On Tue, Oct 8, 2019 at 6:51 AM Rich Kulawiec <rsk@gsp.org> wrote:
On Tue, Oct 08, 2019 at 01:35:16PM +0100, Mike Meredith via NANOG wrote:
You've ignored step 1 - identifying critical information that needs protecting. It makes sense to protect information that needs protecting and don't lose sleep over information that doesn't need protecting. Not many of us are planning an invasion of a Nazi-infected Europe any time soon.
We are heading toward a restatement of Kerckhoff's principle/Shannon's maxim, the latter of which can be paraphrased as "design systems assuming that your adversary will know as much about them as you do".
They aren't mutually exclusive concepts. A strong security architecture has multiple layers an adversary must penetrate. No layer has to be sufficient on its own, it just has to reduce vulnerability more than it increases cost. Limiting the server banner so it doesn't tell an adversary the exact OS-specific binary you're using has a near-zero cost and forces an adversary to expend more effort searching for a vulnerability. It doesn't magically protect you from hacking on its own. As you say, your security must not be breached just because the adversary figures out what version you're running. But viewed as one layer in an overall plan, limiting that information enhances your security at negligible cost. That's security smart. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/