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print "Enter the IP-range e.g. 192.168.2.0!\n";print "IP-range: ";my $range = <STDIN>;while ($range !~ /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/){ print "Wrong IP-range. Enter right IP-range e.g. 192.168.2.0!\nIP-range: "; $range = <STDIN>;}