Posts with the category Networks

Huawei E5332 – Portable UMTS WiFi Router with Battery

I paid £30.00 for the Huawei E5332 Unlocked Mobile Wi-Fi Modem on Amazon UK.

It has a TS9 antenna connector (source).

There's an Android app to control/monitor it: HUAWEI Mobile WiFi 3

Default Settings


The website of the router makes extensive use of...

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Netgear AirCard 762S (NETGEAR AirCard 4G LTE Mobile Hotspot)

Login / Web Interface

  • Web UI Address: http://aircard.hotspot/
  • Web UI IP Address:
  • Default Admin Password: webadmin
  • Web address for shared microSD card: http://aircard.hotspot/dav//

Short Specs

  • Supports up to 100 Mbps download, up to 50 Mbps upload (LTE Category 3)
  • LTE 800/1800/2100/2600
  • HSPA+/HSPA 900/2100 MHz
  • Dual band 2G
  • WiFi 802.11 b/g/n
  • Dimensions: 97.5 mm x 57 mm x 15.7...

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Enabling Regdomains on OpenWrt Routers

By default, the OpenWrt images ship with only US regdomains for WiFi. This is annoying if you live anywhere outside the United States. Here are two different ways to fix this:

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Connecting to Samba shares on Linux / One-way Sync

Using Samba (or SMB) shares on Linux is not difficult but you should know some tricks. First of all, you can use smbclient to probe your Samba-Server and try to connect to it. You can then mount an SMB-share locally.
In addition, I wrote a tool to synchronize a local directory with...

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Intel Gigabit ET Dual Port Server Adapter

Details about how a recent Linux sees the card: Intel Gigabit ET Dual Port Server Adapter on Arch Linux (Kernel v3.16)

NIC Bonding on Arch Linux

Simple bonding setup as described in the Arch Wiki:

sudo pacman -Sy ifenslave
cp /etc/netctl/examples/bonding /etc/netctl/bonding
vim /etc/netctl/bonding
# -------- content: ----------

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Deploy Your Own Bind9 based DDNS Server

This post is based on my previous blog post, Updating DNS Entries (with nsupdate or alternative implementations) – Run Your Own DDNS, and on Cédric Félizard's post "Your Own Dynamic DNS".

Running your own DynDNS (DDNS) server is easy when you have your own domain registered and an own...

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AVM FRITZ!Box 7490

Hardware Components

  • SoC: Lantiq GRX388 - Feature-rich SoC for 2x2/3x3 WLAN, 3xGE Gateway
  • Modem: Lantiq VRX318 - ADSL2/2+/VDSL Transceiver and Line Drive
  • WiFi: Qualcomm Atheros QCA9880 - 3-stream 802.11ac radio solution

Network Call Monitor

Activate the feature by calling:

#96*5*    activate call monitor support
#96*4*  deactivate call monitor support

Then you...

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Using the ipaddress module that comes with Python3.3+

from ipaddress import IPv4Network, IPv6Network

a = IPv4Network('')
b = IPv4Network('')
c = IPv4Network('')

x = IPv6Network('2000::/64')
y = IPv6Network<span...

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Deciding between a RPi colocation and hosting it yourself at home

The Raspberry Pi colocation costs 36 EUR incl. VAT per year, see here. If you spend this amount of money for energy only, it's:

Yearly Energy = 36 EUR/year / 0.27 kWh/EUR * 1000 Wh/kWh = 133 333 Wh / year
# to enter it more quickly in your calculator:

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Enabling Wake on Lan on an Arch Linux Computer

ip addr
ethtool enp1s0f0
ethtool enp1s0f1
ethtool -s enp1s0f0 wol g
ethtool enp1s0f0

What the g or the other options mean is stated here (source):

p Wake on phy activity
u Wake on unicast messages
m Wake on multicast messages
b Wake on broadcast messages
a Wake on ARP
g Wake...

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Solving NAK DHCP Problems with the Fritz!BOX 7490 router

If you encounter problems like these:

dhcpcd[13577]: eth0: broadcasting for a lease
dhcpcd[13577]: eth0: offered from
dhcpcd[13577]: eth0: reject NAK via

Online you will find a lot of old threads suggesting things like commenting out the line require dhcp_server_identifier in the file dhcpcd.conf. Didn't help in my case.

This happened...

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Intel PRO/1000 PT Dual-Port-Server-Adapter (PCIe x4) | vendor product site chipset: Intel 82571GB (supported by e1000e driver)

Instead of this one I would buy an Intel ET Server, 2x 1000Base-T, PCIe x4 for ~130 EUR including SR-IOV support. I have another blog post for that card: Intel Gigabit ET Dual Port Server...

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Software I Install Right After Flashing A Bleading Edge OpenWrt trunk Version

Here are a couple of packages I install whenever I upgrade to a new trunk version of OpenWrt. I do this because the ability to install all those packages will only last for a couple of days until there will be a new trunk version with a different kernel. So...

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OpenWrt on a TP-Link TL-WDR4900 Router

The TL-WDR4900 is a Gigabit router made by the Chinese network equipment producer TP-Link.

Hardware Information

CPU Flash RAM Network WAN USB Serial
P1014 16MB 128MB 4x1 GigE 1x1 GigE x2 v2.0 Yes

The most important chips:

  • CPU: Freescale Semiconductor P1014
  • Switch: Atheros AR8327N
  • WiFi:
    • 2.4 GHz: Atheros AR9381
    • 5 GHz: Atheros AR9580

The power supply of this device has...

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Start AutoSSH on System Startup Using Systemd on Arch Linux

OK, here is how to start ssh on system startup (this is the content of the systemd .service configuration file /etc/systemd/system/autossh.service):

Description=AutoSSH service for a reverse tunnel from to localhost

ExecStart=/usr/bin/autossh -M 0 -q -N -o "ServerAliveInterval 60"...

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Public NTP Servers

PTB Servers



Find more NTP servers on:


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Dynamic Routing with BIRD Running the IPv6 based OSPFv3 Protocol on OpenWrt

This is somehow a follow up of the older post IPv6: Dynamic Routing with Quagga and ospf6d (OSPFv3).

I'm switching from Quagga to BIRD to manage dynamic routing using the OSPFv3 protocol on my networks. BIRD is a slim routing daemon in use by quite some internet exchange points...

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A Collection Of Reliable Public DNS Servers

TODO: Write a script to ping all the IPs and find the best (fastest). Put it online as a gist on GitHub.




  • 2001:4860:4860::8888
  • 2001:4860:4860::8844

Level3 / AT&T



  • - Orange DNS (ISP)
  • - DNS Advantage




  • 2620:0:ccc::2
  • 2620:0:ccd::2



  • 2001:5c0:1000:11::2
  • 2001:5c0:1001::194

How To Find Out Who's Operating a DNS Server

Run whois on the IP:

philipp@lion:~$ whois

Google Incorporated LVLT-GOOGL-1-8-8-8...

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OpenWrt on a TP-Link TL-MR3020 Router

This is a really compact and cheap router to take with you to hotels etc. to secure your internet access via VPN or redistribute a network.

The Hardware

You can get some information on the used hardware from my /proc/cpuinfo, /proc/meminfo and dmesg.

I put some photos I made of...

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Generate Bind Reverse Zone File Using A Simple Python Script

When I had to create a reverse DNS zone file for my Bind name server I wanted it to be as flexible as possible and thus created a Python script that generates the Bind zone file. This makes renumbering the network really easy.

The script is available as a gist...

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Make RS232 Serial Devices Accessible via Ethernet


The RFC 2217 standardizes the transmission of serial connection data via Ethernet, allowing to change remote serial port parameters (such as speed, parity, stop bits) over TCP using NVT (Network Virtual Terminal).


Connection between your serial device and the Ethernet

  • YPort - a hardware and software solution (microcontroller AVR ATmega based...

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Query DNS on MS Windows

To query a DNS entry for a domain name, here run this command on the Windows PowerShell:


And the opposite, get a hostname from an IP address:




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IPv6 Adresses

Defined in RFC 5156

  • ::1/128 is the loopback address
  • ::/128 is the unspecified address
  • ::FFFF:0:0/96 are the IPv4-mapped addresses (indicating devices that are not IPv6-capable)
  • ::<ipv4-address>/96 are the IPv4-compatible addresses, deprecated!
  • fe80::/10 are the link-local unicast addresses
  • fc00::/7 are the unique-local addresses
  • 2001:db8::/32 are the documentation addresses. They are used for documentation purposes such as user manuals,...

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Get your own DNS server up and running with Bind9 on Ubuntu or Debian

The goal of this article is to describe how to setup your own DNS server to serve the domain name service entries for a TLD ( In the last part of the article I describe how to increase the speed of the system and the security in...

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Private Subnet with Ubuntu as Router

Suppose we have the following setup:

  • A Computer with Ubuntu installed and two physical network interfaces (might also be virtual, but that's advanced)
  • We have an internet connection on this computer set up and working. Internet traffic goes out (and in) on the network interface eth2
  • We want to create a private subnet
  • The...

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Watch the network for an IP conflict - ipwatchd

Installation on Ubuntu:

sudo aptitude install ipwatchd-gnotify

if configured correctly (true by default) it will show you graphical warnings for IP conflicts as well as create log entries in /var/log/syslog (check for log messages containing ipwatchd).

Advanced configuration options are described and have to be set in the file/etc/ipwatchd.conf. This could...

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How to use tcpdump

You can use tcpdump to debug TCP/IP connections.

How it works

1st console run tcpdump:

philipp@lion:~$ sudo tcpdump -i lo
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on lo, link-type EN10MB (Ethernet), capture size 96 bytes
09:55:05.968006 IP lion > lion: ICMP echo request, id 5745, seq 1,...

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