The following table describes the settings you can use
to control decrypted inbound and outbound SSH traffic. These settings
allow you to limit or block SSH tunneled traffic based on criteria
including the use of unsupported algorithms, the detection of SSH
errors, or the availability of resources to process SSH Proxy decryption.
SSH Proxy Tab Settings
Unsupported Mode Checks
these options to control sessions if unsupported modes are detected
in SSH traffic. Supported SSH version is SSH version 2.
Block sessions with unsupported versions
Terminate sessions if the “client hello”
message is not supported by PAN-OS.
block sessions with unsupported versions to prevent access to sites with
weak protocols. On the
SSL Protocol Settings
set the minimum Protocol Version to TLSv1.2 to block sites with
weak protocol versions. If a site you need to access for business
purposes uses a weaker protocol, create a separate Decryption profile
that allows the weaker protocol and specify it in a Decryption policy
rule that applies only to the sites for which you must allow the
Block sessions with unsupported algorithms
Terminate sessions if the algorithm specified
by the client or server is not supported by PAN-OS.
Always block sessions with unsupported
algorithms to prevent access to sites that use weak algorithms.
actions to take if SSH application errors occur and if system resources
are not available.
Block sessions on SSH errors
Terminate sessions if SSH errors occur.
Block sessions if resources not available
Terminate sessions if system resources are
not available to process decryption.
Whether to block sessions
when resources aren’t available is a tradeoff between tighter security and
a better user experience. If you don’t block sessions when resources
aren’t available, the firewall won’t be able to decrypt traffic
that you want to decrypt when resources are impacted. However, blocking sessions
when resources aren’t available may affect the user experience because
sites that are normally reachable may become temporarily unreachable.