One thing that jumps out is that you are trying to bind to local port 43. This would require that the script run as root on most unix-like OS's. I'm not aware of any requirement for a whois client to bind to port 43 on the local end of the socket.

Perhaps you could try changing

my $local = sockaddr_in(43, $local_host);
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to

# the '0' lets the kernel pick the next unused port
my $local = sockaddr_in(0, $local_host);
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Additionally, checking return values and printing $! on errors might help point you in the right direction. Particularly: bind(SOCK,$local) or die "Can't bind: $!";