DIY: DVB-T Streaming server/Austria, Vienna

Despite the end of DVB-T is close, since DVB-T2 is already simulcasted in Austria, there may still be some use for this.

Germany is currently rolling out DVB-T2 HD and the availability of USB-Receivers has been announced. My hope is, that some of these devices will work in this setup as well. We’ll see.

What you need:

Continue reading DIY: DVB-T Streaming server/Austria, Vienna

OpenWRT and WLAN-USB-Sticks (Updated with an example)

USB-WiFi support in OpenWRT

Recently one of my blog’s visitors (Michael) asked me, if it was possible to extend his router with an additional USB-Wifi device. The short answer is: yes.
I’ll give you an example of a tested configuration below. If you are planning to use different parts, please check the  caveats here and be sure to get chipsets, that are known to work.

Continue reading OpenWRT and WLAN-USB-Sticks (Updated with an example)

Huawei E303 in fallback mode, OpenWRT: usb-mode.json explained

How I worked around usb-modeswitch issues with a Huawei E303s-2

If you need to use Huawei HiLink ™ devices on a router running OpenWRT, you most probably will want to use them as a dumb serial modem.

Continue reading Huawei E303 in fallback mode, OpenWRT: usb-mode.json explained

Do you know socat – Multipurpose relay?

Socat, evaluating possibilities

is another swiss army knife of networking. It incorporates an amazingly big set of use cases. There are yet some to be invented.

Socat’s README explains it function as follows:

socat is a relay for bidirectional data transfer between two independent data
channels. Each of these data channels may be a file, pipe, device (serial line
etc. or a pseudo terminal), a socket (UNIX, IP4, IP6 - raw, UDP, TCP), an
SSL socket, proxy CONNECT connection, a file descriptor (stdin etc.), the GNU
line editor (readline), a program, or a combination of two of these. 
These modes include generation of "listening" sockets, named pipes, and pseudo

So what do with socat?

Continue reading Do you know socat – Multipurpose relay?

ZTE MF831 for use with OpenWRT: serial modem instead of cdc_ether

How to turn a ZTE MF831 into a dumb serial modem

Update and warning:

This article was written for the austrian version of the ZTE MF 831 back in October 2015. It is probably outdated by now. Most of the information contained herein and in the comments stems from my own and other user’s findings,,, archlinux and various other sources. I still own two ZTE MF831, which I regularly use. I used to have them in modem mode and are now using both in CDC mode. I can affirm, that switching modes -back and forth- works for these two models (Sw. WEB_HOFAUTMF831V1.0.0B02, Fw. BD_HOFATMF831V1.0.0B02, Hw. MF831-1.0.0).

Nevertheless, if you are not experienced in Android ADB, Linux, networking principles, terminal commands (AT/Hayes), you better restrain from reading on. You should really should be an expert in all that, if you decide to continue at your own risk.

Why that warning?

In the recent years I received some comments from people, some posts contained constructive feedback and experiences for which I am grateful. Comments of all that kind correspond to the way, a community works and are highly appreciated in order to improve a ‘howto’ like this.

Today (June, 9th 2019) I received quite the opposite: A posting, that contained mere hate speech, and menace against my family and me, blaming me for advising to send back a device, that up to my experience, was a defective in the first place.

I’d therefore like to repeat, that the mode switching commands are implemented by the manufacturer, ZTE himself. (The device’s OS is Android; mode switching by sending a HTTP request, simply invokes an AT command server and disables networking capabilities on USB; likewise, corresponding AT commands revert that). These command lists can be found at several places on the net, and they even work on various other ZTE models, but with variations, that you need to do research on. The commands used here partially even had been previously published by ZTE Australia and were republished in 2012 and relinked e.g. at, but after several website redesigns at ZTE, the manual is no longer available at the referenced link. Check they wayback archive at your convenience: At no point in the main article did I describe any alteration of the firmware, unless for naming the possibility of firmware recovery, which relies on firmware, that the manufacturer published  officially through it’s distributor back in the year 2014.

Until today, I received one report of one completely unresponsive MF831, which is most probably caused by a defective flash chip – and another similar experience, where a modeswitch never even has been tried:

A brand new MF831 my employer had used at home, got defective after two weeks in service in combination with an original TP-Link MR3240. The replacement LTE stick -also a MF831- is in service until today.

I also had two other defective MF831, but the problem I encountered with both, was a mere mechanical defect: A ‘triple sim card’ (nano, micro, mini) got loose somehow and it’s adapting frame and got entangled with pin 5 when I tried to exchange the sim card. That resulted -and that’s at no surprise either- in an ‘unavailabe network’ message.

What I have published then, back in 2014, was to the best of my  knowledge and belief and represents the steps I did, that worked for me  repeatedly.

I, personally, think the modeswitch, that is undocumented in the users manual, but well known among router programmers, is safe to use on the devices I’ve tested. A risk still remains – you have been warned.

Your alternatives are:

a. OpenWRT nowadays works like a charm with USB cdc devices. So, if you don’t have a contract with a public IP and you don’t need port forwarding – simply use the stick in it’s  default mode and stop reading.

b. Get a professional LTE routing equipment, that costs far more than the MF831’s lousy 25 Euros , if it’s still in stock. It’s successor, the MF833V will be sold for as low as 29,99 Euros starting next week…

c. Get another device, that is configured/flashed to use serial mode by default.

So, dear readers – you, once more, have been warned not to read on.

If you decided otherwise, here is the original article:

Background story:
Recently the austrian discounter Hofer started to sell equipment capable of LTE and bundled it with SIM cards of it’s MNVO HoT (Hofer Telekom).

Among those items is a relatively cheap LTE class 4 modem – the ZTE MF831.
Optically it is unbranded, but it seems to contain a firmware optimized for HoT.

Continue reading ZTE MF831 for use with OpenWRT: serial modem instead of cdc_ether

IEEE 802.11ac – first devices

According to an article on, dated 4th June 2012, Asus demonstrated their first router which complies to IEEE 802.11ac – also referred to as ‘gigabit wlan’ [- edit: which may be a misleading term in some cases]: the ‘RT-AC660U‘.

The same magazine performed tests on a set of Buffalo devices: Router WZR-D1800HClient WLI-H4-D1300. These are interesting aspects, despite the standard 802.11ac has not yet been released. So consider, that these devices can only be compliant to the actual draft version. Unfortunately no information about support of OpenWRT is known at this time.

Edit: June 8, 2012:
Even more devices have been announced today, so this post will be edited continuously to reflect new development:


WZR-D1800H (Router)
WLI-H4-D1300 (Client)

BR-6673AC (Router)
BR-6476AC (Router)

TEW-812DR (Router)
TEW-800MB (Bridge)

Remarks and caveats: Some of the announced devices seem to be hybrid developments. E.g.: There are 802.11ac devices, that only use 2 MIMO streams. As a result only around 800Mbit can be achieved. Other devices, especially some usb sticks don´t use their full potential, if they do not support USB 3.0, but rather USB 2.0.
The effective data rate will never exceed the nominal 480Mbit in that case.

I will try to make a list containing Manufacturer, Chipset, interfaces and, where applicable, ram, cpu and flash size. Unfortunately most manufacturers still don’t print that necessary information on their boxes or ever data sheets.

Disclaimer: Any of the trademarks, service marks, collective marks, design rights or similar rights that are mentioned, used or cited within this post are the property of their respective owners.

Entry point

Welcome to ‘technical experiments’!

End of may, 2012 I discovered a need to publically document some of my it project’s I did in my spare time. Some of those projects had to do with things I could not go into more deeply during work.
The reason for me to start a blog was, to have place, a dump, where I could post snippets of code and other things, that would otherwise be stored to a word document on my hard disk oder even on google drive, where it could collect dust and rust and be of limited use only.
The motivation to do so are many helpful articles out there on the net, that I appreciate. I am trying to contribute to that community by blogging here, too.
Some things are common problems, some are very special. In case a problem comes up again, I may not be able to retrieve the same search result again some years later. So I am going to preserve that junk of information here.
My interests are especially 
  • Linux
    • and especially debian, ubuntu,
    • OpenWRT, DD-WRT, Gargolye et cetera
  • Networking in general
    • with the cheapest tunable components available, if possible (cheap SoC-Routers, VLAN, …)
    • WiFi for Home and SoHo use
    • WiFi in directional applications (Wireless mesh network principles)
    • (Mesh) Routing protocols
    • stable use of 2G/3G/4G for connected home (in a ‘home improvement’ way, …;-)
  • Hosting
    • all kinds of network services.
  • some more
It’s likely that I am going to post some of my leisure works’ outcome here.
Hopefully someone in the  community out there can make use of it.

So here we go… welcome to my way of wasting time…