Randomizing MAC at boot

A

athos

Hello everyone,

I've been many time willing to do some kind of little project, and, I thought about this.
A nice C and "low-level" project which may be fun to do.

Any pointers :D?
(avoid xkcd jokes, please xD).


It should (or not) change MAC of defined interfaces (that's to be defined).
Should it be loaded as a kld?

Thank you for your time.
 
This thread is about setting MAC addresses from C.
RAND_bytes(3) is supposed to be a good random number generator.

I wouldn't do that with a kernel module though (unless you want to experiment with kernel modules), as bugs in them can be quite bad.
 
Many thanks xibo!

Since what I really want to do is experiment with the kernel, I think I'll take it the hard way and try to set it up as a kld. Let's see how it goes...

I guess that with the "Designing FreeBSD Rootkits" books, I would have enough information, wouldn't I?
 
This will way You can generate a random MAC address:

Code: 
% env LC_ALL=C tr -c -d '0123456789abcdef' < /dev/urandom | head -c 12 | sed 's!^M$!!;s!\-!!g;s!\.!!g;s!\(..\)!\1:!g;s!:$!!'
f9:5b:7c:dc:c1:b8

Put that into startup script before /etc/rc.d/netif to set random MAC for wanted interfaces.
 
vermaden said:
This will way You can generate a random MAC address:

Code: 
% env LC_ALL=C tr -c -d '0123456789abcdef' < /dev/urandom | head -c 12 | sed 's!^M$!!;s!\-!!g;s!\.!!g;s!\(..\)!\1:!g;s!:$!!'
f9:5b:7c:dc:c1:b8

Put that into startup script before /etc/rc.d/netif to set random MAC for wanted interfaces.
Click to expand...

I love unix versatility... XD

I was hoping to have to deal with some C coding, and then... BAM you came with a simple solution XD

Thanks for the nice script.
 
athos said:
I love unix versatility... XD

I was hoping to have to deal with some C coding, and then... BAM you came with a simple solution XD

Thanks for the nice script.
Click to expand...

Welcome mate ;)

Generating the random MAC address is one thing, making it look like a REAL MAC requires something more, a REAL manufacturer prefix, for example check this one: http://standards.ieee.org/develop/regauth/oui/oui.txt

If You want to have a REAL MAC address that is random, take random line from manufacturers list for first 3 octets, then generate the last 3 ;)
 
I know, I know,

I once made a script that arp-pings the whole network where I was, and by downloading the IEEE OUIDs recognized the vendor :D

It was for linux, though. In fact, it downloaded that same file, and by using some grep and sed, it mades the vendors list ^^

Thank you for you time.

That sed command is crazy :p
 
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