I am working on a small iOS application which has to download some files from a server using HTTP. In some cases, it is desirable to do this over another interface than the default (i.e., use 3G rather than Wifi).
Currently, I use the NSURLConnection (and the other NSURL-classes) to retrieve the files. However, I have not found a way to bind this connection to a specific interface/socket. I have successfully created active sockets for each interface (using the normal BSD socket-calls).
Is there any way to configure NSURLConnection to use these sockets, or another way to force it to use a specific network interface? Or is my only option to use CFNetwork (I want to do as little work as possible related to HTTP :))?
Check out the Reachability example, it can tell you if your target host is reachable via wwan, wifi or not at all.
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I need to make TCP based decentralised chat app for local network. By decentralised I mean there is no central server. Each entity on a network should have server/client architecture. When app starts it should check which user is online ( already running the app ). My question is how can i check that? Can i do it by trying to connect via connect() function from socket library? I'm new to programming, especially socket programing, so if it's a dumb question sorry in advance.
You should definitely study how other decentralized applications do this. There are lots of techniques.
Each instance of the application should, as part of its server functionality, track the addresses of other instances of the application. Each instance should, as part of its client functionality, keep track of a few instances it can connect to. Prefer instances that have been around for a long time.
The software should include a list of servers that have been running for a long time and are expected to typically be available. You may wish to include a fallback method such DNS, maintained by anyone willing to keep a list of well-known servers offering access through a well-known port. The fallback method can also be IRC or HTTP.
If you want to stay decentralized, you might want to try multicasting or broadcasting a request packet to all hosts on the network to discover other instances of your chat application.
Something similar has been implemented in Pidgin, named Bonjour. It works quite nicely and provides chatting capabilities on a local network. More specifically, it is defined as a Serverless Messaging part of XMPP.
If you are looking for code examples, have a look at one of my projects where I use multicast to discover hosts on the local network that provide a specific service: Headers and implementation.
I am implemneting a code based on Raw sockets. In order to receive coming Ethernet frames I have to bind the socket I created to an Ethernet interface. The only way to do that, as far as I am concerned, is via setsockopt() function with the option SO_BINDTODEVICE.
The problem is that I am using FreeBSD which does not support such option. Is there any patch to use in order to enable this feature or any other trusted alternative?
You can use sendto if you are working with IPv6, see this example.
Unfortunately this doesn't work with IPv4.
As antiduh said, you can use libpcap to capture packets, provided you have access to /dev/bpf (which is usually restricted to root).
I'm trying to implement an RTSP proxy server in order to analyse RTCP packets and dynamically switch to higher or lower bitrate streams (served by Wowza).
Can someone recommend an existing opensource proxy (Java) and a client that allows me to set the proxy? I've tried to use VLC for testing but apparently VLC does not allow me to set the RTSP proxy. What alternatives exist, do I need to create my own client?
If you can use .Net my implementation is full featured and contains not only a RtspClient but also a RtspServer so you can pass the changes in the source back down to the clients seamlessly.
https://net7mma.codeplex.com/
I am trying to build an application that can inform a user about website specific information whenever they are visiting a website that is present in my database. This must be done in a browser independent way so the user will always see the information when visiting a website (no matter what browser or other tool he or she is using to visit the website).
My first (partially successful) approach was by looking at the data packets using the System.Net.Sockets.Socket class etc. Unfortunately I discoverd that this approach only works when the user has administrator rights. And of course, that is not what I want. My goal is that the user can install one relatively simple program that can be used right away.
After this I went looking for alternatives and found a lot about WinPcap and some of it's .NET wrappers (did I tell you I am programming c# .NET already?). But with WinPcap I found out that this must be installed on the user's pc and there is nog way to just reference some dll files and code away. I already looked at including WinPcap as a prerequisite in my installer but that is also to cumbersome.
Well, long story short. I want to know in my application what website my user is visiting at the moment it is happening. I think it must be done by looking at the data packets of the network but can't find a good solution for this. My application is build in C# .NET (4.0).
You could use Fiddler to monitor Internet traffic.
It is
a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler includes a powerful event-based scripting subsystem, and can be extended using any .NET language.
It's scriptable and can be readily used from .NET.
One simple idea: Instead of monitoring the traffic directly, what about installing a browser extension that sends you the current url of the page. Then you can check if that url is in your database and optionally show the user a message using the browser extension.
This is how extensions like Invisible Hand work... It scans the current page and sends relevant data back to the server for processing. If it finds anything, it uses the browser extension framework to communicate those results back to the user. (Using an alert, or a bar across the top of the window, etc.)
for a good start, wireshark will do what you want.
you can specify a filter to isolate and view http streams.
best part is wireshark is open source, and built opon another program api, winpcap which is open source.
I'm guessing this is what you want.
capture network data off the wire
view the tcp traffic of a computer, isolate and save(in part or in hole) http data.
store information about the http connections
number 1 there is easy, you can google for a winpcap tutorial, or just use some of their sample programs to capture the data.
I recomend you study up on the pcap file format, everything with winpcap uses this basic format and its structers.
now you have to learn how to take a tcp stream and turn it into a solid data stream without curoption, or disorginized parts. (sorry for the spelling)
again, a very good example can be found in the wireshark source code.
then with your data stream, you can simple read the http format, and html data, or what ever your dealing with.
Hope that helps
If the user is cooperating, you could have them set their browser(s) to use a proxy service you provide. This would intercept all web traffic, do whatever you want with it (look up in your database, notify the user, etc), and then pass it on to the original location. Run the proxy on the local system, or on a remote system if that fits your case better.
If the user is not cooperating, or you don't want to make them change their browser settings, you could use one of the packet sniffing solutions, such as fiddler.
A simple stright forward way is to change the comupter DNS to point to your application.
this will cause all DNS traffic to pass though your app which can be sniffed and then redirected to the real DNS server.
it will also save you the hussel of filtering out emule/torrent traffic as it normally work with pure IP address (which also might be a problem as it can be circumvented by using IP address to browse).
-How to change windows DNS Servers
-DNS resolver
Another simple way is to configure (programmaticly) the browsers proxy to pass through your server this will make your life easier but will be more obvious to users.
How to create a simple proxy in C#?
I have an app that connects to an inhouse gameserver. I want to wrap the traffic in SSL to prevent hackers from sniffing the passwords and what not. Anyways, how do I go about doing that with an iphone app? I'm using CFNetwork to communicate to the server, and everything is in our own inhouse protocol instead of using http or something like that.
Thanks
You will need to set the appropriate CFStream properties prior to opening the streams. You do so by first preparing a dictionary using the appropriate kCFStreamSSL* keys and corresponding values and then calling CFWriteStreamSetProperty() to set that dictionary as the kCFStreamPropertySSLSettings property. The property should be shared between both streams in the connection pair.
If your server attempts to negotiate an SSL connection, I believe the streams will cooperate in the negotiation by default. You might have less work to do than you think.