:experimental:
ifdef::env-github[]
:icons:
:tip-caption: :bulb:
:note-caption: :information_source:
:important-caption: :heavy_exclamation_mark:
:caution-caption: :fire:
:warning-caption: :warning:
endif::[]

== About
[.lead]
This bypass method & tutorial compared to PDANet, FoxFi, NetShare, EasyTether, Wi-Fi Tether Router, and sshuttle tunneling:

. Reliable with little to no speed reduction.

. Plug and play, other devices don't need to install apps to have internet.

. Bypasses service specific throttling such as limited video quality on YouTube or other streaming services, and censorship.
** Other devices have to install an app for this goal, it's unavoidable.

This guide is tested from an unlocked US https://swappa.com/listings/google-pixel-4a-5g/unlocked[Pixel 4a 5G], it can be had for ~$110.


== Preparation
. https://topjohnwu.github.io/Magisk/[Install Magisk]; read "Getting Started", then "Patching Images".

. Install the following apps:

* A https://f-droid.org/repo/jackpal.androidterm_72.apk[terminal emulator]; for that app make sure to allow all the permissions it asked for.

* https://apkpure.com/network-signal-guru/com.qtrun.QuickTest[Network Signal Guru] for its radio band locking to maintain and increase network speeds.

* https://github.com/AdAway/AdAway/releases[AdAway] to block Network Signal Guru's advertising.
** AdAway requires you to enable "Systemless Hosts" in Magisk's settings.

* https://apkpure.com/netmonster/cz.mroczis.netmonster[NetMonster] for its network monitoring. Without it, you are practically blind to what LTE or 5G bands are used, and what the various signal strengths are; this is very useful information.


=== Testing mangling support
. Open a terminal emulator.
. `$ su`
. `# iptables -t mangle -A POSTROUTING -o null -j TTL --ttl-inc 1; ip6tables -t mangle -A POSTROUTING -o null -j HL --hl-inc 1`
** No output is good/desired. If this is the case, link:#skip-ahead[skip ahead] to blocking Android snitching, and spoofing TTL & HL.

=== Downloading a suitable custom kernel
NOTE: The listed kernels include the BBR or BBRv2 TCP congestion control algorithm to https://web.archive.org/web/20220313173158/http://web.archive.org/screenshot/https://docs.google.com/spreadsheets/d/1I1NcVVbuC7aq4nGalYxMNz9pgS9OLKcFHssIBlj9xXI[help maintain speeds over bad network conditions].

|===
| 1. momojuro's https://forum.xda-developers.com/search/member?user_id=5670369&content=thread[fsociety tribute]; recommended for the Pixel 4A (5G) and Pixel 5.
| 2. Freak07's https://forum.xda-developers.com/search/member?user_id=3428502&content=thread[Kirisakura]; recommended for the Pixel 6.
| 3. kdrag0n's https://forum.xda-developers.com/search/member?user_id=7291478&content=thread[Proton].
|===

TIP: Not for your device? +
Use these search terms on the https://forum.xda-developers.com/search/[XDA Forums] to find other kernels with "xt_HL.ko" support: +
`TTL spoofing`, `TTL target`, `IPtables TTL`, `TTL/HL target`, `TTL module`.


=== Installing a custom kernel
. Download the https://github.com/Magisk-Modules-Alt-Repo/BuiltIn-BusyBox/releases[Built-In BusyBox] Magisk module.
. Open Magisk -> Modules -> Install from storage -> Select the module ZIP that was downloaded.
. Reboot.
. Install https://github.com/libxzr/HorizonKernelFlasher/releases[Horizon Kernel Flasher], open it, then point it to the ZIP containing the custom kernel.


== [[skip-ahead]]1. Blocking Android snitching, and spoofing TTL & HL
. Download our https://github.com/felikcat/unlimited-hotspot/releases/download/v5/unlimited-hotspot-v5.zip[Unlimited Hotspot] Magisk module.
. Open Magisk -> Modules -> Install from storage -> Select the "unlimited-hotspot-v5.zip" that was downloaded.
. Reboot.


[.lead] 
For routers to also be plug and play, additional steps are required:

.Asuswrt-Merlin
[%collapsible]
====
. `Advanced Settings - WAN` -> disable `Extend the TTL value` and `Spoof LAN TTL value`.
. `Advanced Settings - Administration`
** `Enable JFFS custom scripts and configs` -> "Yes"
** `Enable SSH` -> "LAN only"
. Replace the LAN IP and login name if needed: `$ ssh 192.168.50.1 -l asus`
** Use other SSH clients if preferred, such as MobaXterm or Termius.
. `# nano /jffs/scripts/wan-event`

[source, shell]
----
#!/bin/sh
# shellcheck disable=SC2068
Say() {
  printf '%s%s' "$$" "$@" | logger -st "($(basename "$0"))"
}
WAN_IF=$1
WAN_STATE=$2

# Call appropriate script based on script_type
SERVICE_SCRIPT_NAME="wan${WAN_IF}-${WAN_STATE}"
SERVICE_SCRIPT_LOG="/tmp/WAN${WAN_IF}_state"

# Execute and log script state
if [ -f "/jffs/scripts/${SERVICE_SCRIPT_NAME}" ]; then
  Say "     Script executing.. for wan-event: $SERVICE_SCRIPT_NAME"
  echo "$SERVICE_SCRIPT_NAME" >"$SERVICE_SCRIPT_LOG"
  sh /jffs/scripts/"${SERVICE_SCRIPT_NAME}" "$@"
else
  Say "     Script not defined for wan-event: $SERVICE_SCRIPT_NAME"
fi

##@Insert##
----

`# nano /jffs/scripts/wan0-connected`
[source, shell]
----
#!/bin/sh

# HACK: Not sure what to check for exactly; do it too early and the TTL & HL won't get set.
sleep 5s; modprobe xt_HL; wait

# Removes these iptables entries if present; only removes once, so if the same entry is present twice (script assumes this never happens), it would need to be removed twice.
iptables -t mangle -D PREROUTING -i usb+ -j TTL --ttl-inc 2
iptables -t mangle -D POSTROUTING -o usb+ -j TTL --ttl-inc 2
ip6tables -t mangle -D PREROUTING ! -p icmpv6 -i usb+ -j HL --hl-inc 2
ip6tables -t mangle -D POSTROUTING ! -p icmpv6 -o usb+ -j HL --hl-inc 2

# TTL & HL hotspot detection bypass.
## Increments the TTL & HL by 2 (1 for the router, 1 for the devices connected to the router).
iptables -t mangle -A PREROUTING -i usb+ -j TTL --ttl-inc 2
iptables -t mangle -I POSTROUTING -o usb+ -j TTL --ttl-inc 2
ip6tables -t mangle -A PREROUTING ! -p icmpv6 -i usb+ -j HL --hl-inc 2
ip6tables -t mangle -I POSTROUTING ! -p icmpv6 -o usb+ -j HL --hl-inc 2
----
TIP: Set permissions correctly to avoid this: `custom_script: Found wan-event, but script is not set executable!` +
1. `# chmod a+rx /jffs/scripts/*` +
2. `# reboot`

___
====


.GoldenOrb or OpenWrt via LuCI
[%collapsible]
====
. GoldenOrb specific: `Network` -> `Firewall` -> `Custom TTL Settings`
** Ensure its option is disabled.
. `Network` -> `Firewall` -> `Custom Rules`
[source, shell]
----
# Removes these iptables entries if present; only removes once, so if the same entry is present twice (script assumes this never happens), it would need to be removed twice.
iptables -t mangle -D PREROUTING -i usb+ -j TTL --ttl-inc 2
iptables -t mangle -D POSTROUTING -o usb+ -j TTL --ttl-inc 2
ip6tables -t mangle -D PREROUTING ! -p icmpv6 -i usb+ -j HL --hl-inc 2
ip6tables -t mangle -D POSTROUTING ! -p icmpv6 -o usb+ -j HL --hl-inc 2

# TTL & HL hotspot detection bypass.
## Increments the TTL & HL by 2 (1 for the router, 1 for the devices connected to the router).
iptables -t mangle -A PREROUTING -i usb+ -j TTL --ttl-inc 2
iptables -t mangle -I POSTROUTING -o usb+ -j TTL --ttl-inc 2
ip6tables -t mangle -A PREROUTING ! -p icmpv6 -i usb+ -j HL --hl-inc 2
ip6tables -t mangle -I POSTROUTING ! -p icmpv6 -o usb+ -j HL --hl-inc 2
----

___
====


== 2. Confirm the tethering is un-throttled
TIP: After enabling USB tethering, enable "Data Saver". This tells Android to restrict data to USB tethering and what app is at the forefront only.

. Use https://fast.com[Netflix's Speedtest], then compare that result to https://www.waveform.com/tools/bufferbloat[Waveform's Bufferbloat Test]. +
This tests for throttling of streaming servers (Netflix), various forms of data fingerprinting, and tethering/hotspot detections.
. If Netflix is throttled, use the https://github.com/krlvm/PowerTunnel[PowerTunnel] app on the client/tethered to device with its LibertyTunnel addon enabled, and test again.


== 3. Getting better internet speeds
. Search for "Roaming" in the Settings app, then disable Roaming.
** Roaming to a different telecom usually means unavoidable throttling.
*** For example, T-Mobile USA's agreement with AT&T allow the usage of AT&T towers, but only up to 250kbps download & upload speeds is allowed while roaming on AT&T's network.
. Use Network Signal Guru to set the allowed LTE bands to only the "LTE 4x4 Bands" listed on https://cacombos.com/device/G025E[cacombos.com] for your device.


== This guide doesn't work, or goes from fast to inexplicably slow
[.lead]
Using a VPN is likely the missing puzzle piece. +
VPNs bypass DPI firewalls, they will not increase privacy.


.Least shady free VPNs; try before any paid VPNs.
[%collapsible]
====

. https://protonvpn.com/free-vpn/[ProtonVPN Free]

. https://cryptostorm.is/cryptofree[Cryptofree]
** Using their free WireGuard server is recommended.

. https://cloudflarewarp.com/[Cloudflare WARP] (never torrent on this). +
You can get the https://github.com/TheCaduceus/WARP-UNLIMITED-ADVANCED[paid WARP+ for free].

___
====


.Recommendations and requirements for a good paid VPN provider.
[%collapsible]
====

*The recommendations*

* United States citizens: https://www.privateinternetaccess.com/vpn-server[Private Internet Access]. Has a server in every single US state, and an optional dedicated IP addon if streaming services (Netflix, Hulu, Amazon Prime, etc.) must always work.
* The fastest, but with a limited selection of servers for the United States: https://hide.me/en/network[hide.me].
* Strong emphasis on ethics: https://mullvad.net/en/servers[Mullvad], https://www.cryptostorm.is/uptime[Cryptostorm], https://airvpn.org/status/[AirVPN].


*The requirements*

. Network locking in their VPN software is reliable; very important to stay under the telecom's radar regarding "OS fingerprinting".

. Show which servers are geolocated/virtual (fake location) servers, or have none.

. Addon available (or included) for a dedicated/static/streaming IP, to get around streaming service blocks, and other websites using anti-VPN services such as https://blocked.com.

. P2P/ http://www.bittorrent.org/introduction.html[BitTorrent protocol] isn't blocked on all servers.
** If all servers have this protocol unblocked, it will narrow down the amount of hosting services that VPN provider can use. +
This means higher ping/latency for some ISPs/telecoms; low latency is important for online gaming and video conferencing, among others.

. SOCKS5 and HTTPS/SSL proxies provided.
** Some VPNs such as TorGuard use this to allow BitTorrent in countries where it's forbidden; a SOCKS5 proxy can allow BitTorrent by being located in Canada while you're connected to no VPN server, or a VPN server located in the United States.

. Ability to port forward at least 5 ports while supporting IPv6; this gauges a VPN provider's attention to detail, even if you never need port forwarding.
** https://web.archive.org/web/20220731172057/https://teddit.net/r/VPNTorrents/comments/s9f36q/list_of_vpns_that_allow_portforwarding_2022/[List of VPNs that support Port Forwarding].

. If the OpenVPN protocol is supported, its tls-crypt must be supported and for the VPN provider to allow establishing connection to their servers via port 443.

** OpenVPN over SSL or SSH is mandatory for China, Iran, and Egypt.
. Full IPv4 and IPv6 support across all servers.
** On some telecoms, connecting to a VPN server through IPv6 is required.

. Reliable software across multiple operating systems.
** The most problematic: Android TV, iOS/iPadOS, and Linux (especially distros not based on Ubuntu or Fedora).
*** Linux support for most VPNs lack a graphical interface, and lack features included in their Windows and/or macOS VPN software.

TIP: https://web.archive.org/web/20220929090559/https://thatoneprivacysite.xyz/choosing-the-best-vpn-for-you/[An archive of "That One Privacy Site"], dated 19th December 2019. +
Use it as a second opinion on what justifies a good paid VPN provider.

___
====


.If the VPN can't connect.
[%collapsible]
====

. Check if IPv4 or IPv6 is being used to reach the VPN server.
** For T-Mobile, connecting through IPv6 may be required.
. If the VPN still can't connect, try each supported protocol in this order:
** WireGuard -> IKEv2/IPSec -> SoftEther -> OpenVPN (UDP, port 443) -> OpenVPN (TCP, port 443) -> OpenVPN over SSL (TCP, port 443)

[.lead]
Reasoning for each open-source VPN protocol choice:

* *WireGuard*: fastest on reliable internet; easily blockable by DPI firewalls.
* *IKEv2/IPSec*: sometimes faster than WireGuard on unreliable internet. Depending on the VPN provider, IKEv2 can either be resistant to DPI firewalls (hide.me's implementation), or not at all.
* *SoftEther*: bypasses most DPI firewalls with good speeds in general, but is more complicated to set up for non-Windows OSes.
* *OpenVPN3*: resistant to DPI firewalls if tls-crypt is used alongside port 443; China, Iran, and Egypt require OpenVPN over SSL which further reduce speeds. This protocol isn't efficient and has latency issues.

___
====


== Appendices

.Resources used
[%collapsible]
====

[.lead]
Learning

. https://archive.org/download/p173_20220313/p173.pdf
. https://archive.org/download/technology-showcase-policy-control-for-connected-and-tethered-devices/technology-showcase-policy-control-for-connected-and-tethered-devices.pdf
. https://archive.org/download/geneva_ccs19/geneva_ccs19.pdf
. Random XDA forums posts and threads to accumulate personal experiences with hotspot/tethering bypass attempts.

[.lead]
Third-party scripts

. `/jffs/scripts/wan-event` used for Asuswrt-Merlin is a refined version of https://www.snbforums.com/threads/wan-start-script-also-run-on-wan-stop.61295/#post-542636[this script].

___
====

*You've reached the end of this guide.* Star it if you liked it.