CFSSL

CFSSL is CloudFlare's PKI/TLS swiss army knife. It is both a command line tool and an HTTP API server for signing, verifying, and bundling TLS certificates. It requires Go 1.12+ to build. Note that certain linux distributions have certain algorithms removed (RHEL-based distributions in particular), so the golang from the official repositories will not work. Users of these distributions should install go manually to install CFSSL. You can set the GOOS and GOARCH environment variables to have Go cross compile for alternative platforms; however, cfssl requires cgo, and cgo requires a working compiler toolchain for the target platform. The csr is the client's certificate request. The -ca and -ca-key flags are the CA's certificate and private key, respectively. By default, they are ca.pem and ca_key.pem. The -hostname is a comma separated hostname list that overrides the DNS names and IP address in the certificate SAN extension.