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https://github.com/ModusCreateOrg/slow

slow down a Linux network device to lower speeds (T1, 3G, 28.8k modem, etc)
https://github.com/ModusCreateOrg/slow

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slow down a Linux network device to lower speeds (T1, 3G, 28.8k modem, etc)

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README 

        
slow

====



This bash script offers quick shortcuts to simulate slower network connections.  It is useful when you need to simulate a wireless network on a Linux network server, especially when you are using a virtual machine guest on your local machine or in the cloud.



    slow 3G                   # Slow network on default eth0 down to 3G wireless speeds

    slow reset                # Reset connection for default eth0 to normal

    slow vsat                 # Simulate satellite internet  with a high latency

    slow dsl -b 1mbps         # Simulate DSL with a slower speed than the default

    slow modem-56k -d eth1    # Simulate a 56k modem on the eth1 device. eth0 is unchanged.

    slow -b 100000 -l 100ms   # Simulate network with a 100k bandwidth and 100ms latency

    slow T1 -p 0.1%           # Simulate T1 line with 1 in 1000 packet loss

    slow T3 -c 0.1%           # Simulate T3 line with 1 in 1000 packet corruption



If you assign more than one network interface to a virtual guest, you could run slow on one of the interfaces, so that it you can switch between fast and slow connections by switching the IP address endpoint.



Slow requires Linux and the 'tc' suite of traffic control tools.



See the [Cisco Global Cloud Index Supplement](http://www.cisco.com/c/en/us/solutions/collateral/service-provider/global-cloud-index-gci/CloudIndex_Supplement.html) for statistics on bandwidth and latency for countries all over the world.



Usage

=====



The available built-in targets simulate many common network scenarios. They start out

without assuming clear transmissions without extra delays, corruptions, or duplications.



Target                  | Description

------------------------|-------------------------------------------------

AMPS                    | 1G cell phone data

EDGE / 2.5G / GPRS          | 2G cell phone data

3G                      | 3G cell phone data

4G                      | 4G cell phone data

modem-0.1k / modem-110    | 110 baud modem, circa 1970s

modem-0.3k/ modem-300    | 300 baud modem, circa 1970s

modem-1.2k / modem-1200   | 1200 baud modem, circa 1980s

modem-2.4k/ modem-2400   | 2400 baud modem, circa 1980s

modem-9.6k / modem-9600   | 9600 baud modem, circa 1980s

modem-14.4k / modem-14400 | 14.4k modem, circa 1990s

modem-28.8k / modem-28800 | 28.8k modem, circa 1990s

modem-56k / modem-56000   | 56k modem, circa 2000

56k                     | 56k leased line (low latency)

T1 / t1                   | T1 line (1500Mbps, low latency)

T3 / t3                   | T3 line (45Mbps, low latency)

DSL / dsl                 | Consumer DSL

cablemodem              | Consumer cable modem

wifi-a / wifi-g           | 45Mbps WIFI

wifi-b                  | 11Mbps WIFI

wifi-n                  | 150Mbps WIFI

vsat                    | 5Mbps, high latency satellite terminal



By adding extra command line parameters you can tweak the behavior of the

network interface further, adding precise bandwidth and latency tweaks, or

add packet loss or corruption.



Parameter          |  Description

-------------------|---------------------------------------------------

-h / --help       |  Get help. Default behavior if no parameters given.

-v / --version    |  Version info

-d / --device     |  Set device name

-b / --bandwidth  |  Bandwidth, use bytes, kbps, mbps

-l / --latency    |  Latency, in ms, e.g. "20ms"

-p / --packetloss |  Packet loss in percent, e.g. "0.3%"

-c / --corruption |  Corrupt random bits, in percent, e.g. "0.01%"

-q / --quiet      |  Make output quiet



Testing

=======

This project is set up with [Vagrant](http://www.vagrantup.com/) to make it convenient

to test, even if you are not running Linux as your host operating system. 



Install Vagrant and [Virtualbox](http://www.virtualbox.org/) and issue the command `vagrant up` and then you can experiment with the different commands, for example:



    vagrant up

    vagrant ssh 

    # wait for vagrant prompt 

    sudo /vagrant/slow 56k



Credits

=======

Richard Bullington-McGuire  wrote the script inspired by a UI suggestion from Mike Schwartz . [Tyler Knappe](https://github.com/knappe) and [Adrian Silva](https://github.com/skiold) helped clean up the script.



Stack Overflow and Superuser questions that helped:

* http://stackoverflow.com/questions/402377/using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options/7680682#7680682

* http://superuser.com/questions/147156/simulating-a-low-bandwidth-high-latency-network-connection-on-linux



An [Aptivate blog post](https://web.archive.org/web/20111129155657/http://blog.aptivate.org/2010/01/23/make-sure-your-apps-work-in-the-field) lent some inspiration, as did [this script](https://web.archive.org/web/20130928002236/http://atmail.com/kb/2009/throttling-bandwidth) for throttling bandwidth.



Future Development

==================



It would be nice to expand the options that this took more options, such as adjusting for random fluctuations in speed, packet reordering, and smarter packet dropping. Reading up on the [Linux Advanced Routing and Traffic Control HOWTO](http://www.lartc.org/lartc.html) should provide food for thought.