Free air conditioners software for linux

Air Traffic Controller project is an air traffic controller simulation.

Airtraffic is a game/simulator that puts you into an air traffic controllers hotseat. Planes come into your airspace from various directions and you have to guide them safely to their destinations. It uses Python, Corba, and GTK.

The Wonder Shaper is a very special network shaper script with a lot of features. Works on Linux 2.4 & higher.

Goals

I attempted to create the holy grail:

* Maintain low latency for interfactive traffic at all times.

This means that downloading or uploading files should not disturb SSH or even telnet. These are the most important things, even 200ms latency is sluggish to work over.

* Allow surfing at reasonable speeds while up or downloading

Even though http is bulk traffic, other traffic should not drown it out too much.

* Make sure uploads dont harm downloads, and the other way around

This is a much observed phenomenon where upstream traffic simply destroys download speed. It turns out that all this is possible, at the cost of a tiny bit of bandwidth. The reason that uploads, downloads and ssh hurt eachother is the presence of large queues in many domestic access devices like cable or DSL modems.

Why it doesnt work well by default

ISPs know that they are benchmarked solely on how fast people can download. Besides available bandwidth, download speed is influenced heavily by packet loss, which seriously hampers TCP/IP performance. Large queues can help prevent packetloss, and speed up downloads. So ISPs configure large queues.

These large queues however damage interactivity. A keystroke must first travel the upstream queue, which may be seconds (!) long and go to your remote host. It is then displayed, which leads to a packet coming back, which must then traverse the downstream queue, located at your ISP, before it appears on your screen.

This HOWTO teaches you how to mangle and process the queue in many ways, but sadly, not all queues are accessible to us. The queue over at the ISP is completely off-limits, whereas the upstream queue probably lives inside your cable modem or DSL device. You may or may not be able to configure it. Most probably not.

So, what next? As we cant control either of those queues, they must be eliminated, and moved to your Linux router. Luckily this is possible.

Limit upload speed somewhat

By limiting our upload speed to slightly less than the truly available rate, no queues are built up in our modem. The queue is now moved to Linux.

Limit download speed

This is slightly trickier as we cant really influence how fast the internet ships us data. We can however drop packets that are coming in too fast, which causes TCP/IP to slow down to just the rate we want. Because we dont want to drop traffic unnecessarily, we configure a burst size we allow at higher speed.

Now, once we have done this, we have eliminated the downstream queue totally (except for short bursts), and gain the ability to manage the upstream queue with all the power Linux offers.

Let interactive traffic skip the queue

What remains to be done is to make sure interactive traffic jumps to the front of the upstream queue. To make sure that uploads dont hurt downloads, we also move ACK packets to the front of the queue. This is what normally causes the huge slowdown observed when generating bulk traffic both ways. The ACKnowledgements for downstream traffic must compete with upstream traffic, and get delayed in the process.

We also move other small packets to the front of the queue - this helps operating systems which do not set TOS bits, like everything from Microsoft.

Allow the user to specify low priority traffic (new in 1.1!)

Sometimes you may notice low priority OUTGOING traffic slowing down important traffic. In that case, the following options may help you:

NOPRIOHOSTSRC
Set this to hosts or netmasks in your network that should have low priority

NOPRIOHOSTDST
Set this to hosts or netmasks on the internet that should have low priority

NOPRIOPORTSRC
Set this to source ports that should have low priority. If you have an unimportant webserver on your traffic, set this to 80

NOPRIOPORTDST
Set this to destination ports that should have low priority.

See the start of wshaper and wshaper.htb

Results

If we do all this we get the following measurements using an excellent ADSL connection from xs4all in the Netherlands:

Baseline latency:
round-trip min/avg/max = 14.4/17.1/21.7 ms

Without traffic conditioner, while downloading:
round-trip min/avg/max = 560.9/573.6/586.4 ms

Without traffic conditioner, while uploading:
round-trip min/avg/max = 2041.4/2332.1/2427.6 ms

With conditioner, during 220kbit/s upload:
round-trip min/avg/max = 15.7/51.8/79.9 ms

With conditioner, during 850kbit/s download:
round-trip min/avg/max = 20.4/46.9/74.0 ms

When uploading, downloads proceed at ~80% of the available speed. Uploads at around 90%. Latency then jumps to 850 ms, still figuring out why.

What you can expect from this script depends a lot on your actual uplink speed. When uploading at full speed, there will always be a single packet ahead of your keystroke. That is the lower limit to the latency you can achieve - divide your MTU by your upstream speed to calculate. Typical values will be somewhat higher than that. Lower your MTU for better effects!

A small table:

Uplink speed | Expected latency due to upload
--------------------------------------------------
32 | 234ms
64 | 117ms
128 | 58ms
256 | 29ms

So to calculate your effective latency, take a baseline measurement (ping on an unloaded link), and look up the number in the table, and add it. That is about the best you can expect. This number comes from a calculation that assumes that your upstream keystroke will have at most half a full sized packet ahead of it.

This boils down to:

mtu * 0.5 * 10
-------------- + baseline_latency
kbit

The factor 10 is not quite correct but works well in practice.

Your kernel

If you run a recent distribution, everything should be ok. You need 2.4 with QoS options turned on.

If you compile your own kernel, it must have some options enabled. Most notably, in the Networking Options menu, QoS and/or Fair Queueing, turn at least CBQ, PRIO, SFQ, Ingress, Traffic Policing, QoS support, Rate Estimator, QoS classifier, U32 classifier, fwmark classifier.

In practice, I (and most distributions) just turn on everything.

The scripts

The script comes in two versions, one which works on standard kernels and is implemented using CBQ. The other one uses the excellent HTB qdisc which is not in the default kernel. The CBQ version is more tested than the HTB one!

See wshaper and wshaper.htb.

Tuning

These scripts need to know the real rate of your ISP connection. This is hard to determine upfront as different ISPs use different kinds of bits it appears. People report success using the following technique:

Estimate both your upstream and downstream at half the rate your ISP specifies. Now verify if the script is functioning - check interactivity while uploading and while downloading. This should deliver the latency as calculated above. If not, check if the script executed without errors.

Now slowly increase the upstream & downstream numbers in the script until the latency comes back. This way you can find optimum values for your connection. If you are happy, please report to me so I can make a list of numbers that work well. Please let me know which ISP you use and the name of your subscription, and its reputed specifications, so I can list you here and save others the trouble.

Installation

If you dial in, you can copy the script to /etc/ppp/ip-up.d and it will be run at each connect.

If you want to remove the shaper from an interface, run wshaper stop. To see status information, run wshaper status.

KNOWN PROBLEMS

If you get errors, add an -x to the first line, as follows:

#!/bin/bash -x

And retry. This will show you which line gives an error. Before contacting me, make sure that you are running a recent version of iproute!

Recent versions can be found at your Linux distributor, or if you prefer compiling, here:
ftp://ftp.inr.ac.ru/ip-routing/iproute2-current.tar.gz

Search And Rescue project is an air rescue flight simulator. The player pilots rescue helicopters to rescue victims in various situations of distress.

Search and Rescue is a helicopter based air rescue flight simulator. It employs a simple flight dynamics engine that is targetted towards the "average" player. It is not designed to be a cutting-edge realistic simulator, but rather a flexable game that everyone can play and enjoy.

The history of the development of this game goes back to 1997, when Search and Rescue was created as an explorative to design for more complex 3D games using the OpenGL graphics library. Much of the effort in the development of this game came from Wolfpack Entertainment and many dedicated contributors (see credits below).

This game was ported to Windows early on in its development to ensure the portability of its graphics code. However the Win32 version lacked certain features due to differences in Windows design of its graphic, sound, and controller implementation.

The flight dynamics engine (FDE) features helicopter, aircraft, and tilt-rotor aircraft flight dynamics models (FDMs). It uses source-centered (as opposed to world-centered) mathimatical equations to simulate movement which mimicks but does not fundimentally follow standard physics equations. This simplifies the "flyability" of the aircrafts at a slight cost of realisim and lightens processor load.

The 3D visual models of the aircrafts and objects were created by a program called Vertex 3D, an OpenGL modeller designed to create 3D visual models that are optimized for OpenGL.

Each scene is a finite sized flat world, separated vertically by cloud layer(s) and centered at the origin with an artificial longitude and latitude offset applied to displayed positions.

PircBot is a Java framework for writing IRC bots quickly and easily. PircBot has many features like an event-driven architecture to handle common IRC events, flood protection, DCC resuming support, ident support, and more. Its comprehensive logfile format is suitable for use with pisg to generate channel statistics. Full documentation is included, and this page contains a 5-minute step-by-step guide to making your first IRC bot.
PircBot allows you to perform a variety of fun tasks on IRC, but it is also used for more serious applications by the US Navy, the US Air Force, the CIA (unconfirmed), several national defence agencies, and inside the Azureus bittorrent client. But dont let that put you off - its still easy to use!
Enhancements:
- This release adds a new method to make it easy to identify with NickServ.
- This is useful on networks such as Freenode where a client must identify itself before it is able to send private messages.

Particle Simulation project is a simulation of spraying up to 60k particles in realtime.
Particle Simulation is a playful simulation game which allows you to spray particles into the "air". The number of simulated particles is only limited by the speed of your computer.
The particles dont interact with each other, but will bounce back from the ground and accelerate depending on a gravity constant.
This constant can be changed (along with a number of other parameters) in the source code or via commandline parameters.
Enhancements:
- Colors were adjusted and a new animation mode was introduced.
- Segmentation fault was fixed.

episoder is a tool to tell you when new episodes of your favourite TV shows are airing. episoder does so by parsing online TV show episode guides.
Currently episoder can parse the tv.com website thus it tells you whenever a new episode of a show listed on tv.com is aired.
Enhancements:
- Some parsing issues for certain shows were fixed.

CarWorld is a small driving simulator/demo I use to test various things of interest. It was mostly developed when I was a student. Car World is released with the full source code under the GNU General Public License.

The rendering

The two top pictures represent an slightly older version (v0.072) but graphically similar of CarWorld as it was presented for my project. v0.072 includes an OpenGL based renderer allowing
file input and displaying of texture mapped models with interpolated surface normals, real time projected shadows (as seen in the dino lights example).
background object
on screen command line to modify visual and simulation parameters

The mechanics

based on classical mechanics
uses standard metrics (Newtons, meters, seconds...)
there are no constraints on the environment surface
variable length time increments and variable increment number means "CarWorld time" is not dependent on frame rate.
adjustable simulation specs include: metrics, mass, moment of inertia around rotation axis, suspension pre load, compression damping, rebound damping, engine torque output, air friction, surface friction.

The Asterisk@Home Linux Distribution project enables the home user to quickly set up a VOIP Asterisk PBX. A web GUI makes configuration and operation easy. We also provide an xPL (home automation) interface for easy interaction with other devices in the home.
Main features:
- Asterisk 1.0.9
- Flash Operator Panel 0.21
- Festival Speech Engine version 1.95
- weather agi scripts
- wakeup calls
- Integrated WebMeetMe GUI
- AMP-1.10.008
- CentOS 3.5
- SugarCRM with Cisco XML Services interface + Click to Dial
- Music On Hold (mpg123)
- Fax support (spanDSP)
- xPL support
- Digium card auto-config
AMP (Asterisk Management Portal)
- AMP is a web GUI that allows the configuration of Asterisk without the need for editing config files. If you use AMP be careful not to make manual changes to the config files that will affect AMP?s operation.
Flash Operator Panel
- Flash Operator Panel is a real-time web interface to Asterisk. You can see what all of your extensions, trunks, and conferences are doing. We have extension 200 set up for testing. This is a live extension and will work as soon as a phone is registered to ext 200. The rest of the buttons are dummy objects for examples.
- The op_buttons.conf file has all of the configs for each button in Flash Operator Panel you can edit this using the Config Edit button on the maint menu. You must reboot the Asterisk or restart the panel service after you make changes. The normal config files for Flash Operator Panel end in .cfg we changed them to .conf so they would match the other Asterisk files.
Cisco XML Services
- Asterisk@Home has a Cisco XML Services that can be used to look up contacts in a database. Click on Web Address Book from the Asterisk@Home main menu. (user: admin password: password) and enter all of your contacts and their phone numbers.
Music On Hold (mpg123)
- Asterisk@Home has now uses mpg123 for music on hold. Put a call on hold and they hear music not dead air!
Fax support (SpanDSP)
- SpanDSP allows Asterisk to receive faxes. You can set this up in AMP.