curl: (60) Peer's Certificate issuer is not recognized

After our company implements stricter rules, I can't install docker in my vagrant properly. I have been solving this issue for about a week and its hard to point out the correct solution until I found from stackoverflow.

add this in vagrant file
config.vm.box_download_ca_cert = "./Fortinet_CA_SSL.cer"

Finally fixed it. Post the answer here as reference.

• Export company trusted root certificate with .cer extension. Somthing naming external root certificate
• Convert the ca file to .pem file using openssl x509 -in xxx.cer -inform der -outform pem -out xxx.pem

Then on the centos 7 os:

• Install the ca-certificates package: yum install ca-certificates
• Enable the dynamic CA configuration feature: update-ca-trust force-enable
• Add the exported pem files to /etc/pki/ca-trust/source/anchors/
• Use command: update-ca-trust extract

https://stackoverflow.com/questions/47676980/curl-60-peers-certificate-issuer-is-not-recognized