I have elm327 v2.1 bluetooth and wifi usb dongle. I want to read steering angle from a car.
OBD2 PID standards do not include this data.
So I cannot get them by asking PID.
I tried to sniff the traffic , but I wasn't able to do it with this hw yet. With AT commands I used ATMA command to read CANBUS communication inside the car, but it mostly includes OBD2 PID type messages.
CAN protocol control block in every hardware's has a block which it name is can id filter and can id mask. this block filter can massages, and just access the massages that device need , this help micro controllers to don't wasting time on Unnecessary packets.
so ELM327 cant sniff traffic ,because can filter block dont let that to see traffic
it just see the packets that can id filter access , the packets that them id is 7xx
Related
Hey Stackoverflow community :)
Im looking into making a camera stream video from a an RC device into a computer using wifi.
After considering all of the options I had Im left with two:
use UDP to transfer video in packets
use packet injection and packet sniffing on the receiving device.
I was wondering what are the pros and cons of each method (for that specific purpose of video transmission)?
after looking around I found many implementations for both ways but nowhere have they specified why one is better than the other.
few things that I have not mentioned:
I know UDP does not have error correction which can make the video weird- I dont care about the quality of the video as long as it will be recognizeable.
I dont want to use connection based protocol (TPC, etc)- I dont want to wait for handshake when I get disconnected.
thanks :)
I'm trying to do a similar thing. My take on this is basically when you use the wifi cards in monitor mode (i.e. using packet sniffing/injection) you don't actually need to be connected to that network. Typically, you still need to be connected to an Access point as a client then you can communicate using UDP through that connection. But, in this case, the UDP messages are routed to the Wifi cards and the packets are injected out without being associated with any client. Then, any 'client' just has to sniff or listen on that same channel to get the transmission. So the benefit is not only does UDP not check for lost frames/etc, but also in this case you don't need to be connected to the network to get the packets.
In my case, this is preferable, since basically you will need to connect to the AP in the former case and that would require more capable hardware on the receiver side typically (more range is needed for the association part since you need to send messages back over TCP essentially to get it connected).
FYI here are the links/repos I am using and it also is a reference to what I am talking about
https://docs.px4.io/master/en/tutorials/video_streaming_wifi_broadcast.html
https://github.com/svpcom/wifibroadcast
I am using an off the shelf 'solution' in the short term, the Accsoon Cineye Air, which basically transmits HDMI 300ft line of sight over WiFi. You need an android phone to receive it, and basically I'm using the Vysor application (paid version is $40) to mirror the screen to my desktop. It works, but the latency is still more than I want : 60ms at least from the cineeye, so you can drive it around but its not as quick as DJI which is around 30-40ms ), which is my goal.
I am looking to test a scenario, how my software will respond to disconnection of a particular CAN message coming from an external device. This external device will send many CAN messages in the bus, so I cannot control it to stop just a particular message.
Therefore, I am looking for a way in CANoe just to stop one particular CAN message coming into the bus.
Please need your suggestions here.
I tried to provide as much information here, if more is require kindly put in the comment. Thanks.
You would have to split the bus into two and configure CANoe to act as a gateway:
You need a network interface with two CAN channels.
You connect your DUT to one channel (say CAN2) and the remaining bus to the other channel (CAN1).
You then configure both busses in CANoe and add a node to both busses in the simulation setup.
This node should listen to all messages received on CAN1 and output them to CAN2 and vice versa.
If you want certain messages not to reach CAN2, you have to adapt the logic of this node.
Refer to this article in the Vector knowlegde base on how to setup a gateway between two CAN busses and how to control the message flow between those busses.
I am currently working with one of Growatt inverters, 5 KVA residential inverter, It has two ports one is RS-485 I have connected a Smart Energy Meter with it to control backpower flowing to grid, and on the other port Growatt wifi device was working, I wanted to use my own platform, I used this protocol Growatt PV Inverter Modbus RS-485 RTU Protocol and then connected wire to RS-232 with a Raspberry Pi to read the data and send it back to my server. Now the issue coming is as soon as both devices start to work then inverter starts showing an error. I cannot understand why it was not giving with the Growatt device. Is there any solution?
I want to ask some question about your problem to help you if I can :-).
Are you going to monitor inverter data on your server? If yes => so, why you don't connect your server to inverter directly (I mean by using USB to the RS-485 converter).
What is your connection type? If it is Modbus-RTU you need to find Modbus register map to get your desired data. You could find this in the inverter user manual.
Be careful about your Modbus communication configurations and settings (i.e. Baudrate, ID, Parity and Byte Size).
I'm trying to write a simple C code with WinPcap to broadcast a beacon packet and capture it in all nearby WiFi units. The code I'm using is very similar to the ones available at WinPcap[1].
The code runs fine if I create an ad-hoc network connection and join all the computers into it. However, this process of creating and joining to an ad-hoc network is cumbersome. It would be much better if, regardless of what network each computer is in, the beacon packets would be broadcasted and captured once the code is running.
As simple as this problem might sound, after some searching it seems that this is not possible to be done on windows (unless re-writing drivers or maybe the kernel):
Raw WiFi Packets with WinPcap[2]
Sending packets without network connection[3]
Does winpcap/libpcap allow me to send raw wireless packets?[4]
Basically, it would be necessary to use the WiFi in monitor mode, which is not supported in Windows[5]. Therefore, if the computers are not in the same network connection, the packets will be discarded.
1st Issue
I'm still intriguing, beacon and probe request packets are a normal traffic across the network. How they could be being sent and received constantly but the user is not allowed to write a program to do so? How to reconcile that?
2nd Issue
Does anyone has experience with Managed Wifi API[6]? I've heard that it might help.
3rd Issue
Acrylic WiFi[7] claims to have developed a NDIS driver which support monitor mode under Windows. Does anyone has experience with this software? Is it possible to integrate with C codes?
4th Issue
Is it possible to code such Wifi beacon on Linux? and on Android?
www.winpcap.org/docs/docs_412/html/main.html
stackoverflow.com/questions/34454592/raw-wifi-packets-with-winpcap/34461313?noredirect=1#comment56674673_34461313
stackoverflow.com/questions/25631060/sending-packets-without-network-connection-wireless-adapter
stackoverflow.com/questions/7946497/does-winpcap-libpcap-allow-me-to-send-raw-wireless-packets
en.wikipedia.org/wiki/Monitor_mode#Operating_system_support
managedwifi.codeplex.com/
www.acrylicwifi.com/
Couple questions I will try to answer. Mgmt and Ctrl packets are used for running a wifi network and don't contain data, I would not call these normal packets. Windows used to(I think still does) convert data packets into ethernet frames and pass it up the stack. Beacon and Probe Req pkts are not necessary for TCP/IP stack to work, ie. web browsers don't need beacon frames to get your web page. Most OS's need minimal info from mgmt/ctrl pkts to help a user interact with a wifi adapter, most mgmt/ctrl pkts only are useful to the driver(and low level os components) to figure how to interact with the network. This way the wifi adapters look and act like ethernet adapters to high level os components.
Never had any experience with Managed Wifi API or Acrylic, so can't give you any feedback.
Most analyzers that capture and send packets do it in 2-3 separate modes mainly because of hardware. Wifi adapters can be in listen mode(promiscuous mode and/or monitor mode) or adapter mode. To capture network traffic you need to listen and not send, ie. if someone sends a pkt while you are sending you miss that traffic. In order to capture(or send) traffic you will need a custom NDIS driver in windows, on linux many of them already do. Checkout wireshark or tshark, they use winpcap to capture pkts in windows and there are some adapters they recommend to use to capture pkts.
Yes it is possible to send a beacon on linux, ie. Aireplay. I know its possible to capture traffic on Android but you it needs to have rooted or custom firmware, which I would believe also means you can send custom pkts. If you are simply trying to send a pkt it might be easier to capture some traffic in tshark or wireshark and use something like aireplay to resend that traffic. You could also edit the packet with a hex editor to tune it to what you need.
I am willing to build a prototype of network appliance.
This appliance is suppose to transparently manipulate Ethernet packets. It suppose to have two network interface cards having one card connected to the outside leg (i.e. eth0) and the other to the inside leg (i.e. eth1).
In a typical network layout as in the attached image, it will be placed between the router and the LAN's switch.
My plans are to write a software that hooks at the kernel driver level and do whatever I need to do to incoming and outgoing packets.
For instance, an "outgoing" packet (at eth1) would be manipulated and passed over to the other NIC (eth0) which then should be transported over to the next hope
My questions are:
Is this doable?
Those NIC's will have no IP address, is that should be a problem?
Thanks in advance for your answers.
(And no, there is no such device yet in the market, so please, "why reinvent the wheel" style of answers are irrelevant)
typical network diagram http://img163.imageshack.us/img163/1249/stackpost.png
I'd suggest libipq, which seems to do just what you want:
Netfilter provides a mechanism for passing packets out of the stack for queueing to userspace, then receiving these packets back into the kernel with a verdict specifying what to do with the packets (such as ACCEPT or DROP). These packets may also be modified in userspace prior to reinjection back into the kernel.
Apparently, it can be done.
I am actually trying to build a prototype of it using scapy
as long as the NICs are set to promiscous mode, they catch packets on the network without the need of an IP address set on them. I know it can be done as there are a lot of companies that produce the same type of equipment (I.E: Juniper Networks, Cisco, F5, Fortinet ect.)