Month: March 2017

Recommendation engine lock-in

Andrei KNo Comments

Youtube’s recommendation engine, at least in my experience, has three modes:
– Suggest the channels of which I’ve already watched the content:
– Suggest me the content I’ve already watched to watch again
– Suggest me the new updates on the playing lists of which I’ve already watched several videos

Unfortunately, while it works very well when I’ve just discovered a new couple of channels and have their content chosen and pushed to me, it fails to deliver the experience of discovery – it’s overfitting my late preferences, locking me in into the videos similar to what I have watched instead of suggesting me new content and new types of content I might be interested in. And seen that I also experience the same problem with the Quora’s recommendation engine (a couple of upvotes and all of my feed is almost exclusively army weapon tech).

I feel like the recommendation engine creators should abandon their blind faith into general algorithms and try to figure out how to create feeds that are interesting and engaging with respect to several categories of interest of their user, as well covering several reasons I might be seeking for a recommendation to what to watch (what is everyone else is watching – have something to discuss with my friends; discover something new; follow up on topics I am already interested in, …)

Synergy from the boot on Ubuntu

Andrei KNo Comments

This one seemed to be quite trivial per official blog, but the whole pipeline gets a bit more complicated once the SSL enters into the game. Here is how I made it work with synergy and Ubuntu 14.04

  • Configure the server and the client with the GUI application
  • Make sure SSL server certificate fingerprint was stored in the ~/.synergy/SSL/Fingerprints/TrustedServers.txt
  • Run sudo -su myself /usr/bin/synergyc -f --enable-crypto my.server.ip.address
  • After that check everything was working with sudo /usr/bin/synergyc -d DEBUG2 -f --enable-crypto my.server.ip.address
  • Finally add the greeter-setup-script=sudo /usr/bin/synergyc --enable-crypto my.server.ip.address line into the /etc/lightdm/lightdm.conf file under the [SeatDefaults] section

Why you shouldn’t do it?

Despite the convenience, there seemed to be a bit or an interference for the keyboard command and command interpretation on my side, so since my two computers side by side and since I have an usb button switch from before I got synergy, I’ve decided to manually start synergy every time I log in.

Linux server security

Andrei KNo Comments

DISCLAIMER: I AM NOT AN INFOSEC EXPERT. THIS ARTICLE IS MORE OF A MEMO FOR MYSELF. IF YOU LOOSE DATA OR HAVE A BREACH, I BEAR NO RESPONSIBILITY IN IT.

Now, because of all the occasions at which I had to act as a makeshift sysadmin, I did end up reading a number of policies and pick up some advice I wanted to group in a single place, if but for my own memory.

Installation:

  • Use SE Linux distro
  • Use an intrusion prevention tool, such as Fail2Ban
  • Configure primary and secondary DHS
  • Switch away from the password-protected SSH to a key-based SSH log-in. Diable root login all together (/etc/ssh/sshd_config, PermitRootLogin no). Here is an Ubuntu/OpenSSH guide.
  • Remove network super-service packages
  • Disable Telnet and FTP (SFTP should be used)
  • use chroot where available, notably for webservers and FTP servers
  • encrypt the filesystem
  • disable remote root login
  • disable sudo su – all the root actions need to be done with a sudo

Audit:

  • Once the server has been build, run Lynsis. It will audit your system and suggest additional steps to protect your machine
  • Force multi-factor authentification for the roots, especially via SSH. Here is a tutorial from Digital Ocean.

Watching the logs:

If you have more than one logging system to watch:

Configuring PyCharm for remote development

Andrei KNo Comments

I do most of my programming from my windows laptop and/or desktop computer. However, in order to be able to develop anything sane, I need to operate fully in Linux. I used to have to dualboot or even to have two machines, but now that I have access to a stable server I can safely ssh into, I would rather just use my IDE to develop directly on it. Lucky enough for me, PyCharm has an option for it.

A how-to guide to do this is pretty straightforward, well-explained on the PyCharm blog and docs explaining how to configure a remote server that is not a Vagrant box.

There are three steps in the configuration:

  • setting up the deployment server and auto-update
  • setting up the remote interpreter
  • setting up the run configuration

Setting up the deployment server:

Tools | Deployment | Configuration > configure your sftp server, go ahead and perform the root autodetection (usually the /home/uname) and uncheck the “available only for this project. You will need that last option in order to configure the remote interpreter. Go ahead, go into the mapping, perform the equivalence mappings for the project, but be aware the home from the previous screen, if filled, would be prepended to any path you try to map to on the remote server. So if you want your project to go to /home/uname/PycharmProjects/my_project and your root is /home/uname/, the path you are mapping to needs to be /PycharmProjects/my_projet.

Now, head to the Tools | Deployment click the automatic upload, so that every edit you do on your machine is constantly uploaded to the remote server.

Setting up the remote interpreter:

Head to the File | Settings | Project | Interpreter, click on the cogwheel and click on add remote. At that point by default PyCharm will fill in the properties for the “deployment configuration”. In my case I needed to tweak a bit the python interpreter path, since I use Anaconda Python (scientific computing). If like me you use Anaconda2 and store it in your home directory, you will need to replace the interpreter path by /home/uname/anaconda/bin/python. At that point, just click save and you are good for this part.

Setting up the run configuration:

With the previous two steps finished, when you go into Run | Edit configuration, add the main running script to the Script field, check that the python interpreter is configured to be the remote one and then click on the three small dots next to “path mappings” field and fill it out, at least with the location of the script on your machine mapped to it’s location on the remote.

That’s it, you are good to go!