I have tried using several commands as well as couple of examples using C/C++ but am still not able to find a flawless method that can differentiate between physical or virtual ethernet adapters. Physical means, on that available on your board or installed externally and virtual means created by virtualization apps such as VirtualBox/VMWare/Virtual PC or VPN etc.
Any pointers?
There is no flawless method. A virtual adapter can have any MAC address, including one that might have been assigned by a constructor to a physical device. And the other way around, given that one can change the MAC address of a physical adapter. You can only make an educated guess.
You might find it easier to detect if you are running virtualized at all, rather than look for specific information about the NICs. The virt-what(1) tool looks through aspects of the running system to guess if the system is virtualized or not. (The script isn't as smart as you think, but it does have a lot of small information gathering tools in one place.)
Someone intentionally trying to bypass a license check would probably not find it difficult to defeat this mechanism.
Maybe one can use mii-tool and check if it fails, which it does for virtual:
mii-tool vmbr2
SIOCGMIIPHY on 'vmbr2' failed: Operation not supported
mii-tool eno1
eno1: negotiated 1000baseT-FD flow-control, link ok
EDIT:
What is mii-tool: view, manipulate media-independent interface status
This utility checks or sets the status of a network interface's
Media Independent Interface (MII) unit. Most fast ethernet
adapters use an MII to autonegotiate link speed and duplex
setting.
https://www.man7.org/linux/man-pages/man8/mii-tool.8.html
Related
Environment:
I have an embedded linux system running with an ARM based iMX7 processor. It runs on a build from yocto linux which is very much based on Fedora.
Scenario:
My system uses Suspend To RAM feature which is linux system power saving mode that is explained quite well in this link. This is done to save power at a certain stage.
Objective:
Now, I need to keep the wifi link open during this stage. And as I read from some discussions like this, it seems to be possible to do so.
How can I do this?
Read up on similar discussions:
Reading through this discussion, it explains how to do this on a intel based desktop linux computer. But I don't have the /etc/NetworkManager on my embedded linux device. Probably there is a different way to do it on a Fedora based embdded linux system.
Can I get some suggestions on how to do this or even how to approach this?
None of the articles you quoted even suggest that it is possible to leave WiFi on - in fact one of them says it can't be done. All they provide is various tricks to make the wake-up faster.
Depends on the hardware but very likely, leaving it on is really impossible. Suspend-to-ram includes a hardware command that switches the CPU clock off, places its interconnect buses into idle state, and disables main power to all the peripherals (leaving only standby power to those peripherals that support standby mode).
I don't know if your WiFi device has support for running on standby power nor whether the embedded hardware you have has the ability to provide that power to it while the CPU is off. If that ability exists, it will likely be accessible as a kernel driver parameter.
You may be able to save some startup time when waking up from standby by providing a static configuration for your WiFi device rather than using the default automatic connection (which involves searching for a router to connect to, obtaining an IP address, etc.).
You can't just keep wifi active during sleep/resume. You can optimise reconnection speed but I believe NM and connman both do that already.
I'm searching for help and an opinion-advice for a network project, in which I'm working lately. This requires a Linux machine to be a passive network appliance.
Network packets come in from one network interface and come out from another interface ( net--eth0-->Linux PC--eth1-->net) without making any modifications on data.
The application, which is going to run on the Linux system, will change only the order of the packets. It is going to be a "silly" network emulator application.
The first implementation was made with RAW sockets, where read() is called every time a packet arrives to user space and write() is called when an Ethernet packet should be sent down to the NIC.
I would like to know if there is a more practical and direct way than RAW sockets, bypassing Linux's network stack.
If what you want is to bypass the kernel, DPDK in Linux and NetMap in FreeBSD are options to do just that.
Indeed this can be done in dpdk in Linux. There are l3fw and l2fwd sample applications in the examples folder of the dpdk tree, which may inspire you. Also consider using vpp, a fd.io project hosted by Linux Foundation, which can use dpdk.
Rami Rosen
Can mobile device bluetooth mac address be changed??
I am asking this because one part of my system depends on this security. If it can be done, how hard is this to do and how one can do that.
I know that on linux you can change it pretty easily, but that is for PCs.
Device manufacturers will not allow changing of MAC address,
MAC address is controlled and allocated by IEEE since it has to be unique.
if you are a device manufacturer you can get a bunch of addresses and keep changing them on a single device. (so theoretically is it possible)
Changing MAC is possible by the lower level drivers and typically this capability is not exposed to applications.
"I am asking this because one part of my system depends on this security."
If you are basing MAC address of blue tooth as a security consideration you are going about this the wrong way.
This is the EXACT same as banks relying on just the hotsname "back.com" to verify that the user is connecting to correct website. This is why https and SSL was invented not only for encryption but also to verify that users are who they say they are.
IE you will need to implement some sort of trust chain in order for this to be secure not some random MAC address which is technically publicly viewable (with in range) and also spoofable as has been proven by PC application/drivers.
I've never heard of any tools on Windows that can do it, only Linux. I suggest you get a Live CD of Linux and follow this walkthrough:
http://www.siddharthabbineni.com/tech/hardware/change-bluetooth-device-mac-address.html
Are there any standard implementations of Mobile IP for Linux?
If I want to support mobile IP for a network, what all needs to be done?
If I have to write code from scratch, is it likely that a kernel module will suffice or I would have to make changes to the kernel code.
I just need a bit of headstart to know where to begin.
It appears likely to me that it can be done without requiring any kernel code at all, you can achieve it by having a userspace daemon create a tun interface (much like a VPN client would typically do) and then route or encapsulate packets in whatever way is required for mobile IP. The userspace daemon may have to modify the kernel's routing table but that's ok.
Examples of the tun interface users are openvpn and Qemu.
I need to store persistent reference to third party device on an arbitrary IP network where the IP address of the devices may be static or randomly assigned by DHCP. I don't control the devices on the network and I can't rely on DNS and other ad-hoc networking protocols existing or working with the devices.
So I have been instructed to investigate using hardware addresses and ARP. This will work but I don't want to duplicate code. The kernel must manage an ARP table. On Windows you can access it using GetIpNetTable etc.
I am hoping there is an API to answer these two questions:
How do I translate from IP to MAC address? (ARP)
How do I translate from MAC to IP address? (InARP)
If not then I may have to do it more manually:
How do I read the kernel's ARP table?
How do I add an entry if I have the determined a mapping myself?
/proc/net/arp
K
ARP tables tend to be fairly local and short-lived. If you examine the protocol, the real MAC addresses are generally only provided when the given IP address is in the local subnet.
Otherwise, the packet is forwarded to the local router, which is then responsible for forwarding it.
If you do "arp -g" on Windows or "arp -a" on UNIX, you'll see the table, but I don't think it will do you any good, due to the reasons mentioned above. That command and
That's really what DNS is for but, as you say, it may not be an option for you.
You may well have to write your own 'ARP' database at your application level.
As for ARP:
You could use system("/usr/bin/arp -option_of_choice"); and parse the output, but that's an ugly hack. -- Not my recommendation.
Take a look at /usr/include/linux/sockios.h -- At the SIOCGARP, SIOCDARP, and SIOCSARP details. Those are ioctls that you can perform to manage the ARP table on linux. Of course, you'll have to perform these ioctls on a socket fd.
Here's some examples: SIOCGARP examples
I'm sure you can find many other examples in several other languages as well. As I'm assuming that you're using C.
As for RARP:
A quote from the linux rarp manpage:
" This program is obsolete. From version 2.3, the Linux kernel no longer
contains RARP support. For a replacement RARP daemon, see ftp://ftp.demen-
tia.org/pub/net-tools"
So you'll have to install rarpd on the target system.