Without nasty look-aheadses: 

>perl -wMstrict -le
"my $ma = '525400eb8b36';
 $ma =~ s/..\K\B/:/g;
 print qq{'$ma'};
"
'52:54:00:eb:8b:36'

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In reply to Re^2: Insert colons into a MAC address by AnomalousMonk
in thread Insert colons into a MAC address by mantager

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