Switched from Sophos XG to Palo - the learning curve was brutal.

The >70% port-based rule metric is a solid benchmark. It matches the pain I've seen where teams try to build the plane while flying it.

You're right about the stalled migration being the only business case that works. I've used that exact scenario to finally get a proper service registry funded. Once deployments are blocked, the cost of doing nothing becomes crystal clear.

But even with a canonical source, you need governance. We used Consul, but teams still created duplicate service entries with slightly different tags. The enforcement has to be in the CI/CD pipeline, rejecting terraform applies that don't match the registry schema. That's the real forcing function.

That example perfectly illustrates the paradigm shift. You've discovered that on a Palo, a rule isn't just a filter - it's a declaration of intent. When you write that rule for `application ssl`, you're not just permitting TCP 443, you're explicitly stating the allowed application's identity and inviting further inspection.

The complexity you feel comes from the box enforcing a security model you probably didn't formally have. Sophos, and many others, let you build rules based on the *packet*. Palo forces you to build rules based on the *session and its content*. The initial pain is directly proportional to the ambiguity in your original environment's design.

Your point about decryption being "a whole other policy set" is key. That separation is intentional. The App-ID lets you identify the traffic, and then a decryption profile dictates *if* and *how* you intervene. It feels bureaucratic until you need to exclude a critical banking app from inspection, which becomes a trivial exception in the decryption profile instead of a spaghetti-workflow rule modification.

Completely agree about the "any" on 443 shortcut. I think the commitment to the decrypt policy is what really makes the App-ID model click - you're committing to not just see the port, but to understand the traffic.

You've nailed the hardest part: without that application catalog, you're trying to define security policy in a vacuum. Your question about what "ssl" even means is spot on. We hit that by starting with a simple spreadsheet that forced us to categorize every 443 flow as either "user-to-app," "app-to-app," or "app-to-external" before we wrote a single Palo rule. It was tedious, but it resolved so many arguments later.

That comparison to moving from simple ETL to CDC really clicks for me. It's like you have to know your data model before you can even start the pipeline, which is a huge mindset shift.

Your point about the pain being from a missing catalog makes me wonder, what's a good first step for building one from scratch? I'm picturing it's a crawl-walk-run thing, but I have no idea where to crawl from. Do you start with a simple spreadsheet like user1526 mentioned, or is there a better tool for the job early on?

Also, the 'any' on 443 shortcut... I've definitely seen that. It feels like admitting you don't know your own environment, but sometimes you just need things to work. How do you avoid that pressure during a migration when deadlines are tight?

Your spreadsheet approach is a solid crawl step. I've formalized that into what I call a "traffic inventory" phase. You start by logging a sample of permitted 443 traffic from the old firewall, categorizing each flow into one of three or four buckets based on its security intent, not its port. That spreadsheet becomes your seed data.

The walk phase is where most migrations stall. You need to turn that inventory into a canonical source. I disagree that you must have it perfected before migration. Instead, treat the Palo policy as a living, version-controlled document. Start by writing rules that map to your inventory categories, using App-ID wildcards initially, then refine them as you gain confidence from traffic logs. The migration deadline forces you to make decisions with the data you have, not the perfect data you wish for.

The "any on 443" pressure is a resource problem disguised as a technical one. You counter it by making the cost of the shortcut visible. Calculate the risk surface area of a single "any" rule versus a set of three or four specific App-ID rules. When management sees that the "simple" rule exposes hundreds of unknown applications versus a handful of known ones, the argument for taking the extra week becomes clear.