openstack 命令行nova list执行失败，提示认证不成功

【问题现象】
2014-09-03 19:18:25.520 22053 WARNING keystoneclient.middleware.auth_token [-] Verify error: Command 'openssl' returned non-zero exit status 4
2014-09-03 19:18:25.522 22053 WARNING keystoneclient.middleware.auth_token [-] Authorization failed for token
2014-09-03 19:18:25.523 22053 INFO keystoneclient.middleware.auth_token [-] Invalid user token - rejecting request
2014-09-03 19:18:25.524 22053 INFO nova.osapi_compute.wsgi.server [-] 172.16.25.199 “GET /v2/935c7c53786443929d1738b6d9577111/servers/detail HTTP/1.1” status: 401 len: 196 time: 0.2928760
2014-09-03 19:18:25.757 22053 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): 172.16.25.199
2014-09-03 19:18:25.820 22053 WARNING keystoneclient.middleware.auth_token [-] Verify error: Command 'openssl' returned non-zero exit status 4
2014-09-03 19:18:25.821 22053 WARNING keystoneclient.middleware.auth_token [-] Authorization failed for token
2014-09-03 19:18:25.822 22053 INFO keystoneclient.middleware.auth_token [-] Invalid user token - rejecting request
2014-09-03 19:18:25.823 22053 INFO nova.osapi_compute.wsgi.server [-] 172.16.25.199 “GET /v2/935c7c53786443929d1738b6d9577111/servers/detail HTTP/1.1” status: 401 len: 196 time: 0.0682800

【解决过程】
查看 curl http://localhost:35357/v2.0/certificates/signing
Certificate:

Data:
    Version: 3 (0x2)
    Serial Number: 1 (0x1)
Signature Algorithm: sha1WithRSAEncryption
    Issuer: C=US, ST=Unset, L=Unset, O=Unset, CN=www.example.com
    Validity
        ******Not Before: Sep  3 13:12:59 2014 GMT
        Not After : Aug 31 13:12:59 2024 GMT******
    Subject: C=US, ST=Unset, O=Unset, CN=www.example.com
    Subject Public Key Info:
        Public Key Algorithm: rsaEncryption

发现系统时间不在有效期内

【解决方法】
调整i系统时间至有效期内