Determining availability of a remote machine

[Martin Pool]

On  2 Apr 2003, Warwick Mitchell <wmitchell at shed.org.au> wrote:
> On Wed, 2 Apr 2003, Kim Holburn wrote:
> 
> > It relies on an icmp reply to a udp packet (port not in use or
> > some such.  The icmp is generated by the remote machine not
> > traceroute.
> 
> indeed. The original question said that icmp wasn't suitable. So I
> assumed that meant both ways.

ICMP is a non-optional part of TCP/IP.  Blocking it altogether (if
that is in fact what is being done) is not a very good idea.

You could also try arping, assuming they're on the same segment.

-- 
Martin