I am trying to send a UDP packet that I captured with Wireshark to my private game server through Scapy so that I can trigger a modded event to occur. Eventually I would like to expand on this and create something that makes these events interactive or maybe do something like display the top player of the week at some point during the games, but at this point I am not quite there.
It's a very, very old game that communicates via UDP only and has taken very little modding/anti-cheat implementation into consideration so I feel pretty confident that if I get the packet I want to the server, my game server should react as intended (or atleast I am hoping).
The problem:
I am about as green as it gets when it comes to this sort of thing.
I have spent the past 2-3 weeks reading through Stackoverflow and the Scapy documentations and pulling my hair out.
I have tried:
Reading and editing my .pcap file for the source/destination information, opening up a socket and sending in various different ways. I have unfortunately just not come across anyone with a question that I found similar enough to mine to go off of...
I am not sure it should even be done like I am trying, but here is my code so far:
>>> from scapy.all import *
>>> from scapy.utils import rdpcap
>>> import socket
>>> s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
>>> pkts=rdpcap("/home/Kali/Desktop/Packet.pcap")
>>> for pkt in pkts:
...: pkt[Ether].src= "xx:xx:xx:xx:xx:xx:"
...: pkt[Ether].dst= "xx:xx:xx:xx:xx:xx"
...: pkt[IP].src= "192.168.1.1"
...: pkt[IP].dst= "xxx.x.xxx.xx" >>I read somewhere that I didn't need ports to be updated from the pcap? But that was a local example so not sure.
...: del pkt.chksum
...: s.send(bytes(pkt))
Any help would be greatly appreciated. Thanks for taking the time to read this!
Related
I've been exploring the ADAM 6717 from Advantech.
This is the ModBus address table for said device:
At first I wanted to modify the value of the Digital output channel 0(DO0), so, as can be seen from the picture above, such address is the 0x0017.
I succeed at this by using a ModBus tool and the following settings:
Sending either "On" or "Off", turns On and off a LED connected to that output. Everything runs smoothly according to my expectation up to this point.
The problem arises when I want to read the Analog Input channel 6 or equivalently, address 400431~40044.
Since that address lies on the Analog Output Holding Registers part of the address table, I though that the following settings would accomplish the job:
However, as can be seen above, the reading shows 0.0 when there is actually 6V connected to that input (a potentiometer)
It is worth mentioning that I've made sure to enable the AI6 channel as well as setting it to Voltage mode instead of current. Also, the web utility for the device shows the AI6 reading correctly as I change the potentiometer's resistance value.
So the problem doesn't lie in the connection from the potentiometer to the AI6 but somewhere else.
Out of nothing and leaving aside what I think I know on this topic, I though of changing the function from 0x03 to 0x04
However, the response is exactly the same.
It bugs me that I can read and write values to the output coils but not the Analog output holding registers.
Is there any configuration that I might be missing over here?
Thanks in advance.
Device settings:
IP address: 10.0.0.1
Port in which the ModBus service is running: 5020
i know this forum dislikes "open" questions like this, nevertheless i'd like somebody to help untie the knot in my head, much appreciated.
The goal is simple:
read a stereo 32bit 44100 S/s I2S signal from 2 adafruit sph0645 mics
create a wav-header and store the data onto an SD-card
I've been at this for a few days now and i know that this will be much more complicated than i originally thought. Main reason: signal quality. Like most tutorials on this subject the simplest "hello world" for these mics is a looped polling for I2S-samples. Poll, fill buffer, output via serial or write to SD-card. This returns a choppy, noisy, sped up version of RL-audio. The filling of the internal DMA-buffers can be seen as constant, but the rest is mostly chaos, so
how to i sync these DMA-buffers with the rest of my code?
From experience with the STM32 HAL i'd imagine some register which can be set to throw an interrupt whenever a buffer is full, or an event which can be sent between tasks via queues. Examples on this subject either poll in a main loop with mono an abysmal sample-rate and bit depth or use pages of overkill code and never adress what it does, "just copy and it works", not good. Does the ESP32-Arduino framework provide some way to to this properly? The espressif-documentation isn't something to look forward to, since some of their I2S interface functions don't even work (if you are researching this topic as well, you too might have noticed that i2s_read only returns zeros). Just a hint into the right direction would help, i'm writing my own code anyway. Interrupts? Events? Timers? Polling for full buffers? Only you might know.
have a good one, thx
Thanks to https://github.com/atomic14/ i now have an answer for a syncing-method which works very well. This method has been tried by https://esp32.com/viewtopic.php?t=12546 who also didn't fully understand what was going on: the espressif i2s-interface offers a flag stored in an event which is triggererd every time one of the specified dma-buffers has received a full set of data, ergo, is full. It looks like this:
while(<your condition>){
i2s_event_t evt;
if (xQueueReceive(<your queue>, &evt, portMAX_DELAY) == pdPASS){
if (evt.type == I2S_EVENT_RX_DONE){
size_t bytesRead = 0;
do{
//read data via i2s_read or i2s_read_bytes
} while (bytesRead > 0);
No data is stored in this queue, but rather a flag which can then be used to synchronize dma-filling and further buffering/calculating/sending the read data.
HOWEVER this only works if you install the i2s driver in a specific setup. Instead of using
i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
in your setup, you can activate the "affinity" for events by passing a queue-handle and a lenght:
i2s_driver_install(I2S_NUM_0, &i2s_config, 4, &<your queue>);
hope this helps getting started, it sure did help me.
I have a doubt regarding read operation in I2C, bit banging. The protocol which I am following for read as below:
Start-slave address with write-ack-register loc-ack-stop. ...... Start-slave address with read-ack-read data-stop.
I am reading data as FFh which is wrong.
My doubt is, before sending the another start, do in need to send stop or can continue the another start for reading data without stop, which actually is a repeated start. Does sending a stop bit or not makes any difference. Also can someone tell what can be the possible reason if data read is FFh. But I can guarantee that write operation is successful, after seeing the scope shot. Please guide me.
Thanks
The i2c protocol works like this
WRITE:
send START
write slave address with last bit as WRITE ACCESS(0)
write sub-address: this is usually the address of the register you what to write to; if not applicable skip to 4.
write data
send STOP
Each byte you write to the slave device should be answered with an ACK if the operation was successful.
READ:
send START
write slave address with last bit as WRITE ACCESS(0)
write sub-address: this is usually the address of the register you what to read from
send START (this is a second start condition - a restart)
write slave address with last bit as READ ACCESS(1)
read data
send STOP
All write and read operations (except the last read) are answered with a ACK if successful.
So in the case of a restart you don't send a second Stop.
As far as the 0xFF read result is concerned, you need to check the datasheet of the device, but some will return this value if the data you are trying to read is not available, yet!
Hope this helps.
I just had this issue and found the reason: if you receive FFh in reading all the time, you are missing the repeated start.
here's what I'm trying to do:
I have 4 clocks and one PC on the network. I (PC) want to get the time from any of the clocks.
The idea:
Every clock uses UDP Broadcast (broadcast because I don't know the PC's IP). The PC gets a first dataset(time) and from then on only looks at datasets from this clock. (To not get confused by slight timedifferences between the clocks)
Clocks=Clients:
- socket
- bind to port 1234
- sendto(broadcast,'1234')
PC=Server
- socket
- bind to port 1234
- recvfrom(data,client_addr) //extract client_addr from first received data
- connect(client_addr) //to only receive data from this client
- recvfrom()
1: Is this the correct way to do this? Or is there a better option?
2: What can I do, if I want more than one application on the PC to get the time-data? Can I just copy the code and use it? My impression was, that port 1234 is now blocked from the first application that gets the bind.
(I guess SO_REUSEADDR won't work because only ONE application then gets the data AND I don't know which one it is going to be)
Regards
1: Is this the correct way to do this?
Yes.
Or is there a better option?
Can't think of one off-hand.
2: What can I do, if I want more than one application on the PC to get the time-data?
Use SO_REUSEADDR.
Can I just copy the code and use it?
Yes.
My impression was, that port 1234 is now blocked from the first application that gets the bind.
No.
(I guess SO_REUSEADDR won't work because only ONE application then gets the data AND I don't know which one it is going to be)
Wrong guess. Why guess about it at all? Why not try it? Much more reliable than guessing, and quicker than asking questions here too.
I have an Arduino with a WiFly shield, everything works perfectly!
The thing is, when I want to turn on an LED, I open in my
webbrowser:
192.168.1.120/ledon/
(I made a program which handles this URL).
But the thing is; when I make a request, I must wait 1-2 seconds before I can do another one.
So, it is very long, and if I want to control motors, it is just too long.
So, instead of using an HTTP request, I want to use something else which can be faster.
Something "super fast".
I just need to tell the Arduino:
- go direction 1
- go direction 2...
- turn on LED
- turn off LED
- tell me the light level (which return a int)
So it is just about a small amount of data.
Can you show me a way? (Telnet, UDP, OSC?)
For your arduino, have a look at just using sockets or even encoding the data in the URL requested.
You shouldnt get less than about 0.8 Seconds Lag maximum.
How big is your program for handling the Url /ledon/ ?
Using pure packets (usually TCP) from your computer to the arduino is faster sometimes..
But you may need to code a application to handle the packets on the pc.
There is the option of Javascript to parse data back and forth e.g. reading the light level and such.