@Mitchell – in most cases the user wants a single string identifier for the computer, that uniquely identifies it with a distinct fingerprint that is different from any other computer. The network interface (MAC) addresses are reported by the operating system, and naturally change when you add or remove a network card or adapter. It is up to you to decide which of the MAC addresses should be included in the fingerprint: if you include all of them, it certainly makes your fingerprint unique, but might include addresses that change frequently (e.g. VPN, WiFi, or virtual interfaces). On the other hand, if you ignore too many interfaces, your SID might be easier to spoof. Different operating systems have different ways of handling network interface MAC addresses, and you should consider this as well. For example, Windows and Linux addresses are pretty stable, but MacOS constantly changes the addresses when you connect/disconnect a network interface. MacOS also changes the computer’s hostname automatically, without any user approval, which is a PITA. In short, having a stable, unique SID that is less prone to spoofing requires some thought. If you need my assistance with this, please contact me privately (altmany at gmail).

Here is my practice for regexp. For all OS, always take the first mac_add pattern in the string output.

if ispc
    [~, a] = system('getmac');
    mac_add = regexp(a, '([0-9A-F]{2}-){5}[0-9A-F]{2}', 'match', 'once');
elseif isunix % OSX and Linux
    [~, a] = system('ifconfig');
    mac_add = regexp(a, '([0-9a-f]{2}:){5}[0-9a-f]{2}', 'match', 'once');
else
    mac_add = [];
end

function profile = getMacProfile
% Retrieves all of the information from the OSX system profile and returns
% it in a structure, replacing spaces with underscores in the names and
% removing the attributes in parentheses.

[~,out]=system('system_profiler SPHardwareDataType');
theLines = splitlines(out);
for i = 1:length(theLines)
    if ~isempty(theLines{i})
        try
            c=strsplit(theLines{i},': ');
            if length(c) == 2
                d=strip(c{1});
                e=regexprep(d,' \(.*\)','');
                tag =strrep(e, ' ','_');
                profile.(tag) = c{2};
            end
        catch
            % In case Apple comes up with a new entry
            disp(theLines{i});
        end
    end
end

The UDID (unique device ID) is returned in profile.Hardware_UUID. This is probably more reliable than the MAC address of EN0.

Next time don’t post on a public blog something that you don’t want to appear publicly!

oh, i see.. the new method indeed gives .00000000000000E0.50E54950537A 🙂

thank you for your clarification. could you please delete my mac addresses, they were not intended to go public 🙂

@Thomas – it’s simply a different representation of the data. Here’s an implementation that should return more legible results:

ni = java.net.NetworkInterface.getNetworkInterfaces;
macStrs = {};
while ni.hasMoreElements
    macAddr = ni.nextElement.getHardwareAddress;
    if ~isempty(macAddr)
        macAddrStr = ['.' sprintf('%02X',mod(int16(macAddr),256))];
        macStrs{end+1} = macAddrStr; %#ok
    end
end
macStrs = sort(unique(macStrs));
sid = [macStrs{:}];

Yes, they are different, this is why i am confused a bit. The SID method gives .D6CDDF05903C.8888888600000000.8888888600000000.8888888600000000
IPconfig says:
50-E5-49-50-53-7A (this is the ethernet adapter)
00-00-00-00-00-00-00-E0
00-00-00-00-00-00-00-E0
00-00-00-00-00-00-00-E0

@Thomas – in this case you have 4 separate MAC addresses, from 4 separate network devices. Run the following in your Matlab command prompt to see the list (look at the “Physical Address” rows):

system('ipconfig /all')

This again is only unique if the user does not fool around with the MACs…

@Yair – sorry, I meant not SID but that second method, where sid = .89ECC872C85C.8AFE928FEDB4.8262278A1CCA.899919B50FC9

Is it the MAC address? Because MAC address has 12 digits. My SID (this 48 digits long) is different from my MAC. Thanks.