OpenWrt installation instructions for Arris TR4400 v2 / RAC2V1A

Requirements

• A linux box (Windows and macOS should also work but have not been tested).
• Serial port access to the router (more info here).
• Ethernet connection to the router (Wi-Fi connection should also work but has not been tested).
• Serial port terminal software (eg: gtkterm).
• SSH and SCP client software with configued keys.

Note: While issuing the SCP commands detailed bellow, you might encounter errors related to option -O not being recongnized. In such a case, simply leave out the -O option from all SCP commnands. This happens if you are using an SCP version older than 8.7 (use ssh -V to check your version). The option is required on recent SCP versions due to deprecation of the old SCP/RCP protocol. More details here.

Preparation

1. Clone this repository.
2. Download OpenWrt initramfs (kernel) and squashfs (sysupgrade) images for this router to the checkout directory.
3. Edit enable-ssh-template.txt and paste your public RSA SSH key where indicated in the file.
4. Connect the serial cable, open the terminal, and boot up the router.
5. When booting is finished, press ENTER to access a root console.
6. Paste the contents of enable-ssh-template.txt into the console to enable SSH access.
7. Connect to the router via Ethernet or Wi-Fi using manual IP 192.168.1.2 or DHCP.
8. Pop up a terminal in the checkout directory and verify SSH access by typing:

ssh root@192.168.1.1 "cat /proc/version"

• Output should be similar to:

Linux version 3.14.43 (mark@sercomm-QCA-Server) (gcc version 4.8.3 (OpenWrt/Linaro GCC 4.8-2014.01 r1121) ) #1 SMP PREEMPT Thu Mar 1 14:52:59 CST 2018

9. Run a check of the state of your router:

ssh root@192.168.1.1 sh <check-svn1418.sh

• Output should be similar to:

This script checks the current state of your router in depth.
If all checks pass, you are good to go on installing OpenWrt.
The router USB port should be empty when running this script.

checking /proc/cmdline
checking /etc/svn.info
checking /etc/openwrt_release
checking /proc/version
checking /proc/mtd
checking /proc/mounts
checking /proc/bus/pci/devices
checking fw_printenv
checking dmesg-ubi-attached
checking dmesg-ubifs-mounted
checking ubi0_0-kernel
checking ubi0_1-ubi_rootfs
checking ubi0_2-rootfs_data

WARNING: Do not proceed installing OpenWrt if any errors were output!
Save the output and seek help in the forums instead.

• Do not proceed if errors are shown in the ouput!

Backup the stock firmware

1. Create and transfer backups of all MTD partitions:

ssh root@192.168.1.1 sh <mtd-backup.sh
scp -O root@192.168.1.1:/tmp/lanchon/mtd-backup.tar .
ssh root@192.168.1.1 "rm /tmp/lanchon/mtd-backup.tar"

2. Create and transfer backups of all UBI volumes:

ssh root@192.168.1.1 sh <ubi-backup.sh
scp -O root@192.168.1.1:/tmp/lanchon/ubi-backup.tar .
ssh root@192.168.1.1 "rm /tmp/lanchon/ubi-backup.tar"

• You might need these backups down the road, so store them.

Install OpenWrt

Make sure you have backups of the stock firmware (see previous section); each device is different.

1. Install the initramfs recovery image:

scp -O openwrt-[...]-arris_tr4400-v2-initramfs-uImage root@192.168.1.1:/tmp/recovery.bin
ssh root@192.168.1.1 sh <install-recovery.sh

2. Sysupgrade to the squashfs image:

• Reboot router and connect to http://192.168.1.1/cgi-bin/luci/admin/system/flash.
• Click on Flash image... and choose the squashfs image.

3. Reconnect to http://192.168.1.1/ and profit!

Update the recovery image

There is usually no reason to upgrade the recovery image. This is provided for completeness.

1. Download the OpenWrt initramfs (kernel) image for this router.
2. Pop up a terminal and write the recovery image (replace 192.168.1.1 with the address of your router):

scp -O openwrt-[...]-arris_tr4400-v2-initramfs-uImage root@192.168.1.1:/tmp/recovery.bin
ssh root@192.168.1.1 'ubiupdatevol /dev/ubi0_9 /tmp/recovery.bin && rm /tmp/recovery.bin'