Detecting Internet Connection - Cablemodem

[Mc Brain]

Does anybody have a working code to know if we have access to Internet or not through Cablemodem?

[BrandonTurner]

probaly not the correct way... but you could ping google

[Aaron Young]

Sending a request to a remote node is really the only reliable
way to know whether you're connected to the internet or not.

Anything else will just check to see if you're on a network.

So you can do as Brandon suggested and ping a URL you know is
likely to be up when connected to the internet, better yet, have a
list of 2 or 3 URL's.

Example:

Option Explicit
 
Private Declare Function InternetOpen Lib "wininet.dll" Alias "InternetOpenA" ( _
  ByVal sAgent As String, _
  ByVal lAccessType As Long, _
  ByVal sProxyName As String, _
  ByVal sProxyBypass As String, _
  ByVal lFlags As Long) As Long
 
Private Declare Function InternetConnect Lib "wininet.dll" Alias "InternetConnectA" ( _
  ByVal hInternetSession As Long, _
  ByVal sServerName As String, _
  ByVal nServerPort As Integer, _
  ByVal sUsername As String, _
  ByVal sPassword As String, _
  ByVal lService As Long, _
  ByVal lFlags As Long, _
  ByVal lContext As Long) As Long
 
Private Declare Function HttpOpenRequest Lib "wininet.dll" Alias "HttpOpenRequestA" ( _
  ByVal hHttpSession As Long, _
  ByVal sVerb As String, _
  ByVal sObjectName As String, _
  ByVal sVersion As String, _
  ByVal sReferer As String, _
  ByVal something As Long, _
  ByVal lFlags As Long, _
  ByVal lContext As Long) As Long
 
Private Declare Function HttpSendRequest Lib "wininet.dll" Alias "HttpSendRequestA" ( _
  ByVal hHttpRequest As Long, _
  ByVal sHeaders As String, _
  ByVal lHeadersLength As Long, _
  ByVal sOptional As String, _
  ByVal lOptionalLength As Long) As Long
 
Private Declare Function InternetCloseHandle Lib "wininet.dll" ( _
  ByVal hInet As Long) As Integer
 
Private Const INTERNET_FLAG_RELOAD = &H80000000
Private Const INTERNET_SERVICE_HTTP = 3
Private Const INTERNET_OPEN_TYPE_PRECONFIG = 0
 
Public Function IsInternetReady() As Boolean
  Dim lSession As Long
  Dim lConnect As Long
  Dim lRequest As Long
  Dim lResponse As Long
  
  Const sURL = "www.microsoft.com"
  
  ' Open an Internet Session
  lSession = InternetOpen("NetReady", _
                          INTERNET_OPEN_TYPE_PRECONFIG, _
                          vbNullString, _
                          vbNullString, _
                          0)
                          
  If lSession = 0 Then Exit Function
  
  ' Create a connection
  lConnect = InternetConnect(lSession, _
                             sURL, _
                             80, _
                             vbNullString, _
                             vbNullString, _
                             INTERNET_SERVICE_HTTP, _
                             0, _
                             0)
  
  ' Generate an HTTP GET request
  lRequest = HttpOpenRequest(lConnect, _
                             "GET", _
                             sURL, _
                             "HTTP/1.0", _
                             vbNullString, _
                             0, _
                             INTERNET_FLAG_RELOAD, _
                             0)
                               
  ' Send the request, Response will be non-zero if successful
  lResponse = HttpSendRequest(lRequest, _
                              vbNullString, _
                              Len(vbNullString), _
                              vbNullString, _
                              Len(vbNullString))
 
  Call InternetCloseHandle(lSession)
  Call InternetCloseHandle(lConnect)
  Call InternetCloseHandle(lRequest)
 
  IsInternetReady = lResponse
End Function

[Mc Brain]

Thanks, Aaron. It worked!!

[Shawn N]

Just to add on to what you might already have:

Private Declare Function InetIsOffline Lib "url.dll" (ByVal dwFlags As Long) As Long
Private Sub Form_Load()
    'KPD-Team 2001
    'URL: [url]http://www.allapi.net/[/url]
    'E-Mail: [email][email protected][/email]
    'InetIsOffline returns 0 if you're connected
    MsgBox "Are you connected to the internet? " + CStr(CBool(Not (InetIsOffline(0)))), vbInformation
End Sub

[MPardo]

Pinging to detect an internet connection may not work in some cases if your ISP has disabled that capability. Due to some of the virus attacks of late, I know someone whose ISP disabled the ping capabilities.

[SkiNLaB]

Just to clairfy, Aaron young's solution doesn't ping does it... it uses HTTP to verify the connection... yeah?

Either way, I'm using it, thanks I think I'll use two sites, google and microsoft

[ZeBula8]

I can use Aaron's code with great success but only on the first time. If I then remove the network connection and test it again, it returns a success value that I am connected to the Internet when in fact I am not.

Is this checking something that is cached?

If this is the case - is there a way to clear the cache before running a check for connectivity?