使用open_ssl和curl验证服务器证书

我有一个嵌入式设备（运行mbedTLS），它只能包含数量非常有限的服务器证书，我想用curl验证我放在设备上的PEM文件。 我正在使用icanhazip.com（IPv6）进行验证。 要创建PEM文件，我使用openSSL：

openssl s_client -connect icanhazip.com:443 -showcerts

并将证书部分存储在icanhazip_com.pem中，并尝试使用curl验证：

curl --verbose --cacert icanhazip_com.pem https://icanhazip.com

但我有一个错误：

$ curl --verbose --cacert icanhazip_com.pem https://icanhazip.com
* Rebuilt URL to: https://icanhazip.com/
* timeout on name lookup is not supported
*   Trying 2607:ff68:116:f33d::13...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0* Connected to icanhazip.com (2607:ff68:116:f33d::13) port 443 (#0)
* ALPN, offering http/1.1
* Cipher selection: ALL:!EXPORT:!EXPORT40:!EXPORT56:!aNULL:!LOW:!RC4:@STRENGTH
* successfully set certificate verify locations:
*   CAfile: icanhazip_com.pem
  CApath: none
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
} [5 bytes data]
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
} [512 bytes data]
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0* TLSv1.2 (IN), TLS handshake, Server hello (2):
{ [108 bytes data]
* TLSv1.2 (IN), TLS handshake, Certificate (11):
{ [2792 bytes data]
* TLSv1.2 (OUT), TLS alert, Server hello (2):
} [2 bytes data]
* SSL certificate problem: unable to get issuer certificate
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
* Closing connection 0
} [5 bytes data]
* TLSv1.2 (OUT), TLS alert, Client hello (1):
} [2 bytes data]
curl: (60) SSL certificate problem: unable to get issuer certificate
More details here: http://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle"
 of Certificate Authority (CA) public keys (CA certs). If the default
 bundle file isn't adequate, you can specify an alternate file
 using the --cacert option.
If this HTTPS server uses a certificate signed by a CA represented in
 the bundle, the certificate verification probably failed due to a
 problem with the certificate (it might be expired, or the name might
 not match the domain name in the URL).
If you'd like to turn off curl's verification of the certificate, use
 the -k (or --insecure) option.

---

您存储了哪个证书部件？我怀疑您没有将正确的证书放入您的文件

icanhazip\u com.pem

。您必须放入CA证书，即发卡机构提供的证书（即，让我们加密）

从

openssl s_client

的输出来看，这是第二个，而不是第一个：

Certificate chain
0 s:/CN=icanhazip.com
i:/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
-----BEGIN CERTIFICATE-----
        ...
(icanhazip.com certificate)
        ...
-----END CERTIFICATE-----
1 s:/C=US/O=Let's Encrypt/CN=Let's Encrypt Authority X3
i:/O=Digital Signature Trust Co./CN=DST Root CA X3
-----BEGIN CERTIFICATE-----
        ...
(Let's Encrypt CA certificate)
        ...
-----END CERTIFICATE-----

---

您也可以选择将

openssl s_client

命令生成的所有证书存储在一个捆绑文件中（

openssl s_client-connect icanhazip.com:443-showcerts>icanhazip_com.pem

），但如果磁盘空间有限，这并不理想。

。。。如果我从Let's Encrypt网站手动下载证书，效果会很好。如果您只将Let's Encrypt证书（而不是两者）放在icanhazip_com.pem中会怎么样？也许您的curl版本不支持证书捆绑包？我只尝试了第二个证书。还是一样的错误。