连接到gateway.sandbox.push.apple.com时出现“验证错误：num =

Question

我正在尝试运行在iOS 6教程：第1/2部分的Apple Push Notification Services中找到的Ray Wenderlich教程。我在本地目录中创建了AppID和SSL证书以及密钥和PEM文件。之后，我进入测试证书是否有效的步骤，并从此本地目录调用了以下命令：$ openssl s_client -connect gateway.sandbox.push.apple.com:2195 -cert PushChatCert.pem -key PushChatKey.pem这产生了很多输出。在输出的中间是以下内容：verify error:num=20:unable to get local issuer certificateverify return:0这是错误，还是测试错误？如果是错误，将是什么原因或您将建议如何解决？这是完整的输出（减去证书数据）：Enter pass phrase for PushChatKey.pem:    CONNECTED(00000003)depth=1 /C=US/O=Entrust, Inc./OU=www.entrust.net/rpa is incorporated by reference/OU=(c) 2009 Entrust, Inc./CN=Entrust Certification Authority - L1Cverify error:num=20:unable to get local issuer certificateverify return:0---Certificate chain 0 s:/C=US/ST=California/L=Cupertino/O=Apple Inc./OU=iTMS Engineering/CN=gateway.sandbox.push.apple.com   i:/C=US/O=Entrust, Inc./OU=www.entrust.net/rpa is incorporated by reference/OU=(c) 2009 Entrust, Inc./CN=Entrust Certification Authority - L1C 1 s:/C=US/O=Entrust, Inc./OU=www.entrust.net/rpa is incorporated by reference/OU=(c) 2009 Entrust, Inc./CN=Entrust Certification Authority - L1C   i:/O=Entrust.net/OU=www.entrust.net/CPS_2048 incorp. by ref. (limits liab.)/OU=(c) 1999 Entrust.net Limited/CN=Entrust.net Certification Authority (2048)---Server certificate-----BEGIN CERTIFICATE-----<Long string of data removed>-----END CERTIFICATE-----subject=/C=US/ST=California/L=Cupertino/O=Apple Inc./OU=iTMS Engineering/CN=gateway.sandbox.push.apple.comissuer=/C=US/O=Entrust, Inc./OU=www.entrust.net/rpa is incorporated by reference/OU=(c) 2009 Entrust, Inc./CN=Entrust Certification Authority - L1C---No client certificate CA names sent---SSL handshake has read 2731 bytes and written 2215 bytes---New, TLSv1/SSLv3, Cipher is AES256-SHAServer public key is 2048 bitSecure Renegotiation IS supportedCompression: NONEExpansion: NONE该教程继续说：“如果连接成功，您应该可以输入几个字符。按Enter键时，服务器应该断开连接。” 我能够做到这一点，并且服务器已断开连接。但是本教程继续说，您可能必须查看输出以发现错误。因此，这个问题的原因。