Just spent half my day figuring this out on our new NSa 2700. Wanted a proper DMZ for a test web server, but kept locking myself out or creating weird routing loops. The wizard was… not helpful.
Finally got it working. The key was in the Address Objects and Access Rules, not just the Zone settings. Had to make sure the DMZ zone's "Default Gateway" was set to the firewall's DMZ interface IP, and the access rule from LAN to DMZ needed to be *above* the default "Allow Any" rule. Learned the hard way that order matters a ton.
Still learning…
Trying to figure it out.
The rule order thing gets me every time. Had a similar lockout on an older model because of that.
So the DMZ's default gateway has to point back to the firewall interface itself? Not to our main internal router? That's probably where I'd have messed up.
Yeah, that's the classic pitfall. The DMZ zone's gateway is the firewall itself. If you pointed it to your internal router, you'd be sending DMZ traffic back into your LAN, bypassing the firewall's policy. Kind of defeats the purpose of having a DMZ at all.
Your vendor is not your friend.
Ah, the classic "firewall as gateway" dogma. It's treated as scripture until you run into a real-world throughput bottleneck because every packet between your DMZ app server and its back-end database on the LAN has to get inspected twice by the same box. Suddenly that "bypass" starts looking like a necessary performance hack.
Seen it cause a cascading failure when the firewall CPU spiked. The DMZ servers couldn't talk to the LAN servers they depended on, the app timed out, and the whole thing looked like a DDoS. So yeah, it defeats the *security* purpose, but sometimes you're just trying to keep the lights on while management refuses to buy adequate hardware.
Test your rollback first
Ah, a rare voice of practical heresy. I love it.
You're absolutely right about the dogma, but calling it a "performance hack" is generous. It's more like deciding which limb to amputate because you can't afford a tourniquet. The double-inspection tax is brutal on stateful firewalls, especially with chatty protocols.
I've seen teams solve this by putting the database *in* the DMZ, which is... a choice. Or worse, they'll open a pinhole directly from the internet-facing load balancer to the LAN database because "it's just health checks." Suddenly your sacred DMZ is just a fancy VLAN with extra steps.
The real joke is that we buy these expensive all-in-one appliances and then architect around their limitations, creating the very spaghetti we were supposed to prevent. Maybe the true DMZ was the friends we bypassed along the way.
🤷
> The real joke is that we buy these expensive all-in-one appliances and then architect around their limitations
This is exactly why I push for simpler, layered designs whenever possible. You can't outsmart physics - a single box trying to be a router, stateful firewall, and IPS is going to have a ceiling. It forces those terrible trade-offs between security and uptime.
The "database in the DMZ" pattern is a perfect example of a fix that becomes a permanent liability. I once inherited a system where they'd done that, then "temporarily" enabled direct SQL access from the app servers for debugging. That was five years ago. The fix is now a core dependency.
Latency is the enemy, but consistency is the goal.