ID:
SYSCTL_FORWARDINGCategory: Routes and network stack Status in RKNHardering 2.10.0: Active check Role in the verdict: Medium
This page describes the actual implementation in RKNHardering 2.10.0. It distinguishes what can be done without root, what requires root, and where a mitigation only reduces one signal without hiding the VPN as a whole.
/proc/sys/net/ipv4/ip_forward is read as an integer. A nonzero value emits sysctl_forwarding|ip_forward=1; the legacy policy treats it as a medium-confidence review finding.
ip_forward != 0.
Forwarding is common in router, tethering, and root-VPN configurations, but Android may enable it for a hotspot or a system networking mode. It is not an independent VPN indicator.
How the line affects the report: The line does not produce a final verdict on its own, but it sets needsReview=true and adds medium-confidence evidence.
The probe checks only the global IPv4 key, not IPv6 forwarding or per-interface behavior. The value may change when a hotspot is enabled.
This line must be evaluated together with neighboring signals. A clean result from a single API does not simultaneously cover Java Binder, libc, raw netlink/syscalls, procfs/sysfs, local sockets, and server-side indicators.
Disable the hotspot or USB tethering and repeat the test. An ordinary app cannot change this sysctl. If forwarding is required by design, treat the review finding as an accurate description of the system.
Do not set ip_forward=0 blindly; this breaks tethering and router/VPN forwarding. For testing, record the original value and make changes only on a separate device.
adb shell cat /proc/sys/net/ipv4/ip_forward 2>&1
adb shell dumpsys connectivity | grep -i tether -A3 -B2
After any change, force-stop both RKNHardering and the VPN client, start them again, and repeat the full scan. Zygisk, Xposed, and kernel modules usually require a reboot. Compare not only this line but also neighboring signals: a partial hook often creates inconsistencies between APIs.
The probe itself runs with ordinary app permissions and does not request root. The ADB commands below are for orientation only: adb shell runs under a different UID and may see either more or less than the app process. The decisive test is to run the check again after a force-stop.
Disabling forwarding interrupts tethering and some root-based VPN designs.
Restore the saved value, or restart tethering or the device so Android reapplies its normal setting.
Medium. Verified from detectSysctl(); medium kind.
The status of a third-party solution does not automatically carry over to this device. A module developer’s claim is only the initial hypothesis; confirmation requires a reproducible RKNHardering result on the specific Android version, firmware, and kernel.
native_signs_probe.cpp — native probe implementation.NativeSignsChecker.kt — main native/legacy verdict logic.NativeSignalId.kt — complete ID registry.NativeSignalCatalog.kt — category, slug, and line mapping.Related signals: sysctl-rp-filter, route-table.