Problema
Por padrão, o Cisco Security Manager (CSM) apresenta as seguintes cifras para comunicação HTTPS:
%ASA-7-725011: Cipher[1] : AES128-SHA
%ASA-7-725011: Cipher[2] : DHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[3] : DHE-DSS-AES128-SHA
%ASA-7-725011: Cipher[4] : DES-CBC3-SHA
%ASA-7-725011: Cipher[5] : EDH-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[6] : EDH-DSS-DES-CBC3-SHA
%ASA-7-725011: Cipher[7] : DES-CBC-SHA
%ASA-7-725011: Cipher[8] : EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[9] : EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[10] : EXP-DES-CBC-SHA
%ASA-7-725011: Cipher[11] : EXP-EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[12] : EXP-EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[13] : ECDHE-ECDSA-AES128-SHA256
%ASA-7-725011: Cipher[14] : ECDHE-RSA-AES128-SHA256
%ASA-7-725011: Cipher[15] : AES128-SHA256
%ASA-7-725011: Cipher[16] : DHE-RSA-AES128-SHA256
%ASA-7-725011: Cipher[17] : DHE-DSS-AES128-SHA256
%ASA-7-725011: Cipher[18] : ECDHE-ECDSA-AES128-SHA
%ASA-7-725011: Cipher[19] : ECDHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[20] : AES128-SHA
%ASA-7-725011: Cipher[21] : DHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[22] : DHE-DSS-AES128-SHA
%ASA-7-725011: Cipher[23] : ECDHE-ECDSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[24] : ECDHE-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[25] : DES-CBC3-SHA
%ASA-7-725011: Cipher[26] : EDH-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[27] : EDH-DSS-DES-CBC3-SHA
%ASA-7-725011: Cipher[28] : ADH-AES128-SHA256
%ASA-7-725011: Cipher[29] : ADH-AES128-SHA
%ASA-7-725011: Cipher[30] : ADH-DES-CBC3-SHA
%ASA-7-725011: Cipher[31] : DES-CBC-SHA
%ASA-7-725011: Cipher[32] : EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[33] : EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[34] : ADH-DES-CBC-SHA
%ASA-7-725011: Cipher[35] : EXP-DES-CBC-SHA
%ASA-7-725011: Cipher[36] : EXP-EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[37] : EXP-EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[38] : EXP-ADH-DES-CBC-SHA
%ASA-7-725011: Cipher[39] : NULL-SHA256
%ASA-7-725011: Cipher[40] : ECDHE-ECDSA-NULL-SHA
%ASA-7-725011: Cipher[41] : ECDHE-RSA-NULL-SHA
%ASA-7-725011: Cipher[42] : NULL-SHA
%ASA-7-725011: Cipher[43] : NULL-MD5
No entanto, se configurarmos o ASA para suportar apenas um algoritmo de criptografia forte (como AES256-SHA):
A comunicação falhará e veremos o seguinte SYSLOG no ASA:
%ASA-7-725014: SSL lib error. Function: ssl3_get_client_hello Reason: no shared cipher
E o seguinte log no CSM:
"Unable to communicate with the Device"
The Security Manager Server and the device could not negotiate the security level"
Solução
Devido a regulamentos de importação em alguns países, a implementação Oracle fornece um arquivo de política de jurisdição criptográfica padrão que limita a força dos algoritmos criptográficos. Se os algoritmos mais fortes precisarem ser configurados ou já estiverem configurados no dispositivo (por exemplo, AES com chaves de 256 bits, grupo DH com 5,14,24), siga estas etapas:
- Baixe os arquivos Java 7 ilimitados de criptografia policy.jar em http://www.oracle.com. A Cisco recomenda pesquisar o seguinte no site da Oracle:
JCE (Java Cryptography Extension, extensão de criptografia Java) Arquivos de política de jurisdição de força ilimitada Java 7
http://www.oracle.com/technetwork/java/javase/downloads/jce-7-download-432124.html
- Substitua local_policy.jar e US_export_policy.jar no servidor do Security Manager na pasta CSCOpx\MDC\vms\jre\lib\security.
- Reinicie o servidor do Security Manager.
Agora, o CSM apresentará as seguintes cifras:
%ASA-7-725011: Cipher[1] : AES128-SHA
%ASA-7-725011: Cipher[2] : DHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[3] : DHE-DSS-AES128-SHA
%ASA-7-725011: Cipher[4] : DES-CBC3-SHA
%ASA-7-725011: Cipher[5] : EDH-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[6] : EDH-DSS-DES-CBC3-SHA
%ASA-7-725011: Cipher[7] : DES-CBC-SHA
%ASA-7-725011: Cipher[8] : EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[9] : EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[10] : EXP-DES-CBC-SHA
%ASA-7-725011: Cipher[11] : EXP-EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[12] : EXP-EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[13] : ECDHE-ECDSA-AES256-SHA384
%ASA-7-725011: Cipher[14] : ECDHE-RSA-AES256-SHA384
%ASA-7-725011: Cipher[15] : AES256-SHA256
%ASA-7-725011: Cipher[16] : DHE-RSA-AES256-SHA256
%ASA-7-725011: Cipher[17] : DHE-DSS-AES256-SHA256
%ASA-7-725011: Cipher[18] : ECDHE-ECDSA-AES256-SHA
%ASA-7-725011: Cipher[19] : ECDHE-RSA-AES256-SHA
%ASA-7-725011: Cipher[20] : AES256-SHA
%ASA-7-725011: Cipher[21] : DHE-RSA-AES256-SHA
%ASA-7-725011: Cipher[22] : DHE-DSS-AES256-SHA
%ASA-7-725011: Cipher[23] : ECDHE-ECDSA-AES128-SHA256
%ASA-7-725011: Cipher[24] : ECDHE-RSA-AES128-SHA256
%ASA-7-725011: Cipher[25] : AES128-SHA256
%ASA-7-725011: Cipher[26] : DHE-RSA-AES128-SHA256
%ASA-7-725011: Cipher[27] : DHE-DSS-AES128-SHA256
%ASA-7-725011: Cipher[28] : ECDHE-ECDSA-AES128-SHA
%ASA-7-725011: Cipher[29] : ECDHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[30] : AES128-SHA
%ASA-7-725011: Cipher[31] : DHE-RSA-AES128-SHA
%ASA-7-725011: Cipher[32] : DHE-DSS-AES128-SHA
%ASA-7-725011: Cipher[33] : ECDHE-ECDSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[34] : ECDHE-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[35] : DES-CBC3-SHA
%ASA-7-725011: Cipher[36] : EDH-RSA-DES-CBC3-SHA
%ASA-7-725011: Cipher[37] : EDH-DSS-DES-CBC3-SHA
%ASA-7-725011: Cipher[38] : ADH-AES256-SHA256
%ASA-7-725011: Cipher[39] : ADH-AES256-SHA
%ASA-7-725011: Cipher[40] : ADH-AES128-SHA256
%ASA-7-725011: Cipher[41] : ADH-AES128-SHA
%ASA-7-725011: Cipher[42] : ADH-DES-CBC3-SHA
%ASA-7-725011: Cipher[43] : DES-CBC-SHA
%ASA-7-725011: Cipher[44] : EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[45] : EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[46] : ADH-DES-CBC-SHA
%ASA-7-725011: Cipher[47] : EXP-DES-CBC-SHA
%ASA-7-725011: Cipher[48] : EXP-EDH-RSA-DES-CBC-SHA
%ASA-7-725011: Cipher[49] : EXP-EDH-DSS-DES-CBC-SHA
%ASA-7-725011: Cipher[50] : EXP-ADH-DES-CBC-SHA
%ASA-7-725011: Cipher[51] : NULL-SHA256
%ASA-7-725011: Cipher[52] : ECDHE-ECDSA-NULL-SHA
%ASA-7-725011: Cipher[53] : ECDHE-RSA-NULL-SHA
%ASA-7-725011: Cipher[54] : NULL-SHA
%ASA-7-725011: Cipher[55] : NULL-MD5
E a conexão agora será bem-sucedida:
%ASA-7-725012: Device chooses cipher AES256-SHA for the SSL session with client asa:10.88.243.57/49949 to 10.122.160.233/443