相关疑难解决方法(0)

root@sclrdev:/home/sclr/certs/FreshCerts# curl --ftp-ssl --verbose ftp://{abc}/ -u trup:trup --cacert /etc/ssl/certs/ca-certificates.crt
* About to connect() to {abc} port 21 (#0)
*   Trying {abc}...
* Connected to {abc} ({abc}) port 21 (#0)
< 220-Cerberus FTP Server - Home Edition
< 220-This is the UNLICENSED Home Edition and may be used for home, personal use only
< 220-Welcome to Cerberus FTP Server
< 220 Created by Cerberus, LLC
> AUTH SSL
< 234 Authentication method accepted
* successfully set certificate verify locations:
*   CAfile: …

我正在使用cUrl和PHP向服务器发出请求(用于访问PayPal)

Paypal开发者网站从未提及使用PayPal访问API需要SSL证书,但是我用来请求令牌的代码如下:

$options = array(
                CURLOPT_URL => $url,
                CURLOPT_POST => 1,
                CURLOPT_VERBOSE => 1,
                CURLOPT_POSTFIELDS => $postvals,
                CURLOPT_RETURNTRANSFER => 1,
                CURLOPT_SSLVERSION => 3
);

curl_setopt_array($ch, $options);

$response = curl_exec($ch); 
echo curl_error($ch);

此echo输出以下错误:

SSL certificate problem: unable to get local issuer certificate

我的问题是:

1)如果我只需要获取用户电子邮件,是否需要SSL才能使用PayPal访问？

2)如果我不需要SSL,为什么会出现此错误？

PS:端点如下:https://www.sandbox.paypal.com/webapps/auth/protocol/openidconnect/v1/tokenservice

重新配置 PC 后，我无法正确使用 Docker，因为某些curl 命令由于 SSL/TLS 问题而被拒绝。

仅在一个示例中curl -vfsSL https://apt.releases.hashicorp.com/gpg返回以下错误：

*   Trying 52.222.214.125:443...
* TCP_NODELAY set
* Connected to apt.releases.hashicorp.com (52.222.214.125) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:
*   CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: /etc/ssl/certs
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* TLSv1.3 (IN), TLS handshake, Server hello (2):
* TLSv1.3 (OUT), TLS change cipher, Change cipher spec (1):
* TLSv1.3 (OUT), TLS handshake, Client hello (1):
* …