I have a C# application that should only be used when the network is down, but am afraid users will just unplug the network cable in order to use it.
Is there a way to detect if the network cable has been unplugged?
Thanks
You could use IsNetworkAlive(). Although technically it doesn't check link state, it's probably better since it can detect wireless and dialup connectivity as well. Here's an example:
using System.Runtime.InteropServices;
class Program
{
[DllImport("sensapi.dll")]
static extern bool IsNetworkAlive(out int flags);
static void Main(string[] args)
{
int flags;
bool connected = IsNetworkAlive(out flags);
}
}
The flags param returns whether the connection is to the internet or just a LAN. I'm not 100% sure how it knows, but I'd bet it just looks to see if there is a default gateway set.
In my humble opinion, there is no certain way to distinguish between a network down and an unplugged cable. And even if there is a way, there is also a way to work around it.
Let's assume that you have a solution and let's look at some situations:
There is no network traffic, the cable is not unplugged from the computer: it may be unplugged at the other end.
There is no network traffic, the cable is unplugged: but this has always been the case, the laptop is connected via Wi-Fi, which is down at the moment.
There are several network interfaces, only the one connected to WAN is down: should your app work?
The network is actually down, in the sense you mean: someone has managed to reboot the router continuously for using your app.
You can use this
System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable()
Some network drivers are able to detect this. However you'd need to use unmanaged code to access them from C# (which may be very difficult/impossible) and the solution may not be reliable for all network adapters.
The network card will report this as a state. Tools like ethtool can display this (Link up), but that is only available for Linux/Unix.
If you can enumerate the installed network cards with a Windows API, I'm sure you'll find the flag for "link up" somewhere in there.
You could register a delegate to the NetworkChange Class. When a network change occurs, it doesn't actually notify you what happened, so you could list all the network interfaces (Using NetworkInterface), filter the ones that concern you (By checking there properties) and check their operational status.
If I really wanted to use your application and whether it will work depends on something like this, I would always be able to find a way to trick your application. Are you sure there's no better solution?
How about pinging the default gateway?
There is some code here that gets the default gateway from the registry.
To detect 'Is network cable plugged in a machine?', below piece of code works.
class Program
{
private static void Main(string[] args)
{
bool isNetworkCableConnected = System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable();
}
}
Related
I have a component that (by part) uses an internet connection. I wrote some UnitTests to ensure that to component is working. However, I would like to test the behaviour of the component without internet connections.
So, my goal is to somehow temporary disable internet, or the whole internet connection, and reactivate after test.
I would disable\enable like here local are connection in test initialization
[ClassInitialize]
SelectQuery wmiQuery = new SelectQuery("SELECT * FROM Win32_NetworkAdapter WHERE NetConnectionId != NULL");
ManagementObjectSearcher searchProcedure = new ManagementObjectSearcher(wmiQuery);
foreach (ManagementObject item in searchProcedure.Get())
{
if (((string)item["NetConnectionId"]) == "Local Network Connection")
{
item.InvokeMethod("Disable", null);
}
}
[ClassCleanup()]
// Enable local area connetcion
There are many ways in which the system could have "No Internet" and the answer really depends on what you mean.
As the accepted other answer suggests, you could simply disable the network interface. That guarantees you have no internet, but the computer also will know it has no network either.
A couple other options are
To remove your Default Gateway (this may require setting static IP settings in the control panel, though I'm sure you could do it programmatically as well)
This way, the computer still thinks it's connected, but it won't have any network access except on the local subnet
Remove DNS server settings, see above link.
This way, the computer has direct IP based access but to a regular user it would appear as if there was "no internet."
Whilst not a direct answer to your question I believe you may find some use in this tool - https://jagt.github.io/clumsy/download
I've used it at work to simulate different network conditions for an mobile app that I'm currently working on. It is possible to completely disable the network connection by setting packet drop to 100%.
I am looking for a way to connect to a non-broadcast (hidden) network via C#. This is a new area of development for me. It is a UWP application that needs to be able to manage WiFi connections. I am currently using the Windows.Devices.Wifi namespace to do pretty much everything else, but I don't know how to do the non-broadcast. I have the SSID and the password for the network. I might be missing something, and it could be really easy to do, but I am missing something. Anyone able to help me out?
You can use bssid to get the WiFiAvailableNetwork like I have done:-
await wifiAdapter.ScanAsync();
var wifiList= wifiList.AddRange(wifiAdapter.NetworkReport.AvailableNetworks.ToList());
WiFiAvailableNetwork targetWifi = wifiList.FirstOrDefault(x => x.Bssid.Equals("00:19:a9:7f:08:a0"));
According to the documentation, this can be done with the WiFiAdapter.ConnectAsync method.
public IAsyncOperation<WiFiConnectionResult> ConnectAsync(
WiFiAvailableNetwork availableNetwork,
WiFiReconnectionKind reconnectionKind,
PasswordCredential passwordCredential,
string ssid
)
Connect this Wi-Fi device to a hidden network, with the given passphrase and reconnection policy.
So I am trying to connect a bluetooth speakers from a script. I am using 32feet.net and I have successfully found the device but it doesn't work when I try to pair and connect to it.
This is the code im using to pair to device, this always fails not sure why:
private static void connected(BluetoothDeviceInfo[] dev)
{
// dev[foundIndex];
bool paired=false;
paired = BluetoothSecurity.PairRequest(dev[foundIndex].DeviceAddress, "1166");
if (paired)
Console.WriteLine("Passed, Device is connected.");
else
Console.WriteLine("Failed....");
}
Here is the code called after connected to actually connect to the device: bc is my bluetooth client var.
bc.BeginConnect(devInfo[foundIndex].DeviceAddress, BluetoothService.SerialPort, new AsyncCallback(Connect), devInfo[foundIndex]);
private static void Connect(IAsyncResult result)
{
if (result.IsCompleted)
{
Console.Write("Connected... ");
}
}
Any help would be appreciated. I am new to 32feet.net so i dont know much about this, i tried following code online to get where im at.
Try BluetoothDeviceInfo.SetServiceState. That will ask Windows to connect to the audio service on the device -- hopefully that'll do the job.
See https://32feet.codeplex.com/wikipage?title=Connecting%20to%20Bluetooth%20Services
Sometimes we don’t want our application to itself send data to/from a remote service but we want instead the local operating system to do so. This is the case for keyboard/mouse/etc with HID, networking with DUN/NAP/PAN/etc, Headset/Handsfree etc.
and then
The short answer in this case is to use BluetoothDeviceInfo.SetServiceState. This is the API equivalent to manually checking the respective checkbox on the “Services” tab of the Device dialog in Bluetooth Control panel.
Also, in these days of Secure Simple Pairing, using PairRequest is fine only if all peer devices will use old style PIN code authentication, otherwise instantiate a BluetoothWin32Authentication and then do the connect (here indirectly via SetServiceState) and handle the authentication in the authentication callback.
I'm trying to write my own controller for a USB device instead of using the SDK that comes with the product (I feel the sdk is sub-par).
The USB Device is plugged into the SAME SERVER that this application is running on.
So I decided to head over to Nuget and grab the HidLibrary
PM> Install-Package hidlibrary
and I proceeded to follow the example found on GitHub.
First I went into my control panel to verify the VendorID and the ProductID
And I dropped it into my code.
Then I set a breakpoint on the line that grabs the device, but unfortunately it always comes back null.
using HidLibrary;
public class MyController : ApiController
{
private const int VendorId = 0x0BC7;
private const int ProductId = 0x0001;
private static HidDevice _device;
// POST api/<controller>
public string Post(CommandModel command)
{
_device = HidDevices.Enumerate(VendorId, ProductId).FirstOrDefault();
if (_device != null)
{
// getting here means the device exists
}
else
{
// ending up here means the device doesn't exist
throw new Exception("device not connected");
}
return null;
}
I'm hoping it's something silly, and not some deal-breaking permissions issue regarding connecting to a USB device directly from an IIS worker.
Despite your hopes to be something silly, it is not. You have some deal-breaking permission issues. If you will browse Mike O'Brien's code from GitHub of the Hid Library you will see that it calls Win32 API functions located in: kernel32.dll, setupapi.dll, user32.dll, hid.dll (Native.cs).
The enumeration itself it's done through setupapi.dll functions. It browse all the installed devices and filters what it's need it.
So... I think it's a security issue to execute kernel32.dll code directly from a web-app in IIS with anonymous authentication, don't you?
If you really need to communicate with that HID (who knows maybe it's a temperature sensor, or something else) I would do a separate Windows service and the IIS hosted web app would communication through WCF with this service. This service would like a proxy.
Put the same code in a console application and run it. That will help you verify if it's your code or environment.
If it's environment, try using Process Monitor to see if there are any hidden access errors. Also try enumerating all devices, not just looking for the one device you're after, just to see if you can do it in ASP.NET.
#Chase, unless this is an experiment - it is best not to attempt connecting to a device from IIS process. [It's a Pandora's box if you start down this path].
Best way to do this is to have another (WCF) service as proxy to the device and expose just what you need out of the service, hook it up with your app. Feel free to ask for an example if you think that would help.
I +1 #garzanti.
is there any way to check internet connection status in linux using mono
If it's desktop app, you could query NetworkManager (which is the network connection manager on most Linux desktops) over d-bus, using the NDesk.DBus library.
See Banshee for an example: http://git.gnome.org/cgit/banshee/tree/src/Core/Banshee.Services/Banshee.Networking/NetworkManager.cs
Apart from what Michael already suggested for a desktop application, you can also do something like:
foreach (NetworkInterface ni in NetworkInformation.GetAllNetworkInterfaces ()) {
// Check that any or all of:
// -ni.OperationalStatus == OperationalStatus.Up
// -that ni.NetworkInterfaceType is ethernet or wireless80211
// -ni.GetIPProperties() has a gateway and a DNS server
// ...
}
No matter what you end up using, it won't be reliable.
I see it all the time with Windows Vista and 7 at home. I use a home network, so my computers are always "connected." However, they are not always connected to the Internet.
That said, I would recommend checking the network interfaces as Gonzalo said. It is your best bet.
I would not rely on NetworkManager being present. I hate that thing and turn it off whenever I can. It is huge, ungainly, has an ugly name, relies on junk like HAL and DBUS. Early versions permanently put me off because they didn't work unless you were logged in to a GUI. It also collected bug work-arounds for wifi that were completely ridiculous in an open-source operating system that should have just fixed the original bugs. That led to other wifi managers and the command-line not being able to work properly and people being told to use NetworkManager, only because no one ever bothered to fix the actual bug!
You could try to open your connection as it is needed. If that fails display an error message.
Alternatively, if you really need a general check (e.g. at application start) you could try to make HTTP requests to one or more omnipresent websites like google.com. (Or what ever protocol you mean by "internet").
Check out HttpWebRequest.