Saturday, November 22, 2014

Dorkbot SoCal 57 on Dec. 7

Dorkbot SoCal 57

***** Sunday, December 7, 2014
***** 12:00 noon to 2:00pm
***** Machine Project
***** 1200 D North Alvarado Street
***** Los Angeles, CA 90026
***** Google map of Machine Project

Speakers will include...

Brian Goeltzenleuchter

Scenting the antiseptic institution For over eight years Brian Goeltzenleuchter has designed olfactory-based art installations which disseminate scent in one of the most antiseptic of institutions, the art museum. While designing evocative smells might appear to be the olfactory artist's primary creative challenge, Brian's presentation will point to another challenge that is often overlooked for its technical and creative potential: The device itself used to transmit the scent. Using as case studies four recent art projects, Brian's Dorkbot presentation will consider a variety of scent distribution devices - from lower tech to higher tech - and offer technical, poetic and conceptual justification for his choice of each. The presentation will conclude with a description of a forthcoming project, and a challenge to the audience to identify solutions to the challenges it poses in distributing scent. 


Soyoung Shin

Soyoung lives in Los Angeles, California, USA. She graduated in 2011 from the University of Washington with a Bachelors of Science in Computer Science. She has a post-disciplinary practice that includes sculpture, performance, video, photography, and technology. Soyoung enjoys the intersection of media and science, and her work uses new technologies to create connections between viewers and ideas. Using found advertisements and a readymade discount robotic teddy bear, "THE 50% OFF BALLET" calls attention toward underlying attitudes which frame Valentine's Day. This piece places the viewer in a position where they are provided messaging from media ranging from musical typical of the holiday, to what could be considered perverse. 


Brian Matthews

Since engineer/artist Brian Matthews made his first pair of mechanical wings in 1998, wing making became his passion. He has made 17 pairs of wings varying in materials and operation from simple pulley opening to pneumatics and robotic control. Most recently, he built a robotic "extra hand", and a 3D printed robotic parrot called "Pollymer". 


Adam Florin

Adam will present a software system for creating generative music called Loom. Loom produces music by using random number generation to distort its internal model of musical "gesture". The project came out of his research and practice at CalArts.


Wednesday, November 12, 2014

Receiving Multicast on Ubuntu 12.04.4 LTS

If you are running Ubuntu 12.04.4 LTS, you may be surprised that you cannot receive multicast packets in your programs using the normal socket interface, but then you run tcpdump and can receive the multicast packets just fine.  You also might be surprised that you can send multicast packets just fine from your programs, but cannot receive them.

It turns out that you need to do this (as root):

echo 2 > /proc/sys/net/ipv4/conf/eth0/rp_filter

On every interface you wish to receive multicast packets on.

If you want the changes to rp_filter to be permanent, you need to add the changes to /etc/sysctl.conf and you may also want to tweak /etc/sysctl.d/10-network-security.conf

A great way to test the reception of multicast packets is "mcfirst", part of the ssmping package ("apt-get install sampling" to install).  mcfirst will let you listen to any group,port on any network interface.

"netstat -gn" will show you which multicast groups your network interfaces are subscribed to.

Tuesday, November 04, 2014

Open vSwitch on Ubuntu

OMG, don't try to build Open vSwitch from source if you can avoid it, if you are on Ubuntu just follow these steps to apt-get it, and then it builds the database and runs itself.

The problem is that most normal people just want to run ovs in a VM with mininet, but I wanted to run it on a real bare-metal server with actual traffic.