Cannot change mac address


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# 1  
Signal Cannot change mac address

ubuntu / xubuntu 13.10 and 14.04 (this issue should exist in debian as well)

I use wifi to connect to internet. I would like to change the wifi card mac address before connecting. Let's call the original mac address, macA, and the new mac address, macB.
I do the following:

Code:
ifconfig wlan0 down && ifconfig wlan0 hw ether <macB> && ifconfig wlan0 up

then I check the new mac out:
Code:
watch -n 1 'ifconfig wlan0 | grep HW'

It works: macB appears

as long as I stay without trying to connect to internet, macB stays in place.
as soon as I try to connect to internet, the system gets back to macA instantaneously

So I disabled networking in Network Manager, and erased all existing connections. I performed the above operation, and enabled networking again in Network Manager, the issue remains

I have also tried:
Code:
ifconfig wlan0 down && ip link set wlan0 address <macB> && ifocnfig wlan0 up

I have also tried to put
Code:
'sudo service networking stop'

(which should be the same as disabling networking from Netwok Manager)., do all this, and start networking service again but the issue remains.

I absolutely need to understand what's happening in the system;

Even if you do not have the answer, please give me some leads I can dig in.

Thanx in advance folks!

---------- Post updated at 08:23 AM ---------- Previous update was at 08:20 AM ----------

just one more thing:

I used macchanger (which exists in ubuntu/xubuntu universe repositories) and have the exact same issue.

I asked the author a feedback regarding this issue but no answer so far.
# 2  
Maybe you should take a look at your arp cache before and after.... and also your arp cache TTLs
# 3  
thank you.

I start my laptop, so the cache should be empty , anyway, I issue:
Code:
arp -n

there is no entry for wlan0. Anyway, I flush everything:
sudo ip -s -s neigh flush all
-> msg: Nothing to flush

After that, the issue remains.

---------- Post updated at 09:31 AM ---------- Previous update was at 08:51 AM ----------

I could finally make it working !
It looks like my network manager did not stop correctly from gui:
so doing (as root)
Code:
service network-manager stop && ifconfig wlan0 down && macchanger -A && ifconfig wlan0 up && service network-manager start

it works!
I need to tcpdump just to be definitively sure the fake mac is given to the wifi spot.
thanx for reading guys.
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