有効な SSL 証明書を持つサイトで curl コマンドを実行すると、エラー"curl: (60) Peer certificate cannot be authenticated with known CA certificates" が発生する

Issue

• 有効な SSL 証明書を持つサイトで curl コマンドを実行すると、エラー"curl: (60) Peer certificate cannot be authenticated with known CA certificates" が発生します。

  [root@example.com ~]# curl -v https://example.com
  * About to connect() to example.com port 443 (#0)
  *   Trying 192.168.0.254... connected
  * Connected to example.com (192.168.0.254) port 443 (#0)
  * Initializing NSS with certpath: sql:/etc/pki/nssdb
  *   CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
  * Certificate is signed by an untrusted issuer: 'CN=Go Daddy Secure Certificate Authority - G2,OU=http://www.example.com/repository/,O="example.com, Inc.",L=Scottsdale,ST=Arizona,C=US'
  * NSS error -8172
  * Closing connection #0
  * Peer certificate cannot be authenticated with known CA certificates
  curl: (60) Peer certificate cannot be authenticated with known CA certificates
  More details here: http://www.example.com/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.
  

• 証明書を手動で更新すると、エラーは発生しません。

  [root@example.com certs]# curl http://www.example.com/ca/cacert.pem -o /etc/pki/tls/certs/ca-bundle.crt
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
  Dload  Upload   Total   Spent    Left  Speed
  100  223k  100  223k    0     0   222k      0  0:00:01  0:00:01 --:--:--  265k
  [root@example.com certs]# curl -v https://example.com
  * About to connect() to example.com port 443 (#0)
  *   Trying 192.168.0.254... connected
  * Connected to example.com (192.168.0.254) port 443 (#0)
  * Initializing NSS with certpath: sql:/etc/pki/nssdb
  *   CAfile: /etc/pki/tls/certs/ca-bundle.crt
  CApath: none
  * SSL connection using SSL_RSA_WITH_RC4_128_SHA
  * Server certificate:
  *       subject: CN=www.example.com,OU=Domain Control Validated
  *       start date: Sep 06 18:00:03 2013 GMT
  *       expire date: Sep 06 18:00:03 2014 GMT
  *       common name: www.example.com
  *       issuer: CN=Secure Certificate Authority - G2,OU=http://www.example.com/repository/,O="example.com, Inc.",L=Scottsdale,ST=Arizona,C=US
  > GET / HTTP/1.1
  > User-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.14.0.0 zlib/1.2.3 libidn/1.18 libssh2/1.4.2
  > Host: example.com
  > Accept: */*
  > 
  < HTTP/1.1 200 OK
  < Date: Mon, 16 Sep 2013 19:49:10 GMT
  < Server: Apache
  < X-Powered-By: PHP/5.3.3
  < Content-Length: 0
  < Connection: close
  < Content-Type: text/html; charset=UTF-8
  < 
  * Closing connection #0