use warnings;
use strict;
use Regexp::Common qw/net/;

my $output = "ae4.5784     up    down inet     182.75.123.121/30";

if ( $output =~ /\b$RE{net}{IPv4}\b/ ) {
	print "There IS an IPAddress in the output string\n";
}
else {
	print "There is NO IPAddress in the output string\n";
}