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

[sujit]

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

 

[Arne Vajhøj]

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