Re: Local Web Filter Blacklist and Default Block

Your understanding is correct. Just configure white list to allow the specific URLS you want to allow and configure default block to block everything else.

root@srx> show configuration security utm
custom-objects {
url-pattern {
url1 {
value www.google.com;
}
}
custom-url-category {
Google {
value [ url1];
}
}
}
feature-profile {
web-filtering {
url-whitelist Google;
type juniper-local;
juniper-local {
profile Test {
default block;
}
}
}
}

root@srx >

https://www.juniper.net/documentation/en_US/junos/topics/example/utm-web-filtering-local-custom-object-configuring-cli.html