Date: Thu, 21 Jun 2001 10:50:55 +0100 From: Mark Drayton <mark.drayton@4thwave.co.uk> To: freebsd-questions@FreeBSD.ORG Subject: Re: [OT] Domain names that are just numbers -- what's this?? Message-ID: <20010621105055.B2058@tethys.valhalla.net> In-Reply-To: <NDBBIMKICMDGDMNOOCAICEOPCMAA.patrick@mip.co.za>; from patrick@mip.co.za on Thu, Jun 21, 2001 at 11:33:44AM %2B0200 References: <H0000e990840a470@MHS> <NDBBIMKICMDGDMNOOCAICEOPCMAA.patrick@mip.co.za>
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Patrick O'Reilly (patrick@mip.co.za) wrote:
> Andrei,
>
> you said: --- Original Message ---
> > Take the number and convert it to hex, then take each 2 hex digits
> > and convert to decimal.
> ... as seen in earlier mail from ravi --> [188.]63.107.146.186 ---
>
> Please forgive my ignorance, but what's the [188.] doing before the
> rest of the IP???
The problem is that an IP address is a 32 bit unsigned int (4 bytes) but
808517866170 is a 40 bit int (5 bytes). The first byte is junk, and it
appears that the MS TCP/IP stack (and FreeBSD sometimes) drops it. This
is where the 188 comes from. I don't know if this is correct, or even if
there is a document defining what to do with IP addresses that are more
than 32 bits. Pointers?
Here's a perl program that will convert the 4 lowest bytes from a
decimal IP address to a dotted quad IP addresses:
----start----
#!/usr/bin/perl -w
use strict;
use Math::BigInt;
my $dec = Math::BigInt->new($ARGV[0]);
my $i = 0;
my @ip;
while ($i <= 3) {
push @ip, ($dec >> ($i * 8)) & 255;
$i++;
}
print join('.', reverse(@ip)) . "\n";
----end----
The output is a bit ugly (I can't find out how to change a Math::BigInt
object back to a scalar... suggestions appreciated):
[mark@tethys perl]$ perl ip.pl 808517866170
+63.+107.+146.+186
Cheers,
--
Mark Drayton
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