For the past two week I have been unsuccessfully trying to implement udp hole punching, but I'm not sure why. I understand that the algorithm for hole punching is not guaranteed to work, but I believe it should work in my test case because I have noticed that once I bind my socket on my home-network, the port is the same to the outside world as it is locally, and stays that way for all connections made from this socket. Any help after reviewing my trials would be appreciated.
I have three computers, my osx desktop, my iPhone, and my amazon ec2 ami.
on the desktop I've built a cocoa app which uses the GCDAsyncUDPSocket library to bind a port and contact the ec2 server, where a java app using apache's mina library stores the sockets external ip/port and associates it with a username passed in the payload.
the iphone, which is on the AT&T network runs an app which uses the same GCDAsyncUDPSocket library to contact the ec2 server with the same username, which then the ec2 does a lookup for the username, finds the desktops info and informs the desktop of the iphones address and the iphone of the desktops address.
now the iphone & the desktop know about each other they start shooting off packets at each other in hopes to get a punched hole.
in theory this should work, but maybe I am missing something about mobile networks that would make this difficult? But then again running a simple udp echoer on a 4th external computer to manually msg the desktop did not work either, so maybe its my router, but I don't see how that could be as all my tests show that the port the desktop asks for is the same one assigned by the router.
I've been at this for nearly two weeks with little progress and any tips would be appreciated!
"once I bind my socket on my home-network, the port is the same to the outside world as it is locally"
I highly doubt that. To traverse NAT given peers A and B which have sent datagrams to a 3rd party: S you need to send datagrams from A to B and vice versa using their public IPs as seen by S and their port as seen by S (i.e. not the port A, B are bound to from their point of view).
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I am a newbie in networking and learned about bridging concepts .I have a device which functions as bridge which works in transparent mode and filter mode.In the latter mode , whenever the packet is received to Ethernet port (which is bind to bridge ports of bridge) it floods to other Ethernet ports except the received one through bridging, If the mac address is not learned .How can i ensure this ? can anyone suggest a method to test this.
Every Ethernet switch you can find is a bridge. It learns MAC addresses from ingress frames and uses this MAC table for efficient forwarding. In the unlikely event of an unknown destination address is mimicks a repeater and outputs the frame to all ports but the one it was received from.
If you connect several computers with a bridge/switch and run a packet capture on all of them you'll see that you won't see traffic between two computers on a third computer. Some - broadcast - traffic - will show up on all of them, e.g. when you start a connection and ARP is requesting the destination MAC address for the destination IP address.
Is there a simple guide from where I can start creating a stun / turn and signaling server ?
I spend over a week searching for those things and couldn't find any guide where I can say:
okay, I am on the right track now - this is clear.
So far, everything is so abstract without any examples.
This is what I'm trying to achieve: a simple video stream on my local network where I'll have a server with installed usb camera on it, and an application on my iis which will connect to the usb camera and stream it to the clients, and every time when a client opens the application, will see the video stream from the server camera.
Note: since I want to use it on my local network do I really need a stun/turn server, or is there a guide that shows how to avoid it ?
Media streamed over dedicated servers HTTP/HTTPS rarely needs a NAT traversal solution. Instead, just have your web server with camera attached, on the public Internet or behind your NAT with port-forwarding enabled.
There are LOTS of streaming media solutions available as open source, free downloads, or commercially sold. A good list is here:
https://en.wikipedia.org/wiki/List_of_streaming_media_systems
I have a raspi 2 with a WiFi dongle and is setup to act as an access point/router. I also have 2 BeagleBone Blacks that also have WiFi dongles and they are connected to the raspi's network as well as a 9 axis sensor (accelerometer, gyro, etc). But I am unsure on how to send data from one board to another. And it has to be wirelessly.
If your RPi2 is configured as an access point, it must be running dhcpd on it. You will have to configure BBB to connect to RPi's wifi network and make use of some server client program (Could be in any language) to exchange the data. It should not be very difficult if you know what you're doing. I suggest you to break things in part and conquer, like
If you're able to ping Rpi from BBB and vice versa to check your both wifi configuration.
Once done, how about taking TCP server client code from web and test it to exchange simple strings.
and so on...
Hope it helps.
I don't know anything about wireless protocols. With this quick setup i want to get inside. I just want to write a windows desktop application which receives only a couple of bytes of data from a mcu+wifi module "NodeMCU" which is connected to the same router. I can write a simple desktop app with visual studio. But sending data over ip has many methods as far as i read.
What is the simplest way to achieve? (I'm experienced in STM32 mcu's and electronics except internet protocols.)
You can send the data from the embedded board (with the mcu) to a TTL-To-WiFi module. Then from your PC application you should open a socket and connect to the module IP to listen in the correct port the data from your board.. There are a lot of module in the market used as "bridge" or converter: you have only to setup in it the local IP address, the destination IP (your PC) and the TCP port where you want to send data. From point of view of the board you use a standard USART and the message is sent to the destination IP. In your PC application you should be able to create a socket and connect it to the wi-fi module.
Well..I have found some third party application regarding sending data from com port to IP. but I have not found any basic tutorial regarding them. so can anyone help me with this? I have a GPS device which I will connect to my laptop through usb to serial adapter.Now I need to send that data from a laptop to another laptop on same network. Can I use putty to view that data in another laptop(receiver)? Is virtual serial port driver meant for this kind of application?
If you do not want to write your own tool for it, you can simply use ncat and set up a daemon that reads piped data from one process and broadcasts it to all connected clients.
If you want something that reads the data from the serial port and then transmits it to clients, you'll need to write a server application that accepts connections and sends data around, but there's entire books on this. It should be easy to do for your purposes as written here, but it depends on the amount of control you need.
Alternatively you can use a virtual serial port application as you had mentioned, which might be the easiest route. The two devices will need to be on the same network unless the application supports TCP based virtualization instead of the common Ethernet based implementation.
This Python script works very well as a free "device server". Just enter the serial port configuration and the IP address and port information.
https://github.com/jaredly/pydbgp/blob/master/symbian/serial_tcp_redirect.py
This can work on both Windows and Linux.
You need pyserial.
You can always try using stand alone hardware such as the SENA LS100 device server.