Tab – SSL

SSL settings can be modified here to configure the details of the HTTPS connection for an individual virtual host.

Example with Server certificate enabled:

SSL Tab

Example with ACME service enabled:

ACME Services enabled

Setting

Description

Enable OCSP stapling

This option enables Online Certificate Status Protocol OCSP stapling.

The Online Certificate Status Protocol (OCSP) was created as an alternative to the Certificate Revocation List (CRL) protocol. Both protocols are used to check whether an SSL Certificate has been revoked.

  • Note:
  • OCSP servers must be in the list of allowed network endpoints. See Section – Allowed Network Endpoints.
  • External OCSP server on the internet may also be reached through an external interface if it is configured accordingly. Depending on the setup, entries in the Submenu – Hosts and Submenu – Routes may be necessary.
  • Validation of client certificates using OCSP is enabled in the client certificate settings, on Certificate Settings.
  • OCSP stapling and ACME services cannot be enabled at the same time.

Certificate type

Server certificate, the SSL/TLS certificate for this virtual host.

  • Server certificate drop-down for certificate selection.
  • Content of SSL server certificate.
  • Content of CA chain.

    • OCSP requires valid chain information for certificate validation - see also Tab – Client Certificates.

  • Content of SSL root CA certificate.

ACME service as configured in Tab – ACME Services (virtual hosts).

  • ACME service drop-down for service selection.
  • E-mail address of the server administrator. This address is used as contact information for the ACME service. Let's Encrypt warns the server administrator if a certificate is about to expire and has not yet been renewed as described in the official Let's Encrypt expiration mail documentation. The address can be set individually for each virtual host.
  • Comment on the selected ACME service (only refreshed on validation).

By using an ACME service, you automatically agree to the terms and conditions of use for the service.

For Let's Encrypt subscriber agreement, see Let's Encrypt policy and legal documentation.

SSL protocol

  • The SSL/TLS version which will be used by this virtual host can be set here.
  • Radio button Default – Airlock Gateway default values will be used. See also Supported SSL/TLS versions.
  • Radio button Custom – set custom values in the SSL protocol field below.

Cipher suite

  • List the ciphers that the client is permitted to negotiate.
  • Radio button Default – default Airlock Gateway cipher suite, optimized for security and backward compatibility with clients.
  • Radio button Custom – set custom values in the cipher suite field below.

We strongly recommend using the default TLS settings of Airlock Gateway in order to mitigate the risk of attacks based on older protocol versions. For example, SSLv3 is not supported by Airlock Gateway 8.0 and higher (configuration activation fails). If you use custom settings, you will also not automatically benefit from optimizations in future Airlock Gateway updates.

Weakening SSL/TLS settings will most likely result in low scores for scanners like ssllabs.com or pentester reporting the security issues associated with old ciphers and protocols.

A list of known attacks on SSL/TLS can be found here: Attacks on TLS and Airlock Gateway Protection Mechanisms.