SSL Certificate Validation¶
When establishing a secure connection to a cloud provider endpoint,
Libcloud verifies server SSL certificate. By default, Libcloud searches
paths listed in
libcloud.security.CA_CERTS_PATH variable for the CA
CA_CERTS_PATH contains common paths to CA bundle installations on the
certifipackage on PyPi
opensslpackage on CentOS / Fedora
ca-certificatespackage on Debian / Ubuntu / Arch / Gentoo
ca_root_nssport on FreeBSD
curl-ca-bundleport on Mac OS X
If no valid CA certificate files are found, you will see an error message similar to the one below:
No CA Certificates were found in CA_CERTS_PATH.
The easiest way to resolve this issue is to install certifi Python package from PyPi using pip. This package provides curated collection of Root Certificates based on the Mozilla CA bundle. If this package is installed and available, Libcloud will use CA bundle which is bundled by default.
As the list of trusted CA certificates can and does change, you are also
encouraged to periodically update this package (
pip install --upgrade
certifi or similar).
If for some reason you want to avoid this behavior, you can set
LIBCLOUD_SSL_USE_CERTIFI environment variable to
false. Or even,
better provide a direct path to the CA bundle you want to use using
SSL_CERT_FILE environment variable as shown below.
The CA loading system does not load the Windows Certificate store, since this is not a directory. Windows users should download the following file and place in a directory like %APPDATA%libcloud or somewhere easily accessible. https://raw.githubusercontent.com/bagder/ca-bundle/master/ca-bundle.crt
Then configure this file using one of the 2 methods in Using a custom CA certificate
Acquiring CA Certificates¶
If the above packages are unavailable to you, and you don’t wish to roll your own, the makers of cURL provides an excellent resource, generated from Mozilla: http://curl.haxx.se/docs/caextract.html.
Using a custom CA certificate¶
If you want to use a custom CA certificate file for validating the server certificate, you can do that using two different approaches:
SSL_CERT_FILEenvironment variable to point to your CA file
SSL_CERT_FILE=/home/user/path-to-your-ca-file.crt python my_script.py
libcloud.security.CA_CERTS_PATHvariable in your script to point to your CA file
import libcloud.security libcloud.security.CA_CERTS_PATH = ['/home/user/path-to-your-ca-file.crt'] # Instantiate and work with the driver here...
Adding additional CA certificate to the path¶
If you want to add an additional CA certificate to the
can do this by appending a path to your CA file to the
import libcloud.security libcloud.security.CA_CERTS_PATH.append('/home/user/path-to-your-ca-file.crt') # Instantiate and work with the driver here...
Disabling SSL certificate validation¶
Disabling SSL certificate validations makes you vulnerable to MITM attacks so you are strongly discouraged from doing that. You should only disable it if you are aware of the consequences and you know what you are doing.
To disable SSL certificate validation, set
libcloud.security.VERIFY_SSL_CERT variable to
False at the top of your
script, before instantiating a driver and interacting with other Libcloud code.
import libcloud.security libcloud.security.VERIFY_SSL_CERT = False # Instantiate and work with the driver here...
Changing used SSL / TLS version¶
Linode recently dropped support for TLS v1.0 and it only supports TLS v1.1 and higher. If you are using Linode driver you need to update your code to use TLS v1.1 or TLS v1.2 as shown below.
For compatibility and safety reasons (we also support older Python versions), Libcloud uses TLS v1.0 by default.
If the provier doesn’t support this version or if you want to use a different version because of security reasons (you should always use the highest version which is supported by your system and your provider) you can tell Libcloud to use a different version as shown below.
import ssl import libcloud.security libcloud.security.SSL_VERSION = ssl.PROTOCOL_TLSv1_1 # or libcloud.security.SSL_VERSION = ssl.PROTOCOL_TLSv1_2 # Instantiate and work with the driver here...
Keep in mind that TLS v1.1 and v1.2 is right now only supported in Python >= 3.4 and Python 2.7.9. In addition to that, your system also needs to have a recent version of OpenSSL available.
Another (unsafe and unrecommended) option is to use
ssl.PROTOCOL_SSLv23 constant which will let client know to pick the highest
protocol version which both the client and server support. If this constant is
selected, the client will be selecting between SSL v3.0, TLS v1.0, TLS v1.1 and
Keep in mind that SSL v3.0 is considered broken and unsafe and using this option can result in a downgrade attack so we strongly recommend NOT to use it.