OpenSSL

SSL For Free

openssl -h
openssl x509 -h

View certificate

openssl x509 -in /path/to/file.pem -text -noout

Check validity date

openssl x509 -in /path/to/file.pem -dates -noout

openssl x509 -in /path/to/file.pem -text -noout | grep -i validity -A 2

Domain certificate validity

openssl s_client -host www.example.com -port 443

openssl s_client -connect www.example.com:443 < /dev/null | openssl x509 -noout -dates

Renew certificate

sudo openssl req -new -key /etc/ssl/private/www.example.com.key -out /etc/ssl/certs/www.example.com.csr

Generate certificate

sudo openssl req -new -newkey rsa:2048 -nodes -keyout /etc/ssl/private/www.example.com.key -out /etc/ssl/certs/www.example.com.csr

Decode CSR file

openssl req -text -in /etc/ssl/certs/www.example.com.csr