use 5.010;
my @lines = ("ip:192.168.243.1", "ip:192.168.243.2" =~
    /(ip:[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})/);
say for @lines;
__END__
ip:192.168.243.1
ip:192.168.243.2