InetAddress.isReachable bugs or implmentation differeces in JRE1.5 vs JRE1.6

Discussion in 'Java' started by sujit, Jan 3, 2011.

  1. sujit

    sujit Guest

    Hi,

    I am trying a very simple code.

    InetAddress serverInetAddress = InetAddress.getByName(serverName);
    svrAlive = serverInetAddress.isReachable(5000);

    For some xyz server name same code returns me "true" (i..e. server is
    rechable) when I use JRE1.6

    However when I use IBM JRE supplied along with IBM websphere (It's on
    top of JRE1.5) same code returns me exception like "IO Exception
    java.net.SocketException: Permission denied: Can't send ICMP packet"

    I have not tried this so far with JRE1.5 but I hope that I will get
    same problem with that too.

    Looking at sun website for isRechable bugs there seem to be lot of
    known issues with isRechable but all those seem to be releated to
    thread safety. But I could not find anything else.

    Are there any known implementation changes (to address these kind of
    issues) for InetAddress.isReachable in JRE1.6 vs JRE1.5

    Could someone help?

    Thanks,
    -Sujit
    sujit, Jan 3, 2011
    #1
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  2. sujit

    Arne Vajhøj Guest

    Re: InetAddress.isReachable bugs or implmentation differeces in JRE1.5vs JRE1.6

    On 03-01-2011 04:34, sujit wrote:
    > I am trying a very simple code.
    >
    > InetAddress serverInetAddress = InetAddress.getByName(serverName);
    > svrAlive = serverInetAddress.isReachable(5000);
    >
    > For some xyz server name same code returns me "true" (i..e. server is
    > rechable) when I use JRE1.6
    >
    > However when I use IBM JRE supplied along with IBM websphere (It's on
    > top of JRE1.5) same code returns me exception like "IO Exception
    > java.net.SocketException: Permission denied: Can't send ICMP packet"
    >
    > I have not tried this so far with JRE1.5 but I hope that I will get
    > same problem with that too.
    >
    > Looking at sun website for isRechable bugs there seem to be lot of
    > known issues with isRechable but all those seem to be releated to
    > thread safety. But I could not find anything else.
    >
    > Are there any known implementation changes (to address these kind of
    > issues) for InetAddress.isReachable in JRE1.6 vs JRE1.5


    I believe that what isReachable actually does is implementation
    specific.

    Some implementations does a ping, other try to make a TCP
    connection to the Echo service.

    You should not rely on it.

    Try and do what you want to do and handle an exception.

    Arne
    Arne Vajhøj, Jan 5, 2011
    #2
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