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Post-Root Procedures

Stop!

Do not follow any post-root procedure unless explicitly told to in a previous step of this guide.

Bank Planning

We are now going to prepare an optimal bank plan for the same firmware version you have now booted.

Run the following command to look at your Gateway's bank state:

find /proc/banktable -type f -print -exec cat {} ';'

You should see something like this being printed:

xxxxx
/proc/banktable/booted
<take note of this>
/proc/banktable/active
<take note of this>
xxxxx

If the above command failed, your board is not dual bank and no bank planning is possible. Otherwise, take note of the current active and booted banks.
This guide will let you setup your Gateway to boot the same firmware you are now running as per optimal bank plan. An optimal bank plan looks like this:

/proc/banktable/active
bank_1
/proc/banktable/booted
bank_2

We will now do what your current state requires to match the above one, such that the device will boot from the recommended bank on every reboot.

Which bank should I use to stay safe?

It's strongly recommended to stick to the above mentioned optimal bank plan before applying any further mod to your device. The bigger picture description is available here. The short thing is that you should really mod your preferred firmware version (not necessarily of Type 2) only while it's being booted from bank_2 and keep bank_1 as the active one.
Key Point: it's unsafe to deeply mod any firmware which is being booted from bank_1.

Notable exception: Missing RBI

In the unfortunate case that there are no RBI firmware files available for your board, you are not in a safe position because you can't rely on BOOTP firmware recovery. The optimal bank plan relies on BOOTP to flash and clean-boot a firmware from bank_1. Your best option is to ensure you keep a copy of a rootable Type 2 firmware on both banks and to avoid modding one of them. Please, check the firmware repository page for any available RBI and stop following this bank planning guide if there are none.
In case some RBI firmwares are available but none of them is of Type 2, the hereby described optimal bank plan is still fine, despite some limitations.

Run the following commands:

# Ensure two banks match in sizes
[ $(grep -c bank_ /proc/mtd) = 2 ] && \
[ "$(grep bank_1 /proc/mtd | cut -d' ' -f2)" = \
"$(grep bank_2 /proc/mtd | cut -d' ' -f2)" ] && {
# Clone and verify firmware into bank_2 if applicable
[ "$(cat /proc/banktable/booted)" = "bank_1" ] && \
mtd -e bank_2 write /dev/$(grep bank_1 /proc/mtd | cut -d: -f1) bank_2 && \
mtd verify /dev/$(grep bank_1 /proc/mtd | cut -d: -f1) bank_2 || \
{ echo Clone verification failed, retry; exit; }
# Make a temp copy of overlay for booted firmware
cp -rf /overlay/$(cat /proc/banktable/booted) /tmp/bank_overlay_backup
# Clean up jffs2 space by removing existing old overlays
rm -rf /overlay/*
# Use the previously made temp copy as overlay for bank_2
cp -rf /tmp/bank_overlay_backup /overlay/bank_2
# Activate bank_1
echo bank_1 > /proc/banktable/active
# Make sure above changes get written to flash
sync
# Erase firmware in bank_1
mtd erase bank_1;
# Emulate system crash to hard reboot
echo c > /proc/sysrq-trigger }
# end

If everything went good, the Gateway will intentionally crash. Wait for it to reboot completely.
You should now be in the previously mentioned optimal bank plan. On each reboot, your device will try booting active bank first. Since we set bank_1 as active and we also erased bank_1 firmware, it will boot from bank_2.

Upgrade now!

Would you like to upgrade to a newer firmware? This is the perfect moment for doing it. It is now safe to also install non-Type 2 firmwares. Just follow the Safe Firmware Upgrade guide for this. You could also upgrade later in future and continue tweaking the current firmware. Once you did install the updated firmware, come back here and continue reading.

At this point, you now need to check if your SSH server setup is permanent.

Setting up Permanent SSH Server

Are you connected to SSH on port 6666? In most cases, the answer is "No, I didn't need to specify port 6666, I've got connected on default port 22". You don't need to run the below commands if you can already connect on default port 22, your SSH setup is permanent already.

If the answer is "Yes", run these commands to setup a permanent SSH access on port 22 by defining a new dropbear instance:

uci -q delete dropbear.afg
uci add dropbear dropbear
uci rename dropbear.@dropbear[-1]=afg
uci set dropbear.afg.enable='1'
uci set dropbear.afg.Interface='lan'
uci set dropbear.afg.Port='22'
uci set dropbear.afg.IdleTimeout='600'
uci set dropbear.afg.PasswordAuth='on'
uci set dropbear.afg.RootPasswordAuth='on'
uci set dropbear.afg.RootLogin='1'
uci commit dropbear
/etc/init.d/dropbear enable
/etc/init.d/dropbear restart

Now proceed to changing your root password, this is mandatory.

Change the Root Password

Serious hint!

Do not ignore this step! Your firmware was probably designed to work only on certain specific ISP network. Some kind of remote SSH access could be left open by design in such a way only that same ISP could access. Connecting to some different ISP network could lead to this open access to be exposed on the internet.

Run:

passwd

Now you must harden your access, to prevent it from being lost because of limited RBI availability or automatic firmware upgrades in future. See Hardening Root Access page.