Dear All, I am using EAP-TTLS authentication mechanism for between WiMAX client and AAA on Linux environment During EAP negotiation phase following steps are successfully completed. 1. Identity exchange 2. Server/Client EAP-TTLS start 3. Client Hello 4. Server Hello-Server Certificate-Server Key Exchange-Server Hello Done EAP_Failure is coming consistently during "Client Key Exchange phase". This issue is coming consistently for multiple clients during Network Entry. Following is the error from AAA. 2012/06/04 15:52:41:686525 : <FREERADIUS LOG> rlm_eap_tls: <<< TLS 1.0 Alert [length 0002], fatal unknown_ca 2012/06/04 15:52:41:686541 : <FREERADIUS LOG> TLS Alert read:fatal:unknown CA 2012/06/04 15:52:41:686559 : <FREERADIUS LOG> TLS_accept:failed in SSLv3 read client certificate A 2012/06/04 15:52:41:686579 : <FREERADIUS LOG> rlm_eap: SSL error error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca 2012/06/04 15:52:41:686593 : <FREERADIUS LOG> rlm_eap_tls: SSL_read failed inside of TLS (-1), TLS session fails. 2012/06/04 15:52:41:686605 : <FREERADIUS LOG> eaptls_process returned 13 2012/06/04 15:52:41:686618 : <FREERADIUS LOG> rlm_eap: Freeing handler 2012/06/04 15:52:41:686650 : <FREERADIUS LOG> ++[eap] returns reject 2012/06/04 15:52:41:686663 : <FREERADIUS LOG> auth: Failed to validate the user. 2012/06/04 15:52:41:686688 : [TX] Access-Reject To resolve this issue, your timely help will be appreciated. Thanks ! Rathod. Notice: The information contained in this e-mail message and/or attachments to it may contain confidential or privileged information. If you are not the intended recipient, any dissemination, use, review, distribution, printing or copying of the information contained in this e-mail message and/or attachments to it are strictly prohibited. If you have received this communication in error, please notify us by reply e-mail or telephone and immediately and permanently delete the message and any attachments. Thank you