I was wondering that how can all different network devices have different MAC ID's.
is it hardcoded separately for each device ? (extremely unlikely..since in production nobody would like to change the code and recompile and load the program...)
or
a switch is used to set the address
or
is it loaded from the ROM ?
or something else ..
Many networking interfaces use EEPROMs that come pre-programmed with EUI-48 or EUI-64. They use EEPROMs to store configuration settings and other data anyway, so they don't have any additional cost using the pre-programmed EEPROMs other than the chips ending up slightly more expensive per 1k. Programming each device with a unique ID would however incur additional cost.
For instance, 24AA02xE is an I²C SEEPROM with pre-programmed EUI-48/EUI-64 at standard addresses. 93AA46AE48 is an SPI SEEPROM with pre-programmed EUI-48 that's directly compatible with LAN9xxx Ethernet Controllers.
I'm not affiliated with Microchip. I used their chips in a hobby project and noticed the datasheet mentioning the EUI-48 features.
Related
I am testing a custom FPGA NIC and I need to send management information (such as header info for matching) and traffic data to it using a traffic generator from within the user space.
The driver built for the FPGA is a modified version of IXGBE with DMA support for management, and also supports DPDK for kernel bypass to achieve high throughput.
I am trying to understand how the various software (driver, userspace application, etc) should be stacked/connected to each-other so I can achieve the objective of reading and writing to PCIe on the NIC using set of scripts from user space?
I have also been looking at this project
https://github.com/CospanDesign/python-pci
which is useful however based on Xilinx XDMA.
Would appreciate any help, pointers on this.
Sorry, the question is too broad. For such a broad question there is a generic answer: have a look at Inter Process Communication:
https://en.wikipedia.org/wiki/Inter-process_communication
There are variety of methods, like Unix sockets, shared memory, netlink etc, to communicate between user space processes. As well as a variety of methods to communicate between user space and kernel space.
Just pick the best for you and try to do something. If it fails, come again on SO and ask ;)
guys
I am learning Linux Device Drivers.I have a question when reading below
"Since there is no equivalent of major and minor numbers for network interfaces, a network driver does not request such a number"
so could you please tell me why network interface has no major number or minor number by design?
Thanks
Major and minor numbers are used by character devices or block devices, and this implies that the user interacts with these devices by reading from and writing to special files (nodes), so a node may be created using the two numbers (major determines the device driver whilst minor is to specify a particular device managed by the driver).
Network drivers don't need the numbers since the approach (or design, as you say) of accessing network adapters doesn't assume their representation as files or nodes. Instead, the concept of network interfaces is used. And you typically make use of these network interfaces by means of socket API (say, Berkeley sockets), and such a kernel subsystem as network stack is involved here as an intermediate agent between your application and the network driver. There is no read/write access through files.
To learn CB, I've decided to browse the services on my iPhone. I'm finding a few, but except Battery and Time, the others are "Unknown". What is it?
Some services have defined UUIDs (such a battery and time) and these are listed on the Bluetooth Developer Portal. The defined services also have a set of defined characteristic IDs
BLE also allows developers to specify their own service and characteristic UUIDs - since the chance of collision for random UUIDs is infinitesimal, there is no requirement to register these, but organisations may choose to document them. Apple's notification center service defines some, for example, and many chipset/module vendors define services to make it simpler for developers to use their modules.
Looking at my Fitbit Flex I can see device information and battery services - these are well known, as well as two unknown services which, presumably, FitBit use to transfer activity and configuration information to and from the device. Short of trying to reverse-engineer their protocol there is no other information available on these services and characteristics.
I wanted to know what NFC Execution environment means actually. In forum documents it is described as "An environment, either built into the NFCC or connected to the NFCC, where NFC applications are executed. The NFCEE may be included in entities with various form factors, some of which can be removable or replaceable.". But the Device Host(an application microprocessor like OMAP or Snapdragon) is the one which interacts with NFCC, as per my understanding in the mobile environment. Can anyone give me a example of what NFCEE can be - I mean is it another hardware module(if yes, which) or an android library to execute apps? What does "form factor" refer to?
The Execution Environment is in most cases a hardware module.
Newer SIM cards have a pin to connect the SIM to the NFC chip. Inside the SIM an application (payment for example) can run in a secure environment and talk to the NFC chip. Payment goes from a sales terminal through the NFC chip directly into the SIM without ever passing data through the application processor. So there is no easy way for malware to monitor or modify the payment process. That's a simplified view of the secure aspect.
Other execution environments are:
Embedded Secure Elements. These are in a nutshell SIM cards that are in the same package as the NFC controller chip. Your Android Phone most likely has one of these, called the SmartMX chip.
SWP (Single Wire Protocol) enabled SD-Cards. Same thing as a SIM, but in the form factor of an SD card.
The concept doesn't end here. There are for example experiments to move the execution environment to the application processor. For ARM CPUs there is the TrustZone extension which allows to execute code on the main CPU while still beeing secure.
In the Android API Execution Environments do two things:
they allow you to enable or disable the secure element by setting a route. The route configures when the secure element is active (e.g. has access to the NFC chip) and when disabled. Currently there are two routes in use: Route off (turns off the entire EE) and Route_OnWhenScreenOn (EE active when screen is on and unlocked).
For secure elements that are connected exclusively to the NFC chip (embedded secure elements) the Execution Environment also offers a secure way to exchange data from the application processor to the embedded secure element. This is used to install applications within the embedded secure element (among other things).
That's it in a nutshell.
Question: I have to come up with unique ID for each networked client, such that:
it (ID) should persist once client software is installed on target computer, and should continue to persist if software is re-installed on same computer and same OS installment,
it should not change if hardware configuration is modified in most ways (except changing the motherboard)
When hard drive with client software installed is cloned to another computer with identical hardware configuration (or, as similar as possible), client software should be aware of that change.
A little bit of explanation and some back-story:
This question is basically age old question that also touches the topic of software copy-protection, as some of the mechanisms used in that area are mentioned here. I should be clear at this point that I'm not looking for a copy-protection scheme. Please, read on. :)
I'm working on a client-server software that is supposed to work in a local network. One of the problems I have to solve is to identify each unique client in the network (not so much of a problem), so that I can apply certain attributes to every specific client, retain and enforce those attributes during the deployment lifetime of a specific client.
While I was looking for a solution, I was aware of the following:
Windows activation system uses some kind of heavy fingerprinting mechanism that is extremely sensitive to hardware modifications,
Disk imaging software copies along all Volume IDs (tied to each partition when formatted), and custom, uniquely generated IDs during installation process, during first run, or in any other way, that is strictly software in its nature, and stored in registry or on hard drive, so it's very easy to confuse two.
The obvious choice for this kind of problem would be to find out BIOS identifiers (not 100% sure if this is unique through identical motherboard models, though), as that's the only thing I can rely on that isn't duplicated, transferred by cloning, and that can't be changed (at least not by using some user-space program). Everything else fails as either being not reliable (MAC cloning, anyone?), or too demanding (in terms that it's too sensitive to configuration changes).
Sub-question that I'd like to ask is, am I doing it correctly, architecture-wise? Perhaps there is a better tool for the task that I have to accomplish...
Another approach I had in mind is something similar to a handshake mechanism, where a server maintains an internal lookup table of connected client IDs (which can be even completely software-based and non-unique at any given moment), and tells the client to come up with a different ID during handshake, if a duplicate ID is provided upon connection. That approach, unfortunately, doesn't play nicely with one of the requirements to tie attributes to specific client during lifetime.
It seems to me that you should construct the unique ID corresponding to your requirements. This ID can be constructed as a hash (like MD5, SHA1 or SHA512) from the information which is important for you (some information about software and hardware component).
You can make your solution more secure if you sign such hash with your private key and your software verify during the starting, that the key (signed hash value) is signed (only public key must be installed together with your software). One can expand such kind of solution with different online services, but corporate clients could find online services not so nice.
What you're looking for is the Windows WMI. You can get the motherboard ID (which is unique across the same type of motherboard) or many many other types of unique identifiers and come up with some clever seeded function to generate a UHID. Whoa did I just make up an acronym?
And if you're looking specifically for getting the Motherboard (BIOS) ID:
WMI class: Win32_BIOS
Namespace: \Root\Cimv2
Documentation: http://msdn.microsoft.com/en-us/library/aa394077(VS.85).aspx
Sample code: http://msdn.microsoft.com/en-us/library/aa390423%28VS.85%29.aspx
Edit: You didn't specify a language (and I assumed C++), but this can be done in Java (with a COM driver), and any .NET language, as well.
Many programs use the hostId in order to build a license code (like those based on FlexLM). Have a look at what Matlab does depending on the operative system:
http://www.mathworks.com/support/solutions/en/data/1-171PI/index.html
Also have a look at this question:
Getting a unique id from a unix-like system
Once I also saw some programs basing their licenses on the serial number of the hard drive, an maybe that is the less likely thing to change. Some would suggest to use the MAC of your ethernet card, but that can be reprogrammed.
MAC
DON'T RELY ON MAC! EVER. It is not permanent. The user can easily change it (under 30 seconds).
Volume ID
DON'T RELY ON Volume ID! EVER. It is not permanent. The user can easily change it. It also changes by simply formatting the drive.
WMI
WMI is a service. Can be easily disabled. Actually, I tried that and I find out that on many computers is disabled or broken (yes, quite often broken).
License server
Connection to a validation server may cause you also lots of troubles because:
* your customers may not always be connected to the Internet.
* your customers may connect with special settings (router/NAT/proxy/gateway) that they need to input into your program in order to let it connect to the validation server.
* they may be behind a firewall that will block all programs except a few (my case). In some cases the firewall may not be under their control (valid for MOST corporate users)!
* it is super easy to redirect your program to a local fake webserver that emulates your licensing server.
Hardware data
If you need strong protection you need to rely on hardware. Something that cannot be edited by the user. Something like CPU ID instruction available in the Intel/AMD CPUs and the serial number written into the drive's IDE interface.
The CPU ID and HDD ID are permanent. They will never change, not even after you format the computer and reinstall Windows.
It is doable. For example this library reads the hardware ID of a computer. There is a compiled demo and also sourcecode/DLL. Disclaimer: the link leads to a commercial product (19€/no royalties).