Here's a thought:

$hex="abcdef0123";
 
$hex=~s/([0-9a-fA-F]{2})/$1=/g;
 
@digits=split(/=/,$hex);
 
$octets=join(".",reverse @digits);
 
printf "%s\n%s\n",$hex,$octets;
[download]

when the code is run it yeilds:

 perl octet.pl
ab=cd=ef=01=23=
23.01.ef.cd.ab
[download]

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Peter L. Berghold -- Unix Professional Peter at Berghold dot Net
	Dog trainer, dog agility exhibitor, brewer of fine Belgian style ales. Happiness is a warm, tired, contented dog curled up at your side and a good Belgian ale in your chalice.