topic NAS Duplicated authentication attempt in Wireless https://community.cisco.com/t5/wireless/nas-duplicated-authentication-attempt/m-p/405803#M20582 <P>Hello experts!</P><P></P><P>I have this error message "NAS Duplicated authentication attempt" in the ACS reports. Where is this error coming from. </P><P></P><P>Following is the setup. </P><P>Server: Windows 2000, SP3, Q313664_W2K_SP4_X86_EN.exe, ACS 3.1, CA all in one server.</P><P>AP: Aironet 1200</P><P>Client: Windows XP SP 2</P><P></P><P>If I try by mac alone, no problem i can get through. But if i try EAP or to authenticate the user, i get that error message. </P><P></P><P>How do I checked in the client that it is using the certificate. </P><P></P><P>I've configured the external database as Windows 2000 Database and chose the domain. But still I can't authenticate. I don't even see any log events on Windows about the user authenticating. </P><P></P><P>Anyone can help me, I'd appreciate it very much.</P><P></P><P></P><P>Regards,</P><P></P><P>Neil</P> Sun, 04 Jul 2021 17:59:38 GMT n.manlangit 2021-07-04T17:59:38Z NAS Duplicated authentication attempt https://community.cisco.com/t5/wireless/nas-duplicated-authentication-attempt/m-p/405803#M20582 <P>Hello experts!</P><P></P><P>I have this error message "NAS Duplicated authentication attempt" in the ACS reports. Where is this error coming from. </P><P></P><P>Following is the setup. </P><P>Server: Windows 2000, SP3, Q313664_W2K_SP4_X86_EN.exe, ACS 3.1, CA all in one server.</P><P>AP: Aironet 1200</P><P>Client: Windows XP SP 2</P><P></P><P>If I try by mac alone, no problem i can get through. But if i try EAP or to authenticate the user, i get that error message. </P><P></P><P>How do I checked in the client that it is using the certificate. </P><P></P><P>I've configured the external database as Windows 2000 Database and chose the domain. But still I can't authenticate. I don't even see any log events on Windows about the user authenticating. </P><P></P><P>Anyone can help me, I'd appreciate it very much.</P><P></P><P></P><P>Regards,</P><P></P><P>Neil</P> Sun, 04 Jul 2021 17:59:38 GMT https://community.cisco.com/t5/wireless/nas-duplicated-authentication-attempt/m-p/405803#M20582 n.manlangit 2021-07-04T17:59:38Z Re: NAS Duplicated authentication attempt https://community.cisco.com/t5/wireless/nas-duplicated-authentication-attempt/m-p/405804#M20583 <HTML><HEAD></HEAD><BODY><P>I had this same error on ACS and it was resolved by applying the patch referenced in Microsoft KB 885453, which is regarding a PEAP bug in XP SP2.</P></BODY></HTML> Fri, 22 Jul 2005 16:29:48 GMT https://community.cisco.com/t5/wireless/nas-duplicated-authentication-attempt/m-p/405804#M20583 paul.watkins 2005-07-22T16:29:48Z