I've noticed that our link checker, which uses cURL, fails more and more often to validate SSL certificates. I'm trying to get to the bottom of this.
https://www.bgetem.de/, for instance, opens just fine on every browser (IE 11, Firefox, Opera, Chrome) on my Windows 7 machine, but cURL (and wget) on my CentOS 6 and Ubuntu 16.04 cannot validate the certificate.
Here is cURL's verbose output from CentOS (Version
curl 7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.27.1 zlib/1.2.3 libidn/1.18 libssh2/1.4.2)
* About to connect() to www.bgetem.de port 443 (#0) * Trying 22.214.171.124... connected * Connected to www.bgetem.de (126.96.36.199) port 443 (#0) * Initializing NSS with certpath: sql:/etc/pki/nssdb * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * Peer's certificate issuer is not recognized: 'CN=COMODO RSA Domain Validation Secure Server CA,O=COMODO CA Limited,L=Salford,ST=Greater Manchester,C=GB' * NSS error -8179 * Closing connection #0 * Peer certificate cannot be authenticated with known CA certificates
And Ubuntu (Version
curl 7.47.0 (x86_64-pc-linux-gnu) libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32 librtmp/2.3):
* found 173 certificates in /etc/ssl/certs/ca-certificates.crt * found 695 certificates in /etc/ssl/certs * ALPN, offering http/1.1 * SSL connection using TLS1.2 / ECDHE_RSA_AES_256_GCM_SHA384 * server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none * Closing connection 0 curl: (60) server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none
Any idea what the problem is and how I can fix it?