Water Dog View

From today's ride.

Nice Snow

At Diamond today.

CentOS Development

I'm doing a lot of development on CentOS lately.

I've found that many things will fail because development packages are missing. For instance, this gem install fails:

sudo gem install curb
Building native extensions. This could take a while...
ERROR: Error installing curb:
ERROR: Failed to build gem native extension.

/usr/local/bin/ruby extconf.rb install curb
checking for main() in -lcurl... no
*** extconf.rb failed ***

This can often be fixed by installing the devel version of whatever you need. In this case you can see that the -lcurl is missing. So you fix it like this:

sudo yum install curl-devel

Now the gem install will work:

sudo gem install curb
Building native extensions. This could take a while...
Successfully installed curb-0.1.4
1 gem installed
Installing ri documentation for curb-0.1.4...
Installing RDoc documentation for curb-0.1.4...

So keep an eye out for those foo-devel packages. You'll need a lot of them.

More Close Obama Picks

Ok, this is getting weird. It seems Obama's choice to lead the FCC is Julius Genachowski, who was also an adviser to Truveo. As previously mentioned, I seem to know a lot of folks that are close to Obama. Obviously, I think Genachowski is a good guy.

Foggy Oracle

The fog was thick this morning. You can just see the Oracle towers
poking through.

Started Playing with OpenCV

I started playing around with OpenCV, the Open Computer Vision library today. I'm hoping to be able to derive interesting images from my web cameras. The above image is simply the result of running the hello-world.cpp program over the image from an earlier blog post.

It's pretty easy to install on the mac:

% sudo port install opencv

And then to compile:

% g++ `pkg-config --cflags --libs opencv` -o hello-world hello-world.cpp

And then to run:

% ./hello-world test.jpg

It pops up a window showing the inverted image and waits for a keypress before cleaning up.

Broken Port Forwarding

I've spent over an hour trying to get my new D-Link DCS-910 working from outside my home network. I've done this kind of thing a hundred times, basically I'm setting up port forwarding so incoming connections to my home router will get forwarded to my camera.

I was forwarding port 8085 to 10.1.1.205:8085 but it just wasn't working. Inside my network I was able to go to 10.1.1.205:8085 but I wasn't able to get to foo.mine.nu:8085 (where foo.mine.nu resolves to my home network courtsey of DynDNS). After trying lots of different ports and even reloading the firmware on my Netgear WPN824, it turns out it was something simple and had nothing to do with the Netgear. The problem was the default gateway setting on the D-Link camera. I had setup the DCS-910 to use the static IP address of 10.1.1.205. I didn't bother to set the default gateway. For some reason, this worked fine when I was going from some other machine on my 10.1.1.x network, but failed miserably when trying to connect from outside.

I don't disagree that leaving the default gateway set to 0.0.0.0 is a problem, I'm just suprised that the camera would work on my LAN but fail when accessed via port forwarding.

If you have a similar problem with port forwarding, make sure the device you're forwarding to has its default gateway properly set! Lesson learned.

Disclaimer: My camera really isn't at foo.mine.nu. I'm just using this FQDN as an example.