Randomize your WiFi MAC address on Ubuntu

Re:Randomize your WiFi MAC address on Ubuntu by throwmenow_0140 on Sunday December 03, 2017 @11:34AM (#15838256)

Here is the code I use for my mac to randomize my mac address:

    interface="en0"
    new_mac=$(openssl rand -hex 6 | sed 's/\(..\)/\1:/g; s/:$//; s/./0/2') # from stackoverflow
    sudo ifconfig $interface ether $new_mac

Edit: What's the advantage of the solution in the post? If I just change my mac address every time I join a network (even the same one), they can't track me with my randomized mac addresses. So why would I prefer to keep a stable but randomized mac address for each network I connect to for a day?

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Re:Randomize your WiFi MAC address on Ubuntu by jlgaddis on Sunday December 03, 2017 @03:37PM (#15839442)

Some bits of the MAC address are significant. You're generating all 48 bits randomly which could have some side effects.

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Re:Randomize your WiFi MAC address on Ubuntu by throwmenow_0140 on Sunday December 03, 2017 @07:14PM (#15840484)

Would love to know which side effects there are. I've never encountered any problems in all those years I use those randomly generated mac addresses.

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Re:Randomize your WiFi MAC address on Ubuntu by rurban on Sunday December 03, 2017 @04:29PM (#15839700)

    new_mac=$(openssl rand -hex 4 | sed 's/\(..\)/\1:/g; s/:$//; s/./0/2'; s/^/02:/)

is better. by using the 02: prefix for locally administered macs you avoid clashes with certain cards. I also used to randomize my local hostname.

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Re:Randomize your WiFi MAC address on Ubuntu by throwmenow_0140 on Sunday December 03, 2017 @07:32PM (#15840576)

Most of the time there are <100 devices connected to the wifis I'm connected to. I don't want to do the math now, but I expect that a collision is pretty unlikely. If you mean that some cards have problems with handling those mac addresses, I would love to hear about that.

> I also used to randomize my local hostname

Great idea, missed that. I'll integrate that in the future.

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Re:Randomize your WiFi MAC address on Ubuntu by rurban on Monday December 04, 2017 @03:54PM (#15847395)

Intel cards and Realtek cards are known to be problematic with random vendor prefixes.

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Re:Randomize your WiFi MAC address on Ubuntu by xigency on Sunday December 03, 2017 @12:13PM (#15838426)

Because maybe you had to pay to access the network and part of that involved binding your mac address.

For example, calling the hotel desk to get your device to work.

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Re:Randomize your WiFi MAC address on Ubuntu by throwmenow_0140 on Sunday December 03, 2017 @12:20PM (#15838452)

Would be interested where that happens because I've never encountered something like this (binding the mac to the access) in public networks e.g. McDonald's, hotels and other shops. I did only get access codes which could be used for a specific time where I just changed my mac address.

I only know about mac whitelisting in protected networks managed by wary administrators.

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Re:Randomize your WiFi MAC address on Ubuntu by ficklepickle on Sunday December 03, 2017 @07:44PM (#15840630)

In Canada, the ISP shaw offers ShawOpen for subscribers. There are hotspots all over the place, access control by MAC address. So I would need to provide a consistent MAC address to that SSID.

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Re:Randomize your WiFi MAC address on Ubuntu by wildrhythms on Sunday December 03, 2017 @12:42PM (#15838541)

Airports do this all the time: Wifi is free for 1 hour, after that it's $X/hour. It's simply putting a "timer" on the MAC address.

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Re:Randomize your WiFi MAC address on Ubuntu by tinus_hn on Sunday December 03, 2017 @01:43PM (#15838815)

Then randomizing that address gives you a new hour every time.

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Re:Randomize your WiFi MAC address on Ubuntu by tombrossman on Sunday December 03, 2017 @02:30PM (#15839044)

Yes, tested and working for 10+ years now. Also works well if usage is capped/throttled after a certain amount and you wish to 'reset' the connection. Try not to abuse this on a shared network obviously, but if you have a legitimate need it's very simple.

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Re:Randomize your WiFi MAC address on Ubuntu by heartbreak on Sunday December 03, 2017 @02:45PM (#15839125)

All of the universities I attended used MAC address whitelisting.

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Re:Randomize your WiFi MAC address on Ubuntu by throwmenow_0140 on Sunday December 03, 2017 @07:18PM (#15840502)

> I only know about mac whitelisting in protected networks managed by wary administrators.

Wouldn't make any sense for properly securing a network. As an attacker you could just create an evil twin (same ESSID), let some students connect to it and just use their mac addresses (and even drop their connections when they try to use the university wifi).

Edit: You don't even necessarily need an evil twin to get their mac addresses. You only have to listen to the wifi traffic and get some - even encrypted data packets still contain the raw mac address as far as I know. airodump-ng is the perfect tool to do that.

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Re:Randomize your WiFi MAC address on Ubuntu by heartbreak on Monday December 04, 2017 @10:41AM (#15844651)

I didn't say it made any sense :) This is how I was able to get my Playstation connected up in my dorm. I set my laptop's MAC to my Playstation's, then got my laptop authenticated using their tool, switched the MAC back, and the Playstation would connect up without issue.

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