Inside ZTE MF286 router

ZTE MF286 4G router is built around Qualcomm QCA9563 soc with 802.11bgn, QCA9882 802.11ac wlan, QCA8337 gigabit switch and MDM9230 LTE chip. There's also tempting serial port knowing all components used are already supported by LEDE (that has replaced OpenWrt).

Photos here.

Linux SNAT with per-connection source address from IP pool

When doing NAT with pool of addresses to choose from (instead of masquerading) Linux insists on always using same IP from pool for particular source IP. Often this is preferred, but not always. To workaround we need to patch kernel a bit.

Controlling Anel Elektronik NET-PowerControl HOME from command line

There's probably proper api to do this, but everything is in German and all I wanted to do is toggle status of single power outlet from script.

curl --data "F0=S" http://admin:admin@192.168.1.3/ctrl.htm -o /dev/null

Remapping bad sectors with Linux and dd

I have one faulty non-RAID disk on server which I can't replace right now so I wanted to see if I could mask problems by manually triggering bad sector reallocation.

Adding aufs support to Ubuntu LTS 14.04 with 3.16-rc5 kernel

Adding aufs support to 3.16-rc5 is little different than what is was for older kernels. Below works for Ubuntu LTS 14.04.

Flashing BeagleBone Black (rev B, 2GB eMMC) with Ubuntu 14.04

You're supposed to be able to use "BBB-eMMC-flasher" images to flash new OS directly from SD card. For whatever reason this sometimes fails to work. People blame power supplies which probably is one reason but not this time. In my case when trying to use BBB-eMMC-flasher image BBB started flashing all four user leds in sync without ever even attempting to flash image to eMMC.

Ubuntu 13.10 with TCP-IR (TCP Instant Recovery / FEC) enabled kernel v3.4.83

How would FEC (Forward Error Correction) enabled TCP/IP stack for Linux sound like? Yep, I know you're interested and want it. Start by checking these two links.
http://www.ietf.org/proceedings/87/slides/slides-87-tcpm-8.pdf
http://tools.ietf.org/html/draft-flach-tcpm-fec-00

Remote conversion of 32-bit CentOS 6.3 to 64-bit Ubuntu 13.10

Pretty much any Linux should be fine as long as you have suitable scratch partition for temp Ubuntu install, in this example we're re-using 6GB swap partition. Process is two step, first we do minimal 32-bit Ubuntu install over swap partition, boot system, hack it to 64-bit and finally do final 64-bit Ubuntu install over old CentOS rootfs.

Updating Seagate ST3000DM001-9YN166 to CC4H firmware while in external USB 3.0 enclosure

Some time ago I purchased external 3TB USB 3.0 hard disks, TrekStor DataStation maxi light 3TB to be exact. It seem disk models and manufactures used by TrekStor vary, which is no surprise. Therefore I have externally identical disk enclosures with three different models of disks due making three separate purchases over few months.

Enable TRIM for SSD with ext4, dmcrypt and md

Depending on why you're encrypting your SSDs it might be acceptable to enable TRIM (aka discard). With this configuration observing raw content on SSDs will reveal which blocks are used and which aren't. Doesn't matter for me, but might not be same for you.

Gaining root shell on Huawei B593 4G LTE router

Huawei B593 has "few" security issues. If you want to play around here's some tips.

NTFS undelete on Linux

To avoid damaging filesystem with files to be undeleted I created image of entire hard disk by booting live linux on source PC from USB and then making 1:1 copy of HDD with dd.

Fixing non-bootable CentOS 5 after VMware converter P2V

Did P2V for old CentOS 5.5 i686 install and it failed to boot. Recreating initrd helped. Also see thread on VMware support forums.

Smartmontools 6.1 on Ubuntu 12.04

Please see updated version: http://blog.asiantuntijakaveri.fi/2015/07/smartmontools-v64-and-ubuntu-1204.html

Linux and unwanted disk spinups

Some process was spinning my suspended USB disks back up every few minutes which is bad, mmkay. To monitor processes accessing disks I used following commands

ZFS using USB3 disks

Intel Core i5-2400, 4GB RAM, 11 x Seagate 3TB USB hard disks connected via 4 x D-Link USB3 hubs to StarTech PEXUSB3S400 PCIe card. Ubuntu 12.04 with ZFS 0.6.1. Disks were configured as RAID-Z3 (triple parity).

write: 137438953472 bytes (137 GB) copied, 250.822 s, 548 MB/s
read:  137438953472 bytes (137 GB) copied, 197.451 s, 696 MB/s