This may work as advertised on your OS ( Linux? ), but on Win2K returns recv: Unknown error. The above link
explains why it works for some Linux implementations.
I tested it on Solaris. It should work on any decent OS.
The link you gave refers to this working with
unconnected sockets, which seems
to
be a linux-specific feature, but by adding the PeerAddr
parameter,
perl creates a connected socket, which should allow any
errors to be reported by the OS. It looks like even W2K is
reporting the returned ICMP, just not with a very helpful
error number.
Of course with UDP and ICMP you're never guaranteed a reply,
but that's not due to TTLs - all IP packets, including UDP
and ICMP, have TTL fields.
Dave.
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