Based on vSphere API, modify the parameters of the network card for VMS with historical stock. Its interface requires that the input parameters transmitted should include all the information of the VM's original network card (gateway, mask, DNS, etc.), but there is no interface available at present. This technical point is stuck. I want to find someone who understands R & D for advice
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I'm trying to come up with a way to sync a sqlite database between two computers.
If this were on a machine with a public IP this would not be difficult but I'm trying to find a way to make this work for ANY two devices, and most computers don't have a static IP.
What are some of the ways I can tackle this problem?
Assuming you just need to find the peers IP address...
Broadcast a Udp packet onto Lan, if machines are same lan segment. You can also try using admin scoped multicast, but mileage will vary according to the network setup and gear in use.
If trying to find two machines across the internet (assuming you can solve the NAT address translation issue), you need to bounce off a node that will hold info for you. Eg write a packet to dweet.io or sparkfun or other website that will hold store and forward data. You can also read twitter feeds etc, basically you need a known reference point to both talk too. Look into how malware create command and control networks for some ideas. Or search for rendezvous servers and protocols.
If the address range is small, probe all possible addresses. But be careful as you might trigger anti virus or ISP action
If wanting more browser based, look at webrtc, not quite what you are after but some of the techniques for discovery might be interesting.
If you have access, you can play with your DNS records. Essentially this is a variation of (2).
There are more options too, but that get more special purpose or become a bit too stelthy for general use. Also see how mesh networks are formed.
I just spoke with a phone company in Denmark, that offer "Free 3G/4G", on the phone, but they have a limitation if you create a hotspot and share the connection, this limitation is on 50GB.
How do they detect if your mobile device is sharing the connection? Do they intercept some special headers that the computer/other phones send over the connection?
MAC addresses are used at a lower layer than IP and relate to each hop or leg of an end to end communication so they don't really help with this issue.
Detecting tethered devices is quite a complicated task and there are special solutions to do exactly this. They tend to look at multiple things to try to determine if other devices are using the mobiles connection, even if the devices are spoofing or manipulating headers etc.
Examples of things a solution will look at:
number of simultaneous sessions
HTTP user-agent headers
device type
device screen size
TCP Timestamp
TCP Source Port
TCP Sequence Number
Application-based correlation to TCP flows
Node-pair correlation to TCP flows
See here for an example solution and more details of the above (this is just one example solution):
https://www.sandvine.com/downloads/general/sandvine-technology-showcases/policy-control-for-connected-and-tethered-devices.pdf
We put the question to Three, which not too surprisingly declined to
answer. However, if you think about it logically, it should be fairly
simple to detect tethering. Every device with a network connection
(including Wi-Fi) has a unique hardware identifier called a MAC
address. Assuming that the operator can trace the final destination of
the data packets, it should be able to determine that the final MAC
doesn't match your phone's.
source
Although the post is about UK operators, it should apply in Denmark.
Our application must know the following properties of the SIM Card:
a. Retrieve the SIM number (MSISDN)
b. Does it support 2G?
c. Can receive and send SMS?
d. Can send and receive data?
e. Can send and receive voice calls?
Most of the issues we are facing is becouse we cannot pro-actively query these parameters. It will be great to be able to do so thru our application (Android and iOS)
Application is distributed worldwide and should be agnostic of carriers.
Thanks so much for your input!
Yaakov
The SIM card does not store a subscribers MSISDN. Yes, according to the SIM standards their is provision for an "EF_MSISDN" file on the SIM however 90% of the operators do not populate this file. So how does the network know my MSISDN? Your phone uses the IMSI (International Mobile Subscriber Identity) stored on the SIM in file (EF_IMSI). The network maintains a "mapping" of IMSI to MSISDN within its HLR (Home Location Register).
A SIM card does not send/receive SMSs it uses the capabilities of the device it is in.
The same goes for sending and receiving data.
All of the parameters you are asking for would be device capabilities. This question should maybe be tagged under the android/ios development sections. The capability is there to query the device for its current/supported network connections, its ability to send/receive data and SMSs and possibly even the subscribers MSISDN.
Basically you will not get the information you want from the SIM card, as the information is not there.
Can someone possibly explain (within the size of a stackoverflow answer) the code required in order to emulate a network interface? I just know that there is virtualization software out there like Qemu that does this specific type of hardware emulation, but have no idea how this would work. Lots of books will show you how to create a program that listens on a TCP socket, but not create a host that gets its own IP address.
VirtualBox is open source. As a VM, with networking support, it should be sufficient to demonstrate to you what to do, along with a working implementation. https://www.virtualbox.org/wiki/Downloads
It's really depends what do you mean and what do you want to achieve. If you want emulate some real hardware you need via hypervisor's primitive emulate the most aspects mentioned in datasheet of corresponding adapter, if you want introduce some service, e.g. DNS or HTTP service visible in internal network: you need port teach some user land stack (e.g. LWIP or Slirp, or part if you need UDP only or lower) to communicate with hypervisor's internal network.
I would like to create a wireless network from a laptop. If laptops come within range, I would like it to send them a welcome message and send them a goodbye message when they leave the wifi range. Is it possible to do this in C?
Please help me out with this.
It is possible, but it is a very complex task and I don't think that programming language choice is the first thing to look into.
As a start, you can read up on Wikipedia on Wireless ad-hoc networks.
How should your messages be received and displayed on the remote side? If you want to use some existing protocol over TCP/IP, or create your own (deploying custom applications on the remote machines), you will need to mess with networks and this is not always possible as one machine can be a part of only one network. So the machines need to be not connected to anything and somehow allow you to connect to them, it involves changing network settings on all that machines (for example, setting them to join the ad-hoc network with predefined name).
If all machines automatically join the existing network, this question has nothing to do with wireless (physical layer) but with Avahi, Netbios or whatever other services allowing you to get notifications and/or enumerate devices in the network.