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From: glen herrmannsfeldt <gah@ugcs.caltech.edu>
Newsgroups: comp.lang.java.programmer
Subject: Re: Ping from JAVA to IP Address
Date: Wed, 7 Dec 2011 08:59:26 +0000 (UTC)
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Arne Vajhøj <arne@vajhoej.dk> wrote:

(snip)
> Well - your post was far from complete.

> Raw sockets and ICMP are not exposed to the programmer in Java.

> But that does not prevent something inside Java to use ICMP.

As far as I know, at least for unix-like system, you need to
be setuid root to do raw sockets or ICMP.  Running java as
setuid root doesn't sound great for security.

I would think that it could do something like system("ping") 
to run the ping program (which is setuid root).

> The isReachable method will in fact attempt a ping on *nix.

> On Windows it uses the echo service.

> (it will also fallback to echo on *nix if no privilege to call ping)

-- glen