I'm using "ARDUINO mega-2650" with ETHERNET shield based on "WIZNET W5100" for connecting my ARDUINO to ETHERNET devices such as a switch, router, local pc, meters, etc.
In my application, I want to accept data from local devices connected in LAN and transfer that data to my SERVER application. basically, my ARDUINO will act as a transparent gateway.
Currently, I'm using TCP protocol to connect with my SERVER application and local devices present in LAN. hence my ARDUINO is working as a MASTER for local devices and CLIENT for my SERVER application. with TCP protocol my ARDUINO is working fine, but this method is limited with devices that support TCP application for communication only.
As of now, I want to connect my ARDUINO to an "ETHERNET METER MACHINE" which does not follow TCP protocol, hence I'm not able to process or accept any data from it. This "ETHERNET METER MACHINE" only sends data to the particular IP address in form of IP packets.
Can anyone suggest me a way to access all data coming at my IP address in ARDUINO without using any specific higher level protocol like TCP or UDP. For transferring or redirecting that data to the server application, TCP is fine. Is there any reference for pure "IP PACKET processing", access HEADER of each data packet for fetching any information like "SOURCE IP ADDRESS", "DATA LENGTH" etc. As I'm not very well aware of ARDUINO functions and libraries, can anyone guide me for above IP packets extraction part, any inputs will be highly appreciated.
Thanks and regards
Aatif Shaikh
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I played a bit with the official dpdk by setting up the environment and running some example applications. Then I found out about the UDPDK which combined the DPDK with the UDP stack.
I already have set up the environment for UDPDK as per documentation and then ran the sample app 'pktgen' (both in the local VM and on the public server). Now as far as I understand, this project's aim was to send pure UDP packets between connected devices.
I tried to send UDP packets from VM1(using DPRK) to VM2(normal) and tried to receive packets through a normal UDP receiver (java app) and succeeded, Also was able to send from one server(using DPDK) to another server (normal & both servers are connected to same switch as I could arping between them)
Edit :
My next target / main goal is to send/receive UDP packets from/to 1 public server (using DPDK) to another public server (normal & they are not connected, and no control over switch). Then I came to know about Open vSwitch and been told that this can be the way though I saw DPDK-OVS being used between VM's mainly. Is it really possible to send/receive UDP packets from/to remote public server using DPDK-OVS and if so then how?
Thanks in advance for any help.
For the question can one send UDP packets between 2 servers which are remotely connected (not connected directly or through the switch); the answer is yes, one can do the same without any external or 3rd party switching applciation
Reason:
packets traverse through the local network using Ethernet and VLAN
packets traverse through the remote network using MPLS, IP address or tunnel protocols.
So as long a valid packet with ethernet, vlan, IP, UDP is constructed sending it locally or remotely is possible.
How to do it:
Ensure the port used supports VF
create a VF instance and bind to DPDK
use DPDK API such as pktmbuf_alloc, mtod, eth, IP, udp to create the desired packet.
send a packet on VF interface using tx_buffer or tx_burst.
As long as the right MAC address, VLAN and|or MPLS is right external routing is taken care.
If packets are travelled through the tunnelling via NAT, ip-in-ip or GRE|Geneve, then we have 2 options
Prepare the NAT, tunnelling in DPDK and send over a physical interface
send the custom packet from the DPDK application using TAP PMD into the kernel, using network IP route tables the packets will be forwarded with appropriate tunnelling.
The above second approach takes care of neighbour discovery and tunnelling overhead.
hence the use of DPDK-OVS or OVS or any virtual switch does not solve the underlying issue.
DPDK-OVS provides DPDK vhostuser/vhostuserclient type port as virtual (virtio) device to VM. to VM, the virtio device in VM is just like any other normal network device, the UDP applications runs on VM does not care what underlying network devices the VM runs, UDP receives/sends packet through Linux network stack. you could run another userspace stack on VM and UDP applications runs on top of the userspace stack to bypass VM Linux stack.
I am currently working on a hobby project where I am using a PIC controller and a sim900 modem for remote monitoring, over a GPRS connection.
I can upload data from my remote device on to the server in regular intervals.
Now I would like to send some control signals to the device from the server, but how do I find which device to send data to? I need to know the IP address of the device which is assigned dynamically.
Is there a static IP on GSM modem, or can anyone please suggest a solution for this?
You need to contact your service provider(SIM card providers) to assign a static IP for your SIM card.
Other option is you have to develop a simple application layer protocol for data transfer over TCP/UDP in which once the connection is established your modem should send its identity(Name/ID etc.)
On the server side you need to write the code in which you have to maintain a dynamic table of modem details and socket number. When the modem is connected you can send data over the same socket for control commands.
I am new to network programming and try to understand managing traffic via TUN/TAP interface.
Since I have almost nonexistent system programming skills, and feel confident on Java; I use OpenVPN tun/tap driver and ready made Java binding for it. It works on TAP mode.
As an example application I am trying to imitiate no encryption, no authentication client server VPN application.
I can catch Ethernet Frame packets, but for the routing part, I failed miserably. (I can modify route/arp tables.)
Do anybody know how OpenVPN send packets from client to server, and from server to target. Opening sockets from Java looks like an alternative; but I was hoping that modifying packets(change IPs and/or MAC addresses) and writing back to the virtual tap interface would be enough. Is it so?
Can I inject packets to send other locations, or by default received packet moves towards application layer?
-- Edit:
Scneario
Client Tap0 _____ Server Tap0 ______ Target
Eth0 Eth0
Target: Ping from client, move through tap interfaces, target see only server ip (anonymization)
What I achived so far.
Catch traffic at client tap0 interface.
I coulnt forward traffic at server Tap so to fasten things I used Java socket programming between client-server.
Now I read packets from socket at server, and try to OpenVPN Tap driver's write method to move forward but I am not sure where do I fail. I see packets with tcpdump at server tap0, but they do not pass to server eth0.
My most important question is if I modify packet(ip, mac address) and call write method, is it possible that packet moves forward. (Or does it move to application layer whatever you change??)
Any help would be appreciated.
1. Routing is a Layer 3 (IP) problem and handled by the OS. As for the Ethernet frames on Layer 2, you have multiple options. In any case, you'll have to parse the incoming packets' headers and extract the MAC address, and decide based on the MAC where to pass the packet: To a specific client, all clients (broadcasts) or the local tap interface.
Option 1: On each client, use a tun device, and let the server use a tap device. Assign pseudo MAC addresses to each client, respond accordingly to ARP requests from the server's OS and let the OS on the server take care of the rest. Applicationwise, you'll only have to forward all incoming packets to the tap device and all outgoing packets to the client to which you assigned this MAC.
Option 2: Let the clients choose their own MAC address and forward ARP-requests through the network. The server application has to decide for incoming packets from a client whether to forward the packet to a client, or send it to the local tap device if the address matches the local device's MAC.
In both cases, clients pass all packets from their local tun/tap device to the server and vice versa.
2. You can do almost anything. A packet is only "received" when you decide to write it to the tap device, and you can of course temper with any packets, or inject new ones, ...
As a final comment, I've found that toying with tun devices is conceptually simpler, because they work on Layer 3. You'll have to open a tun device on the server for each client, but within your application you'll have to do nothing but to forward anything coming from the device to the single client, and vice versa.
I am trying to configure my laptop to be able to Wake On LAN via Magic Packets. I have a magic packet sniffer and it alerts me when a magic packet has been recieved(runs on target machine). The trouble is when I try to use the external ip address instead of the internal address. I have port forwarded port 9 to my internal ip(10.0.0.x, NOTE: x is only one digit). If I use the internal ip address, it tells me that a magic packet has been received. If I try the external ip address and sending from the target machine(to itself) it receives the magic packet. If I send it through a different machine or a website, it does not work. I am connected via ethernet cable(CAT 5). I also have the "Wake on LAN" setting in my BIOS set to "ENABLED". Also, my computer is set to "Allow this device to wake the computer". Am I doing something wrong?
P.S.
The solution to the previous problem was to start the Simple TCP/IP Service in Windows.
To use Wake on LAN across the internet (=> wake on WAN), you must do one of these things :
Edit your router's ARP table so it can forward the magic pack to the target computer with its MAC address
Port forward to LAN broadcast address so the target computer will always receive any magic packet sent to your router until it is plugged to the router
Buy a router with a built-in wake on lan feature (like DD-WRT open source firmware)
Use a magic packet repeater to forward magic packets to the broadcast address. This one should be always powered on
I'm using the fourth option to wake my home computer from my work. I bought an Arduino Uno + Ethernet shield and wrote a little program to do the job (forward magic packet). I set a port forward rule into my router (Netgear DG834G) to forward UDP 9 to the Arduino IP address.
I wrote a tutorial about this on my personal website, it's in French but code is universal ^^ : http://www.finalclap.com/tuto/arduino-wake-on-lan-repeater-80/
I did some more research and it turns out that unless the router itself has a built in management and can be accessed publicly, WoL will not work behind a router. WoL will work however if you have a device already inside the network send the magic packet to the target machine. THat completely destroys the point of WoL!
I am trying to send data using the AsyncUDPSocket class. And I can send data using the iPhone simulator over the wire to another machine that is running a simple C-coded listening server. I can also receive data over the wire using a client connected to the simulator(server). However, when I tried the same over Wifi, using the simulator, I could only send data but not receive any data.
I read on another post, that unicast data makes this possible. How can I acheive this using AsyncUDPSocket?
Thanks,
Angelo.
Ok, I figured this out. A newbie kind of thing, really.
When I set my Mac network preferences to Ethernet, I get an IP for me to communicate. However, when I turn Airport(Wi-Fi for more newbies) ON, and ethernet cable disconnected, I checked my network preferences, and sure enough my IP address was a different one.
Spoke to a friend (an ace in networking) and the thing clicked immediately: On WiFi networks a DHCP server allocates an IP address. This IP address has to be reserved, at the very least, at the DHCP server. Since my IP was not reserved, I had to change the IP address, in my udp_client.c file, recompile and run the client to connect.
BTW, I can now communicate between my iPhone and my PC using my local WiFi (office) network.
For any who might face the same problem, do not be assured that the IP address of your mchine is the same, when you switch from LAN to Wifi, and use the device mostly for WiFi reated testing. :)