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IMPORTANT
SNS 3.x versions have reached End of Maintenance since July 1st, 2024.
We recommend that you update your SNS firewalls to a version with maintenance to guarantee the protection of your infrastructure.

# SSL

## “IPS” tab

This screen will allow you to confirm the activation of the SSL protocol through the firewall.

Certain options allow reinforcing this protocol’s security. For example, negotiations of cryptographic algorithms that are deemed weak can be prohibited, or software applications that use SSL to bypass filter policies can be detected (SKYPE, HTTPS proxy, etc).

WARNING

The SSL (Secure Sockets Layer) protocol, which became Transport Layer Security (TLS) in 2001, is supported in version 3 (1996). Sites that use an older version (which may present security flaws) or that do not support the start of a negotiation in TLS will be blocked.

Internet Explorer in version 7 or 8 does not enable by default, support for the protocol TLS 1.0. For security reasons, you are advised to enable TLS 1.0 support via an Active Directory object that defines host configurations (group policy object or GPO).

An ICAP server’s validation of HTTPS requests decrypted by the SSL proxy is not supported.

Automatically detect and inspect the protocol | If this protocol has been enabled, it will automatically be used for discovering corresponding packets in filter rules.

### SSL negotiation

Allow unsupported encryption methods | Select this option if the encryption algorithm that you wish to use is not supported by the SSL protocol.
Allow unencrypted data after an SSL negotiation | This option allows sending data in plaintext after an SSL negotiation. WARNING Allowing data transmission in plaintext poses a security risk.
Authorize signaling cipher (SCSV) | TLS fallback attacks consist of intercepting communications and imposing the weakest cryptographic variant possible. By enabling this option, the firewall will announce a cryptographic pseudo-algorithm that would allow reporting an attempt to launch a fallback attack (RFC 7507).
Encryption levels allowed | The stronger the encryption algorithm used and the more complex the password, the higher the level of security. Example The AES encryption algorithm with a strength of 256 bits, associated with a password of about ten characters made up of letters, numbers and special characters. Three choices of encryption levels can be authorized: Low, medium, high: for example, DES (64 bits), CAST128 (128 bits) and AES. Regardless of the password’s security level, the encryption level will be allowed. Medium and high: Only medium-security and high-security algorithms will be tolerated. Only high: Only strong algorithms and passwords with a high level of security will be tolerated.

### Unencrypted data detection (plaintext traffic)

Detection method | Do not detect: unencrypted data will not be scanned. Inspect all traffic: all packets received will be scanned by the SSL protocol in order to detect plaintext traffic. Sampling (7168 bytes): only the first 7168 bytes of the traffic will be analyzed in order to detect plaintext traffic.

### Support

Disable IPS | When this option is selected, the scan of the SSL protocol will be disabled and traffic will be authorized if the filter policy allows it
Log every SSL query | Enables or disables the logging of SSL requests.

## “Proxy” tab

### Connection

Keep original source IP address | When a request is made by a web client (browser) to the server, the firewall will intercept it and check that the request complies with URL filter rules and then relays the request. If this option is selected, the new request will use the original source IP address of the web client that sent the packet. Otherwise, the firewall’s address will be used.

### Content inspection

Self-signed certificates | These certificates are used internally and signed by your local server. They allow guaranteeing the security of your exchanges and authenticating users, among other functions. This option determines the action to perform when you encounter self-signed certificates: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Continue analysis: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through and is analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
Expired certificates | Expired certificates have validity dates that have lapsed and are therefore not valid. To fix this problem, they must be renewed by a certificate authority WARNING Expired certificates may pose a security risk. After the expiry of a certificate, the CA that issued it will no longer be responsible for it if it is used maliciously. This option determines the action to perform when you encounter expired certificates: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Continue analysis: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through and is analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
Unknown certificates | This option will determine the action to perform when you encounter unknown certificates: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Do not decrypt: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through without being analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
Wrong certificate type | This test validates the certificate’s type. A certificate is deemed compliant if it is used in the context defined by its signature. Therefore, a user certificate used by a server does not comply. This option will determine the action to perform when you encounter non-compliant certificates: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Continue analysis: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through and is analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
Certificate with incorrect FQDN | This option will determine the action to perform when certificates with an invalid domain name are encountered: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Continue analysis: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through and is analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
When the FQDN of the certificate is different from the SSL domain name | This option will determine the action to perform when you encounter certificates with domain names (FQDN) that are different from the expected SSL domain: Delegate to user: this action raises a security alert in the client's web browser. The client will then decide whether to continue the connection to the server concerned. An alarm will be generated and the client's action will be recorded in the logs l_alarm file. Continue analysis: these certificates are accepted without generating any security alerts in the client's web browser. Traffic goes through and is analyzed by the intrusion prevention engine. Block: the firewall rejects these certificates and matching traffic is blocked.
Allow IP addresses in SSL domain names | This option allows or denies access to a site based on its IP addresses instead of its SSL domain name.

### Support

If decryption fails | This option will determine the action to perform when decryption fails: you can choose to Block traffic or Pass without decrypting. Traffic will not be inspected if the second option is selected.
If classification of certificate fails | The choice is either Pass without decrypting or Block. If a certificate has not been listed in a certificate category, this action will determine whether the traffic will be authorized.