1)

$ perl -le'
use Socket;
my @tests = ( "127.1", "127.0.0.3", "10.11.12.13", "300.1.2.2" );
for my $test ( @tests ) {
    print "$test is ", inet_aton( $test ) ? "" : "NOT ", "a valid IP a
+ddress.";
    }
'
127.1 is a valid IP address.
127.0.0.3 is a valid IP address.
10.11.12.13 is a valid IP address.
300.1.2.2 is NOT a valid IP address.


2)

$ perl -le'
use Socket;
my @tests = ( "255.243.0.0", "255.240.0.0", "255.255.255.0", "255.255.
+248.0" );
for my $test ( @tests ) {
    print "$test is ", unpack( "B*", inet_aton( $test ) ) =~ /^1+0+$/ 
+? "" : "NOT ", "a subnet mask.";
    }
'
255.243.0.0 is NOT a subnet mask.
255.240.0.0 is a subnet mask.
255.255.255.0 is a subnet mask.
255.255.248.0 is a subnet mask.

[download]

In reply to Re: Parsing IPv4 Addresses and distinguishing Masks by Anonymous Monk
in thread Parsing IPv4 Addresses and distinguishing Masks by ewhitt

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