Ethernet Mac Address suddenly changed

Hello all.
I experienced a really unexpected issue today when I connected my laptop as I do every day when I get to work, but found that I had no access to any of my servers / sites that I usually connect to.
When I checked my network configuration on the Network System Preferences pane, noticed that my IP (assigned by DHCP) has changed... As if this was not enough, I reviewed the "Advanced..." settings and then the "Hardware" tab to check my mac address and noticed that the one being showed, did not match the one I had saved on my records.
I'm very aware that there are software that changes the NICs mac address at will, but I have not installed any of this software on my machine.
As additional information, I connect my laptop through an Avaya telephone / extention and it has been resetted recently because I found that my telephone had an error showing on its display screen and I incline to think that the issue with my phone may have had something to do with my mac address change.
For the record, the new mac address assigned is 00:01:01:22:1d:64
Please any help will be really appreciated.
Thank you so much.
Renato

Another odd behaviour yesterday:
As many of other ML users out there, I'm experiencing frequent crashes when I quicklook a link inside Apple Mail. That was the case yesterday when I tried to preview a link without opening Safari, my Macbook panicked and rebooted... The surprise was that when the machine was up again, guess what? The ethernet's mac address changed again but this time went back to it's original number
Problem solved? I don't think so, but there is something that is messing around with my system at the lowest level... I have thought about voltage peaks on the ethernet cable, even a (Mac) virus, I'm lost here.
I examined the console logs but to be honest, I don't even know what or where to look for...
A hardware test will be a start.

Similar Messages

Ethernet MAC address has changed and I can no longer connect to the network

I have a new iMac, 21.5" running 10.6.4. It was purchased in the past month.
I am using it on an ethernet network and using DHCP to obtain the address. It has been working for the past few weeks. I turned it on today and it is failing to connect. After some digging around, it seems that the MAC address (Ethernet ID) has been reset to 00:10:18:00:00:00. This is different to the one it has been using last week.
I have not changed any network settings. Airport is working fine.
If I pull out the ethernet cable and reinsert, the machine tries to obtain an IP address. After a while, it returns with a self-assigned IP Address.
Last week, I did notice that it was taking a relatively long time (a minute or so) to obtain the IP address over ethernet. Plugging the same ethernet cable in a macbook, I am able to obtain the IP address for the macbook much more quickly.
I see that I could use ipconfig to change the interface address to what I believe is the correct address. Would this be sensible?
Why would the machine have reset the MAC address anyway?
Regards,
Neil

Dear all,
I am having the same problem with a new MacBook Pro, bought end of October - for me it became apparent for software (Matlab, Comsol) that are registered with a licence file which was created based on the MAC address, and also when trying to register the computer to the company network. That software will only work those times that the computer "knows" its real MAC. Also, I found that audible audio books, managed through itunes, will not synchronize with the ipod at those times when the MAC address is at the producer's default (00:10:15:00:00). I never had network issues other than this computer registration, - no probs at home or elsewhere - , so it will depend on the individual setup which issue users observe.
I have had long phone discussions with different Apple support people, they have done checks based on Capture Data that I sent to them via email, etc.. They can't find the problem in the software/setup and they advised me to go the Genius Bar and have those guys look at the computer's guts.
Restarting sometimes did set the MAC to the real one, also running the code that someone suggested in Terminal sometimes helped.
Other than that, looking through the web, it does not seem to be an Apple-unique problem, but certainly one would like to see support to take care of that issue for Macs soon.
Also, thanks a lot for this thread! Otherwise the support guys on the phone would not have believed my : "the Mac address changes on a daily basis" and would just have brushed me off.
All the best,
Susanne
Message was edited by: semperula

Changing ethernet MAC address

I would like to change my macbook pro Core2Duo's ethernet MAC address. Has anyone succeded in doing that? how is it done?

Not sure why you would need to, but here yah go:
For anyone who has not noticed it ... you are now able to change the system's Ethernet card MAC adress without any third party software. Just do a:
% sudo ifconfig en0 ether aa:bb:cc:dd:ee:ff
where en0 is the network interface (numbered from en0, en1, en2 ...) and aa:bb:cc:dd:ee:ff is the desired MAC address in hex notation.
Be careful...

HT5299 which is my ethernet mac address when in a retina with adapter?

Hi,
I need to get my ethernet mac address, but i have a macboock pro retina displays that only have wireless connection. I bought the gigabit ethernet adapter, but i need the mac address because the University system that will provide me the net connection needs it to allow my computer to the net.
Where can i find it?
Thanks!

Plug the adapter into the MBP-R (*) and go to System Preferences > Network > Thunderbolt Ethernet > Advanced.
(*) You may also have to plug an Ethernet cable into the adapter at least once. Mine has been plugged in, and I didn't check the MAC address before the first time, so I can't tell for sure.

Ethernet MAC address on ipod touch?

Hi,
I'm using a iPod Touch 2G (16GB, ordered this summer with a new MacBook Pro), and I'm trying to register the device with my school wireless.
The form that I have to fill out in order to request wireless access for new devices asks for system type (APPLE-IPOD), OS (IPHONE-OS), and the ethernet and wireless MAC addresses (or "ethernet hardware address"/"wireless hardware address"). These two entries can be found on computers in System Profile/Network, where you can find the MAC addresses for Airport and Ethernet.
However, I'm not sure what to do in the case of the iPod. I understand that you can find a MAC address in Settings/Network, but this only shows the Airport MAC address, correct? I can't submit the form without including the Ethernet address, and I can't submit using the same MAC address for both Ethernet/wireless. Is there somewhere else I should be looking for this information, or is this an issue that I have to bring up with the IT office directly?
Your help is greatly appreciated!

whoops, my mistake--I meant that I'd already found General/About/Settings, but the Wi-Fi address there only indicates the equivalent of the Airport MAC address, correct? Where would I find the equivalent of the Ethernet MAC address? (or if the "Wi-Fi address" on the iPod touch is equivalent to the Ethernet MAC address, what is the wireless MAC address?

How do you spoof the ethernet MAC address?

I cant seem to get this to work...
sudo ifconfig en0 lladdr 11:11:11:11:11:11
...the mac address never changes
Message was edited by: navilon

Threads seem to say you cant do it because of the hardware, but when I boot into windows i can do it just fine.
any thoughts?

Changing ethernet Mac address in Leopard 10.5.3

I am trying to change the Mac address (ethernet) of my MacBook Pro, with Leopard 10.5.3. It used to work with Tiger, with the regular command (in Terminal): sudo ifconfig en0 lladdr 00:00:00:00:00 (where the zeros represent the new Mac address). However, since I've installed 10.5.3, this doesn't work. I'd appreciate any help.
Thanks!

Thank you both. I looked at the ChangeMac program, and it looks like it should work. I simply have this problem: I can not use the Internet on my laptop, because in order to use it, I need to change the Mac address first. I am in Eastern Europe for the summer, which is why I have this problem. Do you happen to know a prompt or command I could put it?
Thanks!

Can't change MAC address of my wireless card on Windows XP

Dear Forum Members,
I have recently bought a notebook, Lenovo IdeaPad G550L (I haven't found section for the G series here on the forum) and would like to use its WiFi adapter (BCM4310 according to Everest) with explicitly changed MAC address. I installed the recommended driver, available from Lenovo's website, version 5.10.38.14. I tried the common way to change the MAC address, went to Control Panel -> Network Interfaces -> Broadcom Wireless Network Adapter -> Configure... -> Advanced -> Locally administered MAC address, and changed it to a different address (without ":" or any separator characters). Unfortunately this common solution won't work at all. Although, no error messages are produced when changing it (so it seems successful) my wireless router shows me the original MAC address of my integrated wifi card. Tried to restart my computer, my router, everything.
* Tried different drivers, downloaded a driver from HP which had a separate wireless configurator, Broadcom Wireless Utility. It worked like the driver from Lenovo (except this one hasn't got the utility), but I was still unable to change my MAC address.
* Tried a different driver from SoftPedia, version 5.10.79.14 (this is newer than Lenovo's), it didn't work either.
* Tried Nathan True's MACShift utility. It seemed to change the MAC address, but my router showed the original, so it didn't.
* Tried to look for official Broadcom drivers on www.broadcom.com but found nothing for BCM4310.
* Finally, I booted my alternative OS, the latest Ubuntu Linux, and used the kernel driver b43 for my wireless adapter. I tried to change my MAC address using the command ifconfig wlan0 hw ether .... and connected to my network. It worked, my router showed the changed MAC so the hardware (or the firmware) is capable of doing this by the right driver/firmware.
I tried to address Broadcom with the issue, sent them a letter like this post they replied that they are not competent, they wrote the following (I guess this was an automatically generated message because it got back in 10 seconds ) from [email protected]:
"As the chipset supplier, Broadcom provides driver support to our customers - the manufacturers of wireless devices - that ultimately provide products to end customers, such as wireless LAN vendors, cable modem vendors, and notebook providers. It is up to these manufacturers to provide product-specific drivers and software support to their end customers. Please contact the manufacturer of your wireless device for their current drivers"
Then I addressed Lenovo with the problem, their answer:
"Dear ******,
Thank you for contacting Lenovo, the makers of ThinkPad and ThinkCentre products. As I understand, you have purchased a Lenovo IdeaPad G550L and would like to use its WiFi adapter (BCM4310 according to Everest) with explicitly change MAC address.and you would like to know is there an official driver for Windows XP that allows you this basic feature like b43 in Linux. We apologize,Please do speak with our Idea pad technical Team at 877-453-6686 Option 1-2-1-2 for further assistance.
If you have further questions or concerns, please feel free to contact us at 866-42-THINK (84465) option number 2. We will be happy to assist at that time.
Once again, thank you for contacting Lenovo.
Sincerely,
Lenovo Websales/CustServe"
So this means I should call them and spend extra money for phone bill of international calls because of their fault of providing a basic feature that is to be expected from every single wireless card in the market. Should I believe that a guide over the phone is more efficient than a step-by-step solution or a link to an alternative driver? I'm getting kind of disappointed. At least they have understood (or copy-pasted) my problem, dutch comfort though.
Any ideas? Anyone experienced the same problem and solved it? Is there an official (or even unofficial) driver for this device for Windows XP that allows me this basic feature (like b43 in Linux)?
Thanks in advance,
str4ngS

Yes, I have posted this thread to different forums after I realized that Lenovo "customer care" is not likely to help me out and even wirelessforums.org members couldn't come up with any ideas for days, that's why. I have already written that helper applications like SMAC (or etherchange or macshift) don't work, because they do the same thing in the system as I change it in the driver panel, so they use the same method which simply does not work.
Locked? Definitely not. If yes, why can I change the MAC of my adapter under Ubuntu Linux using b43 open-source driver if it's really locked? Or you mean it's locked from software, because Lenovo or Broadcom didn't want their users to change their MACs or they just forgot to release a fully-functional driver? Well, then I would like to have a driver in which it's not locked, because this is a basic feature of my adapter of which the hardware is capable.
I have already contacted Broadcom, see their (automatically-generated) answer in my initial post, but I will try to do that again with more foresight.

Will my MAC Address change after updating OS?

I am using wi-fi network that needs the mac address. If I update my Firefox OS version, will the mac address be changed again?

Here is a few things that you can try.
1. Try booting to safe mode by holding the shift key while starting up.
2. Reset the SMC
3. Reset the PRAM
Hope this helps!

Create a TS Variable in MDT 2013 to set Computer Name to Wifi Mac Address

Hello,
I'm currently using the following rule to pick up the MAC address of the computer:
OSDComputername=#Right(Replace("X%macaddress001%",":",""),15)#
I have created an image for the Linx Tablets, which don't have an ethernet MAC Address, so I'd like to use the Wifi address instead (which would also help with network registration in our environment). Does anybody have a solution?
Thank you,
Garin

Hi,
I highly recommend asking this question in the MDT forum, since this question is very MDT-specific:
http://social.technet.microsoft.com/Forums/en-US/home?forum=mdt&filter=alltypes&sort=lastpostdesc
Perhaps someone who is familiar with MDT will see this, but I still think you stand a much better chance at getting a good answer over in the MDT forum.
Good luck.
Don't retire TechNet! -
(Don't give up yet - 12,700+ strong and growing)

Illegal MAC address on 5800

I have just taken delivery of 2 Nokia 5800s, one form Orange and one from Three. The wifi network I will be connecting to most often controls connectivity via a list of approved MAC adresses (the access point is a cisco WAP4410N).
When entering the 5800 MAC addresses in the WAP4410N's configuration the phone from Orange presented no problem, but the one from Three resulted in an error "MAC address must be 12 Hex characters (0-9 and A-F) with optional delimiters (: or -), and the second bit is not a odd number".
It seems the MAC address of the Three supplied phone disobeys this rule. It's MAC address is EC:9B:5B:xx:xx:xx. The Orange supplied 5800 has a more standard address starting 00:xx:xx:xx:xx:xx.
Calls to Three technical support were fruitless.
I could of course disable the wifi MAC connectivity control without compromising the security too much, but this would be a last resort.
What standards does Nokia use to assign MAC addresses?
Is there something special about MAC address assigning in relation to Three supplied phones?
Am I just unlucky? If I sent my phone back to Three for a replacement would the replacement possibly have a more "standard" MAC address?
Is there any way the MAC address can changed, spoofed etc.?

Update: There was something else wrong with this phone (radio didn't work) so I had to return it to my service provider anyway. The replacement phone had a legal MAC address so all is now well.
I would still be interested in the answers to my questions though if anyone has any wisdom in these matters.

Solaris local-mac-address setting

Hi all,
Having 10gR2 Clusterware and RAC on two Solaris 10 sparc, is it required to set the EEPROM settng local=mac-address? to true so that each network card will use its own MAC address instead of the server unified MAC address? Did anyone see it in Oracle documentation for Solaris?

In order to avoid MAC address conflicts between the primary and standby NIC's, a unique
ethernet MAC address must be assigned to each network interface (NIC) on the server. On
Solaris, this can be done by setting the "local-mac-address?" PROM variable to TRUE (the
default value is FALSE) on each cluster node.
Regards
Marc

LAN and WAN share the same MAC address -- could this be a security issue?

When I bought the AEBS(n), I was a bit surprised to see only one ethernet MAC address listed (on bottom of unit, or was it in config utility?), in addition to wireless MAC. My main router has two ethernet MACs.
So last nite, I investigated. I confirmed my suspicion that both the WAN port and the LAN ports share the same MAC address! My setup has the AEBS WAN port plugged into my home LAN's main router, and a Linux machine plugged into a LAN port of the AEBS.
View of AEBS WAN side (from main router at 192.168.1.1)
ii# arp
Seconds IP Address MAC Address
734 66.130.224.1 001120A87AF5 -- ISP router
789 192.168.1.21 0016CBC430A6 -- AEBS WAN port
28 192.168.1.33 0010DC47DC53 -- home PC
824 192.168.1.73 00065BB2F295 -- work PC
View of AEBS LAN side (from a Linux box at 10.0.1.41)
root@LKG7CAE25 # cat /proc/net/arp
IP address HW type Flags HW address Mask Device
10.0.1.1 0x1 0x2 00:16:CB:C4:30:A6 * eth0
10.0.1.1 on the LAN side of AEBS and 192.168.1.21 on the WAN side of the AEBS both use the same MAC address, 00:16:CB:C4:30:A6.
I tried to provoke some leakage between the two sides (for example with broadcast packets), but haven't been able to do it so yet. Perhaps the switch in front of the eth MAC has enough smarts to keep the two subnets separate? Still it sort of worries me, if I used the AEBS as my only router, that both WAN and LAN go thru the same ethernet MAC (same h/w). I browsed here but found no discussion on this.
Comments anyone?

.... This is why there are separate MAC addresses
for ethernet and wireless, they are physically
different networks. In the case of the WAN/LAN, both
are ethernet-type networks but are physically
distinct (this is the purpose of a router like the
AEBS), so having the same MAC address on both sides
won't cause any sort of collision nor should it be
possible to leak across networks. MAC addresses can't
be used for routing beyond the physical network.
If it is indeed two different NICs sharing a single MAC, then indeed it is not an issue as you would never want to connect these two NICs together. But is it really two NICs?
My worry is that these two subnets are on the same physical network, with some magic going on to keep them separate anyway. Do we have some picture of AEBS internals? Maybe that would answer the question...

Obtaining MAC address in C program

Hello there,
I wish to obtain the MAC address of the primary ethernet card on a Solaris OS via C. This program is invoked many times/second so calling an external program is not really suitable.
The MAC address is being obtained for the purpose of providing a low-level software lock/key system (low level meaning I am aware it's relatively trivial to circumvent).
Paul.

Hello again.
I found out that the SIOCGARP ioctl will get the ARP entry of a certain IP address in the ethernet. Root access is not required.
The following program will print the ethernet MAC addresses of all IP networks (including dial-up and 127.0.0.1).
For Dial-up and 127.0.0.1 "No ethernet address" will be reported. If you have multiple network cards it may be a problem to find out the MAC address of the main board.
On my Blade-1000 the following output is produced:
lo0: 127.0.0.1 - No ethernet address.
eri0: 192.168.178.18 - 08:00:20:FB:2F:78Here is the program:
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
main(int argc,char *argv)
    unsigned char eth_addr[6];
    int i,j,sock;
    unsigned char *p;
    struct lifconf lic;
    struct lifreq lifrs[30];
    struct lifnum num;
    struct arpreq ar;
    struct sockaddr_in *soap,*soap2;
    /* Enumerate all IP addresses of the system */
    sock=socket(PF_INET,SOCK_DGRAM,IPPROTO_IP);
    num.lifn_family=AF_INET;
    num.lifn_flags=0;
    ioctl(sock,SIOCGLIFNUM,&num);
    lic.lifc_family=AF_INET;
    lic.lifc_flags=0;
    lic.lifc_len=sizeof(lifrs);
    lic.lifc_buf=(caddr_t)&(lifrs[0] );
    ioctl(sock,SIOCGLIFCONF,&lic);
    /* Get the ethernet address for each of them */
    for(i=0;i<num.lifn_count;i++)
        /* Get IP address */
        ioctl(sock,SIOCGLIFADDR,&(lifrs[ i ]));
        soap=(struct sockaddr_in *)&(lifrs[ i ].lifr_addr);
        soap2=(struct sockaddr_in *)&(ar.arp_pa);
        *soap2=*soap;
        /* Print IP address */
        p=(unsigned char *)&(soap->sin_addr);
        printf("%s: %u.%u.%u.%u - ",lifrs[ i ].lifr_name,
            p[0],p[1],p[2],p[3]);
        /* Get ethernet address */
        if(ioctl(sock,SIOCGARP,&ar)<0)
            printf("No ethernet address.\n");
        else
            p=(unsigned char *)&(ar.arp_ha.sa_data);
            printf("%02X:%02X:%02X:%02X:%02X:%02X\n",
                p[0],p[1],p[2],p[3],p[4],p[5]);
    close(sock);
}Martin

Hyper-V MAC addresses

Hi,
I understand that each Hyper-v node in a cluster will have its own dynamic pool of MAC addresses that should be different between them. When a VM is started on a node it gets a MAC from this pool, if it's moved to another node and restarted it will get a
new MAC from the pool on that node. This is a concern for me as I don't want MAC addresses to change when VM's are restarted on different nodes, besides statically assigning a MAC address to EVERY single VM (which could be a fair few with the amount you can
host these days) is there any easier way to ensure once a VM has a MAC then it will always retain that MAC regardless of which node it is restarted on?
I am running Server 2012 R2 as the hyper-v host if that makes any difference.
Many thanks
Steve

Hi,
With Hyper-V you can configure a virtual machine to use a dynamic or a static MAC address for any given network adapter.
The default option is to use a dynamic MAC address – which means that Hyper-V will generate an initial MAC address for the network adapter, and it will regenerate the MAC
address if it believes it is necessary.
If you use static MAC addresses you need to manually specify the MAC address to use, but Hyper-V will never change it.
More information:
Hyper-V and Dynamic MAC Address Regeneration
http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/05/14/hyper-v-and-dynamic-mac-address-regeneration.aspx
Hope this helps.
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Ethernet Mac Address suddenly changed

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