During frontend development, we have optimized network environment, network lagging isn't an issue for developer.
But once deployed, the site receives feedback from users who are suffering from network logging. They might not receive an timed AJAX response, they might be blocked by one large script/image loading, they might not load the required JS for the site to function.
I want to test our site with bad network condition, so the question is how could we imitate bad networking in our develop environment?
Use a BSD machine with dummynet. dummynet is awesome and exactly what you're looking for. You'll need a machine with two NIC's to "route" your traffic through running a BSD variant (FreeBSD, OS X).
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I am currently writing an app that is planned to control a machine. The machine is controlled by a Raspberry Pi, which offers an API (via flask) to the local wifi. The app on the other hand is also connected to the same wifi and accesses the API.
To make sure that not everybody who downloads the app and is connected to the wifi, can control the machine, I setup some basic authentication.
My next step was actually to switch to https with a self-signed certificate. But the machine(/the raspberry pi) and the app need to be in the same wifi to communicate. So there are actually no intermediaries in the communication. This again makes me wonder if there is any possibility of a man-in-the-middle-attack and if I really need https communication.
So my question is: do I need https here?
A subjective answer. First you have to decide what is the risk to your machine if someone/thing gets control of it. For most consumer applications, within the household maybe that risk is low (maybe not - what about an irrigation controller or heater?). Then why and with what probability would someone WANT to hack in (maybe if your machine is a best seller across the globe it might be a fun target).
You might be surprised at how many devices are on a normal households wifi - dozens at least. Furthermore - while most consumer devices don't rely on inbound access (most use a website to bounce control/commands through) there are probably a lot more inbound (from the internet) ports that have been opened through firewalls than you imagine.
So - I do think there are many opportunities for MITM in a normal household wifi. Whether that would be a concern in early product development - that's up to you.
This SO answer: Is it possible to prevent man-in-the-middle attack when using self-signed certificates? might be useful when actually implementing.
I'd like to set up a proxy between my home network and internet.
Currently computers at home connect to a cisco router which is connected to internet.
What I'd like is to set up system so that all internet traffic goes through a proxy - in my case it is a dedicated extra computer (server).
Are there programmable routers that can run some software within the router or using a connected computer?
This way I could use a program to see what goes out and comes in.
If you only want to monitor your network then investigate and learn how to use WireShark. If you want to take the long and much harder route of making a proxy server, use a squid proxy. It runs on a Linux server and you can get a lot of user friendly GUI's. Plus there are hundreds of tutorials.
I'm very new to network programming, and would appreciate some help understanding what some good progress steps would be. I am designing an iOS app that requires real-time information to be delivered over a network from another machine. I know the IP address of this machine, as well as the API that the machine adheres to in terms of sending and receiving messages.
From doing some research, it seems like I need to open up a socket on one of the machine's ports, and open up another socket on my computer, and then use TCP/IP to send and receive packets between the two.
What is a good overview of the process that I need to do at this point? Which languages and environments would you suggest that would be most efficient for me to be able to get the information I need from this machine into my XCode project?
Thanks! Any help would be appreciated.
you just need to look for examples of how to do "socket programming" for IOS. here's one resource:
http://www.tekritisoftware.com/sites/default/files/Socket_Programing_for_IOS.pdf
I'm looking into getting an openfire server started and setting up a strophe.js client to connect to it. My concern is that using http-bind might be costly in terms of performance versus making a straight on XMPP connection.
Can anyone tell me whether my concern is relevant or not? And if so, to what extend?
The alternative would be to use a flash proxy for all communication with OpenFire.
Thank you
BOSH is more verbose than normal XMPP, especially when idle. An idle BOSH connection might be about 2 HTTP requests per minute, while a normal connection can sit idle for hours or even days without sending a single packet (in theory, in practice you'll have pings and keepalives to combat NATs and broken firewalls).
But, the only real way to know is to benchmark. Depending on your use case, and what your clients are (will be) doing, the difference might be negligible, or not.
Basics:
Socket - zero overhead.
HTTP - requests even on IDLE session.
I doubt that you will have 1M users at once, but if you are aiming for it, then conection-less protocol like http will be much better, as I'm not sure that any OS can support that kind of connected socket volume.
Also, you can tie your OpenFires together, form a farm, and you'll have nice scalability there.
we used Openfire and BOSH with about 400 concurrent users in the same MUC Channel.
What we noticed is that Openfire leaks memory. We had about 1.5-2 GB of memory used and got constant out of memory exceptions.
Also the BOSH Implementation of Openfire is pretty bad. We switched then to punjab which was better but couldn't solve the openfire issue.
We're now using ejabberd with their built-in http-bind implementation and it scales pretty well. Load on the server having the ejabberd running is nearly 0.
At the moment we face the problem that our 5 webservers which we use to handle the chat load are sometimes overloaded at about 200 connected Users.
I'm trying to use websockets now but it seems that it doesn't work yet.
Maybe redirecting the http-bind not via Apache rewrite rule but directly on a loadbalancer/proxy would solve the issue but I couldn't find a way on how to do this atm.
Hope this helps.
I ended up using node.js and http://code.google.com/p/node-xmpp-bosh as I faced some difficulties to connect directly to Openfire via BOSH.
I have a production site running with node.js configured to proxy all BOSH requests and it works like a charm (around 50 concurrent users). The only downside so far: in the Openfire admin console you will not see the actual IP address of the connected clients, only the local server address will show up as Openfire get's the connection from the node.js server.
The Performance Golden Rule from Yahoo's performance best practices is:
80-90% of the end-user response time
is spent downloading all the
components in the page: images,
stylesheets, scripts, Flash, etc.
This means that when I'm developing on my local webserver it's hard to get an accurate idea of what the end user will experience.
How can I simulate latency so that I can understand how my application will perform when I've deployed it on the web?
I develop primarily on Windows, but I would be interested in solutions for other platforms as well.
A laser modem pointed at the mirrors on the moon should give latency that's out of this world.
Fiddler2 can do this very easily. Plus, it does so much more that is useful when doing development.
YSlow might help you out. YSlow analyzes web pages based on Yahoo!'s rules.
Firefox Throttle. This can throttle speed (Windows only).
These are plugins for Firefox.
You can just set up a proxy outside that will tunnel traffic from your web server to it and then back to local browser. It would be quite realistic (of course it depends where you put the proxy).
Otherwise you can find many ways to implement it in software..
Run the web server on a nearby Linux box and configure NetEm to add latency to packets leaving the appropriate interface.
If your web server cannot run under Linux, configure the Linux box as a router between your test client machine and your web server, then use NetEm anyway
While there are many ways to simulate latency, including some very good hardware solutions, one of the easiest for me is to run a TCP proxy in a remote location. The proxy listens and then directs the traffic back to my final destination. On a remote server, I run a unix program called balance. I then point this back to my local server.
If you need to simulate for a just a single server request, a simple way is to simply make the server sleep() for a second before returning.