cave

Apache Commons Lang: Memoizer

kinow @ Jan 08, 2017 18:34:03 ()

The current release of Apache Commons Lang is 3.5. The upcoming release, probably 3.6, will include a new feature, added in a pull request: a Memoizer implementation. Check out the ticket LANG-740 for more about the implementation being added to [lang].

The book Java Concurrency in Practice introduces readers to the Memoizer, and has also a public domain implementation available for download (besides that, the book has also lots of other interesting topics!).

In summary, Memoizer is a simple cache, that will store the result of a computation. It receives a Computable object, responsible for doing something that will be stored by the Memoizer. Here’s a simple code to illustrate how that will work in your Java code.

// Computation to be stored in the cache
Computable<String, String> getFormattedCurrentDate = new Computable<String, String>() {
    @Override
    public String compute(String fmt) throws InterruptedException {
        return new SimpleDateFormat(fmt).format(new Date());
    }
};

// Our memoizer
Memoizer<String, String> dateCache = new Memoizer<>(getFormattedCurrentDate);

// To illustrate its use
for (int i = 0; i < 10; i++) {
    try {
        // S -> Millisecond
        System.out.println(dateCache.compute("HH:mm:ss:S Z dd/MM/YYYY"));
        // Regardless of this sleep call, we get the same result every iteration
        Thread.sleep(1500);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

The computable created (getFormattedCurrentDate) will be called only once, and stored in a map. The parameter passed in the #compute() method will be used as key in the map. So choose your parameter wisely :-) The output of the example will be similar to the following one.

19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017
19:15:57:854 +1300 08/01/2017

In the example above I used a for-loop to illustrate what will happen. Even though we call the memoizer #compute() method several times, followed by Thread#sleep(); only one result, the first to be computed, will be returned.

So that’s all for today. Hope you learned something about this new class, that must be available in the next release of Apache Commons Lang.

Happy hacking!

ps: [lang] uses Java 7, so that is why we do not have a functional instead of the Comparable

Apache Commons Text

kinow @ Jan 07, 2017 20:39:03 ()

There is a new component in Apache Commons: Apache Commons Text. The 1.0 release might be announced in the next weeks. The current site is still in the Commons Sandbox, but it will change with the 1.0 release. The promotion from the sandbox happened a few days ago in the project mailing list.

Here’s the project description: Apache Commons Text is a library focused on algorithms working on strings.

There was a thread on the mailing list some time ago (Oct/2014) when we first discussed the component idea. Since then many people contributed porting code from Apache Commons Lang, Apache Lucene, donating code from existing projects, and with new ideas.

It is important to be aware that certain parts of Apache Commons Lang are being marked as deprecated, and will be removed in the future, after Apache Commons Text 1.0 is out. For example: StringUtils, and RandomStringUtils.

That will happen probably in a 4.x release of Apache Commons Lang, if everything goes well with Apache Commons Text :-)

And there are already future features in branches too. It was decided that these features needed further work, so they will probably be included in next releases.

So that’s a little bit of background on the new component that will be released soon. If you have code using Apache Commons Lang, you might be interested in staying tuned to release announcements in the mailing list!

And should you have suggestions and would like to contribute, feel free to join and start a thread in the mailing list, open a JIRA issue, or submit a pull request.

Happy hacking!