Slightly less Random Ramblings

July 1, 2016

Installing OpenWRT on a Cheap Laptop

Filed under: computing, Firewall, linux, OpenWRT, security — Tags: , , , , , , — Robert Wicks @ 4:20 pm

I got a deal ($125) on an Acer ES1-111M laptop. This class of laptop is intended to be a Windows-running equivalent to Google’s Chromebook. It came with 8GB of RAM and an embedded 32GB eMMC drive. I gave it to my daughter, until the shoddy trackpad made it too frustrating for her and I got her a newer and better laptop. I upgraded the onboard RAM to 8GB. I’ve run Windows 10 and Ubuntu on it, but I don’t really need another personal laptop. Considering the RAM, the light weight, the low temperature and power usage, along with onboard Gigabit Ethernet and a USB 3.0 port, I figured it might make a decent VPN gateway.

I first set it up as a router, which led to the discovery that the existing router in my house, a Buffalo WZR-HP-G300NH, was holding me back. I had a USB 3.0 Gigabit Ethernet dongle as the second interface for the laptop, and when I set up simple IP Masquerading on Ubuntu and pointed a computer at it, I found that my download speeds jumped from ~70Mb/s to ~170Mbs. That led me to look for a wife-friendly (i.e., free) way to improve things. My first choice was my favorite firewall software, OpenWRT. There is an x86 version which is developed alongside the embedded device versions I am so accustomed to using. I grabbed the ISO, then discovered the issue I’ve seen with other Linux distributions, it would not see the storage. Eventually, I installed it to a USB key, which was fine. Along the way, I upgraded to the trunk build and discovered that the OpenWRT which was running could now see the (unused) MMC storage. Perhaps it would now work.

Initially, I wrote an image to the eMMC storage, and booted, but it froze during the boot process. After a bit of tinkering, I found out that if you edit the grub entry so that root=/dev/mmcblk0p2 rather than UUID=-2, it would boot correctly. After booting, just mount /dev/mmcblk0p1 to /mnt, then edit /mnt/boot/grub/grub.cfg to change the UUID entry to /dev/mmcblk0p2, and everything works correctly. You will need to install kmod-usb-net-asix-ax88179 to use the USB Ethernet adaptor. From there, it’s a very normal OpenVPN setup.

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