9.2. 处理 API 基础架构问题
如果您在连接到服务器时遇到失败，无论是 API 网关、3scale 或 API，以下故障排除步骤应该是您调用的第一个端口：
9.2.1. 我们可以连接吗？
使用 telnet 检查基本 TCP/IP 连接 telnet api.example.com 443
- 成功
telnet echo-api.3scale.net 80 Trying 52.21.167.109... Connected to tf-lb-i2t5pgt2cfdnbdfh2c6qqoartm-829217110.us-east-1.elb.amazonaws.com. Escape character is '^]'. Connection closed by foreign host.
- 失败
telnet su1.3scale.net 443 Trying 174.129.235.69... telnet: Unable to connect to remote host: Connection timed out
9.2.2. 服务器连接问题
尝试从不同的网络位置、设备和方向连接到同一服务器。例如，如果您的客户端无法访问您的 API，请尝试从应该有权访问 API 的机器（如 API 网关）连接到您的 API。
如果有任何尝试的连接成功，您可以排除实际服务器中的任何问题，并在它们之间的网络上集中进行故障排除，因为这是问题最有可能是的地方。
9.2.3. 这是 DNS 问题吗？
尝试使用 IP 地址而不是其主机名（如 telnet 94.125.104.17 80 而不是 ）连接到服务器
telnet apis.io 80
这将排除 DNS 中的任何问题。
您可以使用 dig 获取服务器的 IP 地址，例如 3scale dig su1.3scale.net 或 dig any su1.3scale.net （如果怀疑主机可能解析到多个 IP 地址）。
NB:有些主机阻止 'dig any'
9.2.4. 这是 SSL 问题吗？
您可以使用 OpenSSL 测试：
保护到主机或 IP 的连接，例如从 shell prompt
openssl s_client -connect su1.3scale.net:443输出：
CONNECTED(00000003) depth=1 C = US, O = GeoTrust Inc., CN = GeoTrust SSL CA - G3 verify error:num=20:unable to get local issuer certificate --- Certificate chain 0 s:/C=ES/ST=Barcelona/L=Barcelona/O=3scale Networks, S.L./OU=IT/CN=*.3scale.net i:/C=US/O=GeoTrust Inc./CN=GeoTrust SSL CA - G3 1 s:/C=US/O=GeoTrust Inc./CN=GeoTrust SSL CA - G3 i:/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA --- Server certificate -----BEGIN CERTIFICATE----- MIIE8zCCA9ugAwIBAgIQcz2Y9JNxH7f2zpOT0DajUjANBgkqhkiG9w0BAQsFADBE ... TRUNCATED ... 3FZigX+OpWLVRjYsr0kZzX+HCerYMwc= -----END CERTIFICATE----- subject=/C=ES/ST=Barcelona/L=Barcelona/O=3scale Networks, S.L./OU=IT/CN=*.3scale.net issuer=/C=US/O=GeoTrust Inc./CN=GeoTrust SSL CA - G3 --- Acceptable client certificate CA names /C=ES/ST=Barcelona/L=Barcelona/O=3scale Networks, S.L./OU=IT/CN=*.3scale.net /C=US/O=GeoTrust Inc./CN=GeoTrust SSL CA - G3 Client Certificate Types: RSA sign, DSA sign, ECDSA sign Requested Signature Algorithms: RSA+SHA512:DSA+SHA512:ECDSA+SHA512:RSA+SHA384:DSA+SHA384:ECDSA+SHA384:RSA+SHA256:DSA+SHA256:ECDSA+SHA256:RSA+SHA224:DSA+SHA224:ECDSA+SHA224:RSA+SHA1:DSA+SHA1:ECDSA+SHA1:RSA+MD5 Shared Requested Signature Algorithms: RSA+SHA512:DSA+SHA512:ECDSA+SHA512:RSA+SHA384:DSA+SHA384:ECDSA+SHA384:RSA+SHA256:DSA+SHA256:ECDSA+SHA256:RSA+SHA224:DSA+SHA224:ECDSA+SHA224:RSA+SHA1:DSA+SHA1:ECDSA+SHA1 Peer signing digest: SHA512 Server Temp Key: ECDH, P-256, 256 bits --- SSL handshake has read 3281 bytes and written 499 bytes --- New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES256-GCM-SHA384 Server public key is 2048 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE No ALPN negotiated SSL-Session: Protocol : TLSv1.2 Cipher : ECDHE-RSA-AES256-GCM-SHA384 Session-ID: A85EFD61D3BFD6C27A979E95E66DA3EC8F2E7B3007C0166A9BCBDA5DCA5477B8 Session-ID-ctx: Master-Key: F7E898F1D996B91D13090AE9D5624FF19DFE645D5DEEE2D595D1B6F79B1875CF935B3A4F6ECCA7A6D5EF852AE3D4108B Key-Arg : None PSK identity: None PSK identity hint: None SRP username: None TLS session ticket lifetime hint: 300 (seconds) TLS session ticket: 0000 - a8 8b 6c ac 9c 3c 60 78-2c 5c 8a de 22 88 06 15 ..l..<`x,\.."... 0010 - eb be 26 6c e6 7b 43 cc-ae 9b c0 27 6c b7 d9 13 ..&l.{C....'l... 0020 - 84 e4 0d d5 f1 ff 4c 08-7a 09 10 17 f3 00 45 2c ......L.z.....E, 0030 - 1b e7 47 0c de dc 32 eb-ca d7 e9 26 33 26 8b 8e ..G...2....&3&.. 0040 - 0a 86 ee f0 a9 f7 ad 8a-f7 b8 7b bc 8c c2 77 7b ..........{...w{ 0050 - ae b7 57 a8 40 1b 75 c8-25 4f eb df b0 2b f6 b7 ..W.@.u.%O...+.. 0060 - 8b 8e fc 93 e4 be d6 60-0f 0f 20 f1 0a f2 cf 46 .......`.. ....F 0070 - b0 e6 a1 e5 31 73 c2 f5-d4 2f 57 d1 b0 8e 51 cc ....1s.../W...Q. 0080 - ff dd 6e 4f 35 e4 2c 12-6c a2 34 26 84 b3 0c 19 ..nO5.,.l.4&.... 0090 - 8a eb 80 e0 4d 45 f8 4a-75 8e a2 06 70 84 de 10 ....ME.Ju...p... Start Time: 1454932598 Timeout : 300 (sec) Verify return code: 20 (unable to get local issuer certificate) ---SSLv3 支持（当前受 3scale 支持）
openssl s_client -ssl3 -connect su.3scale.net:443输出。
CONNECTED(00000003)
140735196860496:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:s3_pkt.c:1456:SSL alert number 40
140735196860496:error:1409E0E5:SSL routines:ssl3_write_bytes:ssl handshake failure:s3_pkt.c:644:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 7 bytes and written 0 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : SSLv3
Cipher : 0000
Session-ID:
Session-ID-ctx:
Master-Key:
Key-Arg : None
PSK identity: None
PSK identity hint: None
SRP username: None
Start Time: 1454932872
Timeout : 7200 (sec)
Verify return code: 0 (ok)
---详情请查看 OpenSSL man page。
