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Generate random valid mac addresses

Terminal - Generate random valid mac addresses
openssl rand -hex 6 | sed 's/\(..\)/:\1/g; s/^.\(.\)[0-3]/\12/; s/^.\(.\)[4-7]/\16/; s/^.\(.\)[89ab]/\1a/; s/^.\(.\)[cdef]/\1e/'
2014-04-23 21:43:38
User: phil_m
Functions: sed
0
Generate random valid mac addresses

The sed script ensures that the "random" MAC address is unicast (bit 0 of first byte == 0) and local (bit 1 of first byte == 1)

Alternatives

There are 6 alternatives - vote for the best!

Terminal - Alternatives
ruby -e 'puts (1..6).map{"%0.2X"%rand(256)}.join(":")'
2010-12-08 10:01:31
User: eightmillion
3

Ruby version.

Also, a perl version:

perl -e 'printf("%.2x.",rand(255))for(1..5);printf("%.2x\n",rand(255))'
for i in {0..1200}; do for i in {1..12} ; do echo -n ${hexchars:$(( $RANDOM % 16 )):1} ; done | sed -e 's/\(..\)/:\1/g' | sed 's/.\(.*\)/\1/' ; echo; done
2010-12-04 16:44:11
User: Raymii
Functions: echo sed
2

First set the variable $hexchars:

hexchars="0123456789ABCDEF"

Change the number in the first for loop if you need less then 1200 mac addresses

h=0123456789ABCDEF;for c in {1..12};do echo -n ${h:$(($RANDOM%16)):1};if [[ $((c%2)) = 0 && $c != 12 ]];then echo -n :;fi;done;echo
2010-12-05 01:35:03
User: dabom
Functions: echo
Tags: Network bash mac
2

Doubt it actually generates valid mac addresses but this version doesn't need any external commands so it runs much faster.

Much shorter as well.

for i in {1..6}; do printf "%0.2X:" $[ $RANDOM % 0x100 ]; done | sed 's/:$/\n/'
2010-12-07 19:26:58
User: forcefsck
Functions: printf sed
Tags: Network bash mac
2

Shorter and more straightforward.

Also in perl:

perl -e 'print join(":", map { sprintf "%0.2X",rand(256) }(1..6))."\n"'
python -c "from itertools import imap; from random import randint; print ':'.join(['%02x'%x for x in imap(lambda x:randint(0,255), range(6))])"

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