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POHow can a mac address be changing?
 

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  1. POHow can a mac address be changing?
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    <p>I have a rather crude licence key for my software, which finds all of the mac addresses for a machine and encrypts them, then compares them with an encrypted value held in the registry. If the value in the registry matches any of the values that I have just found, then the software will load. I would expect that I would always get the same values for the MAC addresses, but for a few machines, that's not true. Can anyone explain why they MAC addresses aren't fixed, or how to over come this problem? </p> <p>Thanks</p> <pre><code> //// GET MAC ADDRESS String sMacAddress = String.Empty; ManagementScope theScope = new ManagementScope("\\\\" +Environment.MachineName + "\\root\\cimv2"); DGCSLogger.log.Trace("Management scope"); StringBuilder theQueryBuilder = new StringBuilder(); theQueryBuilder.Append("SELECT MACAddress FROM Win32_NetworkAdapter"); ObjectQuery theQuery = new ObjectQuery(theQueryBuilder.ToString()); DGCSLogger.log.Trace("Creating searcher"); ManagementObjectSearcher theSearcher = new ManagementObjectSearcher(theScope, theQuery); DGCSLogger.log.Trace("Creating collection"); ManagementObjectCollection theCollectionOfResults = theSearcher.Get(); DGCSLogger.log.Trace("Got management objects"); //// GET VALUE FROM REGISTRY String sSavedScrambled = RegistryHelper.GetCurrentUserValue(@"Software\VB and VBA Program Settings\FMPos\settings", "LicenceKey"); String sSavedLicenceKey = String.Empty; if (sSavedScrambled != null) sSavedLicenceKey = DGCS.Common.Password.UnScramblePassword(sSavedScrambled); String sMacNoLicenceKey = String.Empty; String sMacNo = String.Empty; ///// COMPARE VALUES WITH REGISTRY VALUE foreach (ManagementObject theCurrentObject in theCollectionOfResults) { DGCSLogger.log.Trace("foreach object"); if (theCurrentObject["MACAddress"] != null) { DGCSLogger.log.Trace("foreach object: " + theCurrentObject["MACAddress"].ToString().Substring(0, 5)); String macAdd = theCurrentObject["MACAddress"].ToString(); sMacNo = DGCS.Common.Password.ScrambleMacNumber(theCurrentObject["MACAddress"].ToString()); sMacNoLicenceKey = DGCS.Common.Password.CreateMacNoPassword(sMacNo); DGCSLogger.log.Trace(": " + theCurrentObject["MACAddress"].ToString().Substring(0, 5)); if (sMacNoLicenceKey.Trim() == sSavedLicenceKey.Trim()) lkCheck.HasLicenceKey = true; } } </code></pre>
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    1. USEdmund Covington
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    1. CO_"Can anyone explain why they MAC addresses aren't fixed"_ - because they aren't. For the reason of this, ask the maintainer of the machine. It can be because of a variety of reasons. _"Or how to overcome this problem?"_ - see the 300 or so questions on _"how to implement a hardware-based software license key"_.
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    2. COI have changed the query to: theQueryBuilder.Append("SELECT MACAddress FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled=true"); This limits it to the one network adapter. It does mean that a licence key will need to be reentered if they change the netwrok adapter, but at least it means I am comparing against a constant value for the time being.
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