Hey everyone, I've been learning how to manage a small fleet of SRX firewalls at work and found it tricky to keep track of all the NAT rules across different devices. I wanted a quick way to audit them.
So I wrote a simple Python script that uses Netmiko to connect to multiple SRX devices, pulls the NAT configuration, and outputs a consolidated report. It's been super helpful for me to spot duplicates or missing rules. It's pretty basic right now, but maybe others starting out could find it useful or suggest improvements? 😊
It basically just runs `show security nat source rule all` and `show security nat static rule all` on each device and combines the output into a CSV. Let me know if something like this would be helpful and I can share the code!
Consolidating NAT rules into a single report is a solid step for any multi-device setup. While CSV output is practical for a quick review, you'll want to consider how you're handling rule context and hierarchy. Pulling just the raw rules might miss related address books or security policies that could make a rule inactive.
You should also think about adding basic validation. For example, flagging rules with overlapping address pools or checking for rules that reference undefined NAT pools. That's where these scripts go from being a simple dump to an actual audit tool.
I'd be interested in seeing how you handle device authentication and error logging. Sharing the code could get you some good feedback on those points.
—AF
Totally agree on the jump from dump to audit, but "basic validation" can be a rabbit hole. Overlap checking sounds great until you hit rule-sets using dynamic addresses or overlapping pools by design for failover.
Also, pulling address books and security policies for context is the right move in theory. In practice, you're now parsing half the config and the script's a mini compliance engine. Good luck getting that approved as a "quick audit" tool 😉
Curious how user1311 handles hierarchy on the SRX specifically - rule-sets vs. rules? That's where most homemade parsers fall down.
Trust but verify.
You're absolutely right about that rabbit hole. I started adding overlap checks and immediately had to add a manual exception list for our DMZ failover design. That's when I realized I was building a config parser, not an audit script.
For the rule-sets vs. rules hierarchy, I'm taking the easy way out for now. I just grab the rule-set name as a column in the CSV. The real pain point, as you hinted, is that a rule's "context" spans security policies, address books, and applications. Without that, you can't tell if a rule is even active.
Maybe the sweet spot is to keep the dump simple, but add a simple check for undefined NAT pool references? That's a single, objective flag you can add without parsing the whole world.
Cloud cost nerd. No, I don't use Reserved Instances.