Just another hacking blog
Back in the day I created a set of scripts for 3G and LTE modems to use under Debian: they used PPP chat scripts and custom udev rules for convenience. That’s all obsolete now. NetworkManager and Modemmanager hide all the modem communication under the hood, and you only need to initialize them properly. The following […]
As PCengines announced the end of sales of their famous APU platform, it’s time to look for alternative devices that can be utilized as firewalls or network probes or VPN appliances. I bought recently a Qotom Q20321G9 mini-PC from AliExpress. The model is similar to their Q20331G9 model described on Qotom website. The difference is […]
Digital Ocean is offering a private LAN for internal communication between the VMs, and they claim it’s isolated from other customers. You get some random addresses within 10.133.0.0/16 (or maybe some other range), and they can talk to each other on dedicated virtual NICs. But that’s it. You cannot run OSPF because multicast packets are […]
A Linux device, such as PC Engines APU, can be equipped with an LTE modem, but sometimes it’s desirable to use the mobile connection only if the wired connection is unavailable. The following scenario is for Debian 9 on an APU box, but it’s also applicable to any other Linux device. The DHCP client is […]
Ubiquiti EdgeRouter X is a tiny and cheap (around $50) router with a decent amount of memory: 256MB RAM and 256MB flash. The router offers 5 GigE copper ports, and there’s also a model with an additional SFP port. The device is produced since 2014, and it’s still up to date and a good value […]
Here’s a new repository for OpenVPN deployment scenarios and example configurations: https://github.com/txlab/ovpn-scripts At the moment it lists two scenarios with configuration generation scripts: routed VPN for remote management bridged VPN for anti-censorship isolation of a home LAN
SIMCom SIM7100E is a recent LTE modem released by Simcom. It’s approximately $20 cheaper than Huawei LTE modem, and also it provides USB voice function, so it could be integrated with FreeSWITCH mod_gsmopen module (this needs development). My set of udev rules and chat scripts is updated with SIM7100E information, and here’s a copy: cat […]
NanoPi NEO Plus2 is a brand new board released by FriendlyELEC. It’s slightly bigger than the NEO2 board, and packed with much more cool stuff: 1GB RAM, Wifi+Bluetooth module, and 8GB eMMC chip. It has also two USB2.0 port connected to independent USB controllers. The NanoPi NEO Plus2 Basic Kit accompanies the board with an […]
tested with VCSA 6.1 and vSphere replication 6.1.1. OVF Tool 4.2.0 is installed on a Debian Jessy machine. ovftool --acceptAllEulas -ds=datastore1 \ -n=<VMname> --ipAllocationPolicy=fixedPolicy \ --prop:password='*******' \ --prop:ntpserver=******* \ --vService:installation=com.vmware.vim.vsm:extension_vservice \ vSphere_Replication_OVF10.ovf vi://vcenter01.domain.com/DC1/host/Cluster1/
The NanoPi NEO2 board by FriendlyElec has several options for an enclosure in their webshop. The 3D-printed plastic enclosure is of too poor quality, and it doesn’t fixate the heatsink properly on the CPU. The acrylic case does not include washers, which makes the whole construct too fragile, as the screws can easily damage the […]
PC Engines GmbH has recently released a new board, APU3. The difference from APU2 is that two mPCIe slots are suitable for 3G or LTE modems, whereas APU2 had only one such slot. This article explains how to utilize two HUAWEI ME909 LTE modems, and it’s applicable to other modems too. One of the LTE […]
My physical machine runs Debian Jessie, and it has several LXC containers (mostly Debian and Ubuntu). Now I needed to test some software under CentOS, and I bumped into the following error when installing Apache HTTP server: Downloading packages: httpd-2.4.6-45.el7.centos.4.x86_64.rpm | 2.7 MB 00:00:00 Running transaction check Running transaction test Transaction test succeeded Running […]
NanoPi NEO2 by FriendlyElec is a new sub-$20 Linux microcomputer, built on Allwinner H5 SoC, providing a Gigabit Ethernet and USB 2.0 interface. Also additional interfaces are possible via expansion headers (needs some soldering work). The board is equipped with 512MB DDR3 RAM. It is highly recommended to buy the heatsink alongside with the board. […]
Orange Pi Zero with 512MB RAM, expansion board and black case is sold for sub-$20, including postal costs, and it is so far the cheapest Linux device you can buy. Armbian project provides a dedicated image for this board. The nightly build is quite stable, and there’s also legacy kernel which works well. The computer […]
A customer has its own PI range of public IP addresses, and they way to use part of this range in a remote office and place some servers there. The remote office is connected via some third-party ISP. So, the VPN tunnel should route the customer’s addresses and provide full Internet access to the remote […]
Chuwi Hi10 Pro (CW1529) tablet is sold for about $200 with an attachable keyboard, which makes it a potential candidate to replace my old Acer Aspire One and run Linux on it. It’s also equipped with a high-quality 10″, 1920×1200 IPS screen. The tablet is based on Intel Atom x5-Z8350 Cherry Trail CPU, which requires […]
Here’s a sequence of commands in an ssh session to an ESXi host that creates a VM backup without interrupting its work. Of course it’s only a snapshot of the disk, so there may be corrupted files as a result. vmkfstools command requires full file path for the source and destination VMDK files. # This […]
In this github repo, I put together my knowledge about WWAN cards setup, alongside with all initialization scripts.
Huawei ME909s-120 is the newest modem of Huawei LTE/UMTS family, and it is sold for around $70 at TechShip.se and at Aliexpress. The modem is immediately recognized as CDC Ethernet device in Debian 8 kernel, and is visible as usb0 interface. In the scripts below, the ttyUSBx serial ports are aliased to ttyWWANxx, and usb0 […]
Sometimes there’s a need to reset a GSM module on a Yeastar GSM gateway. For example, SIM cards of one of our providers get into faulty state every few weeks, and only a reset helps. The GSM module can either be rebooted via Web GUI, or from the Asterisk console. But the Asterisk console can […]
Our good old Samsung Galaxy Tab 3 7.0 Kids Tablet has finally died after over 3 years of everyday heavy use, so I needed a new solution. So far, here is the best combination that I could find: This silicon case for Samsung Galaxy TAB A 7″ SM-T280 is a solid and protective piece, and it […]
In my particular case, there are two physical USB devices that are represented as TTY devices in the kernel: a Gobi2000 3G modem, and a 4-port USB-to-serial adapter. The modem is presented by two ttyUSB devices, and the USB-to-serial adapter adds four more. At the machine boot, these devices get assigned random numbers ttyUSB0 to […]
If you install FreeSWITCH 1.6 on Debian 8 from official .deb packages, and then add FusionPBX on top, the server boot sequence needs a modification: now FreeSWITCH configuration depends on the presence of Postgresql server, and it would load an empty configuration if the database service is not available at the moment of start. This […]
tcpkali is a lightweight and easy-to-use tool that allows you to generate a traffic load with multiple TCP sessions. You push the load in one or both directions at the same time. Also the tool works easily over a NAT’ed connection. This tool is great if you need to test QoS for VoIP applications. Here’s […]
Novatel E371 (also known as Dell DW5804) is sold for less than $30 at Aliexpress, and it’s so far the cheapest 4G/LTE WWAN card suitable for PC-Engines APU. The initialization is fairly simple, although it was tricky to find the right command (AT$NWQMICONNECT=,,). cat >/etc/chatscripts/lte_on.E371 <<'EOT' ABORT BUSY ABORT 'NO CARRIER' ABORT ERROR TIMEOUT 10 […]
Qualcomm Gobi 2000 is quite old (released 2009), but decent 3G modem, able to deliver up to 7Mbps in downstream in PPP mode. These modems in mini-pcie packaging are available at Aliexpress for less than $10, and make up a great option for 3G connectivity for PC Engines APU boards. The modem needs a binary […]
The scripts for integrating FreeSWITCH with Sevana AQuA software are now available at github: https://github.com/voxserv/fsqa More details on what they are doing are available in this older post: https://txlab.wordpress.com/2015/06/02/quality-assurance-for-voip-calls-2/
It’s a quite common task that you need to translate an IP address into a prefix — for example, when creating an IP prefix list from a set of addresses. Here’s a simple Perl script that helps it: sudo apt-get install libnetaddr-ip-perl cat >getprefix.pl <<'EOT' use strict; use warnings; use NetAddr::IP; if( scalar(@ARGV) == 0 […]
UPD: the FreeSWITCH integration scripts are available at https://github.com/voxserv/fsqa A customer has requested to set up a QA service that would continuously monitor the voice quality in their telephony infrastructure. They use a number of telephony carriers, and a set of applications on top of Plivo and FreeSWITCH. Also the conference module in FreeSWITCH is […]
I needed to test some master-slave software in a situation that the master communicated to the slave over NAT (master’s IP address was replaced with the firewall’s external address), and then NAT would be removed, keeping master and slave addresses the same, but the slave would see the master directly. This is the test scenario […]