If done at your router's level however, anyone can spot it through an additional firewall + traffic capture.
Merlin, what is your definition of "anyone"?
Would it be the Average Joe that likely makes up 90% of the Asus SOHO wireless routers customer base?
Some more good reads here from the EFF:
"Last year, researchers at ISE found that a staggering 100% of SOHO routers they evaluated were vulnerable to remote attacks. And a recent study found that 80% of Amazon's top 25 best-selling SOHO wireless routers had security issues. Vulnerabilities revealed in these devices ranged from blatantly obvious issues to absurdly inappropriate back doors. The "moon worm" and several other notable exploits of SOHO routers demonstrate that these issues are not only interesting on a theoretical level, but are appearing in the wild and directly affecting consumers. In some cases, the vulnerabilities exploited were the very same that were discovered and reported months earlier—while the router manufacturer had issued a patch, the issues remained in some router models.
https://www.eff.org/deeplinks/2014/07/your-wireless-router-broken-help-us-fix-it-def-con
But there is hope. Only Netgear is currently supported at this time, but we can all help make a difference with donations to get this going to other routers such as our beloved Asus.
"As part of our Open Wireless Movement, we set out to create
router software that would make it easier for people to safely and smartly share part of their wireless network. Protecting hosts, so their security is not compromised because they offer open networks, is one of the goals of the router software we released. However, as research published by Independent Security Evaluators (ISE) and others has shown, almost every popular home router has serious security flaws."