MAC addresses

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#1 MAC addresses

Post by ed »

I've been doing more head scratching...this one really caught me out....

I've been concerned about how long Seb has been spending on t'internet recently so I set the parental controls on the router last night. I set it so there was a 2 hour window of down time at lunch time(12:00 - 14:00). Well 13:00 rolled round and I realised he was tapping away on roblox. mmmmm?

I checked on the router and the mac address on his pc entry had changed from what I set last night....mmm go figure!!!!.. I was always under the impression that a MAC address was sacred and set at the point of manufacture. I admit I've never thought about this before, just assumed the world was not a chaotic place at all.

I had a look inside his pc and the mac address shown in the router did not tally with the mac address shown in the network details in control panel. I would hazard a guess it has something to do with the fact that his win 10 pc is running with a wifi dongle. But nothing has changed in the set up between last night and today....so I'm mystified as to why a different mac address is showing in the router....

anybody shed any light on this?
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#2 Re: MAC addresses

Post by Nick »

AFAIK, Interface cards do have a address burnt into them, but I remember with old DEC cards you could update it. However most OS's now will allow you to create additional interfaces onto of the hardware, and these certainly have modifiable MAC address, as do virtual machines. I dont know (not looked) if the additional addresses are handled in the hardware or further up the stack. Putting an interface into promiscuous mode means its not just reading only on the reception of the correct MAC, and of course ARP relies on reading without a MAC match.

In old SUN hardware the first interface MAC address was set in the system EEPROM and copied to the interface at boot time. I know this as I moved a Solaris setup from broken to new hardware by moving the EEPROM as lots of licensed software was using that id as its reference.
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#3 Re: MAC addresses

Post by jack »

Sure it wasn't his phone you blocked? :D

Have you done and ipconfig /all to check all the MACs?
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#4 Re: MAC addresses

Post by ed »

yes, I did subsequently. I was looking in from a remote machine to the one I was putting the parental control finger on....

I beleive the router has 'days off' without informing anybody.....It deffo reported Seb's machine having mac address xyz, so that was the mac address I put parental controls on. The following day Seb's machine had a different mac address so the parental control was useless....It seems to have settled down now as the router reports the same mac address for that machine consistently between boots.

I am not convinced everything here is totally stable because I have a tplink wifi booster which I installed after ditching the homeplugs. Sometimes the router detects the booster and some times it detects the clients of the booster and sometimes both. It's easy to detect the anomolies because I double check with 'advanced IP scanner' which very often doesn't agree with the routers list.

The machine I was having problems with was not attached via the tplink booster....so that doesn't account for the change in mac address.

I'm going with the consistent mac address for the moment...but I'm watching it......the router probably doesn't realise yet that I have a big hammer in the tool box...I may educate it in the fullness of time.
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#5 Re: MAC addresses

Post by Neal »

MAC addy is burnt into the Ethernet controller but you can overlay it with a soft one. IE in Windows in properties for the controller, think you may also be able to change it temporarily using ARP from the command line

Edit ....ARP is for setting the IP if you know the MAC
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#6 Re: MAC addresses

Post by ed »

back to this old chestnut.......

I was having such a great time trying to figure out why Seb's machine kept dropping out(with a new pci wifi card) that, to avoid a total nervous breakdown, I bought a new router.....a Linksys AC1750

I thought it was justified because I'd had various network problems since the homeplugs started playing up, and I thought with a new router(with more power) I'd be able to connect everything with wifi, and also ditch the wifi extender that I was using.......

Yey!! the new router has loads of power and all clients report 120/120 connectivity.

So, a month or so later and.......every time he(Seb) reboots his computer it fails to connect to the network, and no amount of hitting the connect button will sort it. If I disable and re-enable the network adapter the machine reconnects by itself. But...with a different MAC address.

So, two issues: No connect and different MAC address.

The no connect issue seems splattered all over the internet with the finger pointing firmly at a win 10 upgrade not liking Realtek adapters....ok, but no fix.

the MAC address issue is also well present on the internet, only problem for me is that the solution, to stop the adapter changing MAC addresses involves a win 10 menu option that isn't on this machine. Internet hints at the menu options being controlled by the capabilities of the Realtek driver......and I've been backwards and forwards alternating between Realteks drivers and Microsofts drivers.....

Anybody got any further ideas?
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#7 Re: MAC addresses

Post by jack »

One of the reasons that MAC spoofing happens is to prevent tracking... i.e. it's a deliberate act by some o/s, especially with phones...

What exact version of Windows are you running (build # and last updates installed), and what Realtek interface - is it on the motherboard, in which case we'll need the motherboard model number, or is it a stand-alone card, in which case... we'll need the model number.

Also, the current driver details from Windows Device Manager.

Open a cmd window and type:

Code: Select all

getmac /v /fo list
Right click on the START button, select "Network Connections". Select the "Properties" button of your LAN and scroll down - you should see details of the controller & driver version at the bottom. There's a "Copy" button there too...

The reason for the Windows build # is that build 2004 initially had a bunch of issues that for a lot of folk were resolved by the August consolidated patches... i.e. I also had problems with the initial build, e.g. Atmel Studio 7 borked spectacularly...
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#8 Re: MAC addresses

Post by ed »

according to control panel/admin tools/system info:
the version is 10.0.19041
build 19041

I updated to version 2004
Feature update to Windows 10, version 2004
Successfully installed on ‎04/‎09/‎2020

but the problem existed before the update.

adapter is Realtek 8821AE
driver 2023.70.109.2018

I have reloaded driver various times this afternoon, alternating between Realtek own dated 2017 and this ms version from 2018...

with reference to the following site
https://it.nmu.edu/docs/disable-random- ... windows-10
para2 shows a menu entry "advanced options" which in turn allows 'random hardware address' to be turned off..
I do not have the "advanced options" menu entry

various web sites hint at this feature being controlled by the driver.

so far this afternoon I have had MAC addresses:

00-E0-4C-88-21-AF
00-E0-4C-88-21-E3
00-E0-4C-88-21-F6
00-E0-4C-88-21-34
00-E0-4C-88-21-53
00-E0-4C-88-21-5A
00-E0-4C-88-21-72
00-E0-4C-88-21-DE

after trying various web sourced fixes, you can imagine how I feel about win 10 and it's upgrades at the mo....

I have now set a static IP address and so far it has retained it's MAC address for 3 reboots....but I'm not confident this has achieved anything.
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#9 Re: MAC addresses

Post by jack »

I don't think that this is a Win 10 issue - more a RealTek driver issue that hasn't been upgraded for a couple of years...

I hate to say it, but there are a bunch of posts out there on HP and other fora with folks having issues with dropouts on WiFi based on this chip or its derivatives.

It might be an idea to simply change to an Intel or other, more stable, dongle. Loads around from 10 - 15 quid. What's your time worth?
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#10 Re: MAC addresses

Post by ed »

jack wrote: Sat Sep 05, 2020 9:36 am I don't think that this is a Win 10 issue - more a RealTek driver issue that hasn't been upgraded for a couple of years...

I hate to say it, but there are a bunch of posts out there on HP and other fora with folks having issues with dropouts on WiFi based on this chip or its derivatives.

It might be an idea to simply change to an Intel or other, more stable, dongle. Loads around from 10 - 15 quid. What's your time worth?
I appreciate you sticking with this one Nick.....
however
your last post addresses the dropouts....I haven't had any dropouts since changing the router.

one issue is the 'unable to re-connect after boot' ....I still suspect the wifi card, as your post suggests...but it's clouded by the number of reports of this occurring after a win10 update.

the other issue of the change in mac address after a reboot is still foxing me...many reports of how to fix this, but I don't have the necessary menu in win 10 to acheive this.....If the suspicion that the adapter driver makes this menu item appear are correct, then I should change the adapter here as well.

I will obtain a new adapter...bit sad as the current one is only 1 month old.
also, last time I opted for a pci adapter, for some reason thinking it would be the more stable option. Any thoughts on this?

This is one time I miss being in the work place, and having a large amount of techy experience to tap into,...I do appreciate your input.

edit:
this morning the machine booted and connected automatically...AND...it had the same MAC address as yesterday.....
whether this has anything to do with me setting a static IP address remains to be seen..but it's positive...
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#11 Re: MAC addresses

Post by ed »

I think I may have finally cracked this trixy issue...

It very much smacks of a conspiracy between Realtek and Microsoft.....snigger, just kidding.

for anyone still interested in this, and it will probably only be of interest to those setting up parental controls on a router.....

In many places on the internet there are items saying if you cant fix/nail down your wifi mac address then set a new mac address. All well and good if you have the menu item to accomplish this...some don't, and I would guess a number of them resign themselves to not being able to install parental controls. This menu item is a windows feature and it may be determined by the wifi adapter driver, or not....

solution:
1.locate registry entry relating to the wifi adapter
HKEY_LOCAL_MACHINE/SYSTEM/Current/Control/SetControl/Class/{4D36E972-E325-11CE-BFC1-08002BE10318}
2.look through the list until the correct entry is found, they are number 0001,0002,0003 etc
3.add a key in the adapter settings called 'NetworkAddress' - this key very likely doesn't exist already and enter the required mac address in the value field
I entered the mac address that the wifi card 1st presented me with when this problem started
4. when you find that this doesn't work you must set the 2nd character of the first pair in the address to 2 or 6...then it might work....

I mean, how bloody masonic is this.......!!
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#12 Re: MAC addresses

Post by jack »

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#13 Re: MAC addresses

Post by ed »

I love that SHINE can be omitted from electrical appliances. It would seem that these openreach brothers are not on the case with propper English either...snigger..perhaps they've got a crack team of editors in head office that are underused..
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