$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;


##</code><code>##

 perl octet.pl
ab=cd=ef=01=23=
23.01.ef.cd.ab