Watch out for those dots! In a RegEx they can mean literally any character.

Here's a sample that matches either of your IP ranges-

my @tests = <DATA>; chomp @tests;

for my $test (@tests) {
    if ($test =~ /^123\.145\.14[6789]\.2$/ 
        or 
        (
            $test =~ /^135\.168\.(\d\d?\d?)\.(\d\d?\d?)$/ 
            and 
            ( $1 >= 10 and $1 <= 115) 
            and
            ( $2 >= 0  and $2 <= 125)
            
        )
    ) {
        print "YES: $test\n";
    } else {
        print "NO: $test\n";
    }
}

__DATA__
123.145.147.2
123.145.150.2
135.168.0.1
135.168.10.1
135.168.10.200 
999
123.456.178
123.456.789.09
135.168.010.001
[download]

Output:

YES: 123.145.147.2
NO: 123.145.150.2
NO: 135.168.0.1
YES: 135.168.10.1
NO: 135.168.10.200
NO: 999
NO: 123.456.178
NO: 123.456.789.09
YES: 135.168.010.001
[download]

Notice that the last IP has some numbers starting with 0 - do you want to allow this?