Connection tracking

Modules

conntrack {
    modules {
        ftp
        h323
        nfs
        pptp
        sip
        sqlnet
        tftp
    }
}

Enables conntrack modules. All modules are now disabled by default, while they used to be enabled in previous versions. Enabling the modules ensures backwards compatibility — keeping the previous behavior.

In most cases they can be disabled by removing the block of configuration.

delete system conntrack modules

For some scenarios it is in fact recommended, like in this example: High Availability Walkthrough.