Show HN: Crapify, a proxy for simulating slow, spotty HTTP connections

[BenjaminCoe]

https://www.npmjs.com/package/crapify

[semi-extrinsic]

Nice! There was a different tool in the same category, aptly named "Comcast", featured on HN a few weeks ago: https://github.com/tylertreat/Comcast

[tuananh → semi-extrinsic]

i thought u were being sarcastic but then you put the github's repo link there. LOL

[BenjaminCoe]

At work we've been running into problems performing npm installs over a VPN. I'm suspicious that it relates to executing too many concurrent HTTP requests. This motivated me to create crapify, a tool which lets us experiment with throttling connection speed and concurrency.

[taf2]

On OS X you can achieve something similar using ipfw

For example,

sudo ipfw pipe 1 config bw 500KByte/s

Limits all network on your box to 500kb/s

sudo ipfw add 1 pipe 1 src-port 443

To direct all traffic through port 443 through your slow pipe

sudo ipfw delete 1

When you are all done delete

[JonnieCache → taf2]

Don't the OSX devtools have a GUI for doing this? Can't remember what its called, I don't have XCode installed these days, but I remember it being pretty nifty.

EDIT: its called the Network Link Conditioner and apparently you install it from within xcode now.

EDIT2: I have just learned that ipfw is gone in yosemite? How distressing. Did they replace it with something?

[apinstein → JonnieCache]

I have Network Link Conditioner installed on my Yosemite Mac OS X box and it works fine (though it was installed prior to the Yose upgrade).

I learned about it here: http://nshipster.com/network-link-conditioner/

[tylertreat → JonnieCache]

I think pfctl is the suggested replacement for ipfw, which was deprecated in Mavericks. I wrote the Comcast tool someone linked in this thread. Haven't had a chance to dive through the pfctl man pages to add support for Yosemite yet unfortunately.

[taf2 → JonnieCache]

You are right http://apple.stackexchange.com/questions/24066/how-to-simula...

Is a good thread to follow

[imjared → taf2]

I (and folks I work with) have had really great success using Charles Proxy for per-machine bandwidth throttling.

Also has some handy features like AJAX debugging.

http://www.charlesproxy.com/overview/about-charles/

[james33 → taf2]

Unfortunately ipfw has been removed in Yosemite. Fortunately, there is something similar built into Chrome dev tools now.

[Spooky23]

This is cool. If it could add random NATing between various VLANs and occasionally not open firewall ports as configured, it would be a simulation of my work environment!

[hippich]

For linux there is tool 'tc'

[hrjet]

A more complete version of this: https://github.com/lightbody/browsermob-proxy

    * captures performance data in the HAR format.
    * blacklisting and whitelisting certain URL patterns
    * simulating various bandwidth and latency
    * remapping DNS lookups
    * flushing DNS caching
    * controlling DNS and request timeouts
    * automatic BASIC authorization
    * REST API

[qprofyeh]

If you simply need to test a website on a simulated slow connection, then Chrome Devtools. For all other purposes, this looks great!

[youngtaff]

Why not use DummyNet, Clumsy or Network Link Conditioner (depending on your OS of choice)?

If you really need a HTTP proxy there are tools like Charles (although the low RTT to a proxy may change the nature of the testing)

[BenjaminCoe → youngtaff]

My main use-case is programmatically throttling the outbound concurrent connections to a VPN. Writing a small proxy server in Node.js seemed like a reasonable approach for this.

[spacemanmatt → youngtaff]

Back in my network engineering days there were iptables rules to crapping up the packets. Was very useful for simulating dialup connections.