Just a quick tip on setting up stunnel in transparent proxy mode (ie. target service sees original source IP address) pointing at services running on localhost. (mostly based on sslh documentation)

Use the following iptables/sysctl rules:

#!/bin/bash

set -e

# Set route_localnet = 1 on all interfaces so that ssl …

I'll keep it updated with my notes when playing with buildroot.

How to properly store project-specific, non-mainline configs and such?

Use external tree.

How to add custom make target (eg. felboot)?

Put it in external.mk. Common variables, such as $(BINARIES_DIR) are available there.

How to handle image configuration/customization …