Browsed by
Tag: GSM

Static binaries (for Go with Docker)

Static binaries (for Go with Docker)

These days Go is quite popular for server based systems (read “cloud”) and one of the nice attributes is that compiling an application results in a single binary with no external dependencies (there is no “runtime” it has to link to). This makes deploying (read “copy to machine”) super easy and is a big contrast to something like Ruby on Rails and its thousands of dependencies. IIRC this feature was attractive to the developers of Qt’s coin (continuous integration agent)…

Read More Read More

Funding the Osmocom Cellular project

Funding the Osmocom Cellular project

My friend and business partner has recently blogged about funding of the Osmocom Cellular Infrastructure Projects and while I want to write about the history of sysmocom s.f.m.c. GmbH I will focus on getting contributions (or as a replacement monetary support) for the project. First of all I think the existence of Osmocom and Osmocom Cellular made a significant difference. It is used to provide connectivity to those previously ignored (Thank you everyone involved with Rhizomatica!) and we enabled mobile communication security research. This…

Read More Read More

CAMEL and protocol design

CAMEL and protocol design

Today I want to share the pain of running a production 3GPP TCAP/MAP/CAP system and network protocol design in general. The excellent Free Software ASN1/TCAP/MAP/CAP stack (which is made possible by the Pharo live programming environment) I helped creating is in heavy production usage (powering standard off-the-shelf components like a SGSN, an AuC or non-standard components to enable new business cases) and sees roaming traffic from a lot of networks. From time to time something odd comes up. In TCAP/MAP/CAP messages but also…

Read More Read More

MariaDB Galera and custom health probe for Azure LoadBalancer

MariaDB Galera and custom health probe for Azure LoadBalancer

My Galera set-up on Kubernetes and the Azure LoadBalancer in front of it seem to work nicely but one big TODO is to implement proper health checks. If a node is down, in maintenance or split from the network it should not be part of the LoadBalancer. The Azure LoadBalancer has support for custom HTTP probes and I wanted to write something very simple that handles the HTTP GET, opens a MySQL connection to the destination, check if it is connected to…

Read More Read More

Starting with a Diameter stack

Starting with a Diameter stack

Going from 2G/3G requires to learn a new set of abbreviations. The network is referred to as IP Multimedia Subsystem (IMS) and the HLR becomes Home subscriber server (HSS). ITU ASN1 to define the RPCs (request, response, potential errors), message structure and encoding in 2G/3G is replaced with a set of IETF RFCs. From my point of view names of messages, names of attributes change but the basic broken trust model remains. Having worked on probably the best ASN1/TCAP/MAP stack…

Read More Read More

Analyze cellular problems using Quectel modules

Analyze cellular problems using Quectel modules

Introduction Previously I have written about connectivity options for IoT devices and today I assume that a cellular technology (e.g. names like GSM, 3G, UMTS, LTE, 4G) has been chosen. Unless you are a big vendor you will end up using a module (instead of a chipset) and either you are curious what the module is doing behind its AT command interface or you are trying to understand a real problem. The following is going to help you or at least…

Read More Read More

C++, Qt and Treefrog to build user facing web applications

C++, Qt and Treefrog to build user facing web applications

In the past I have written about my usage of Tufao and Qt to build REST services. This time I am writing about my experience of using the TreeFrog framework to build a full web application. You might wonder why one would want to build such a thing in a statically and compiled language instead of something more dynamic. There are a few reasons for it: Performance: The application is intended to run on our sysmoBTS GSM Basestation (TI Davinci DM644x). By modern…

Read More Read More

osmo-pcap capture on the edge and store in the center

osmo-pcap capture on the edge and store in the center

Imagine you run a GSM network and you have multiple systems at the edge of your network that communicate with other systems. For debugging reasons you might want to collect traffic and then look at it to explore an issue or look at it systematically to improve your network, your roaming traffic, etc. The first approach might be to run tcpdump on each of these systems, run it in a round-robin manner, compress the old traffic and then have a…

Read More Read More

Build or buy a GSM HLR? Is there an alternative?

Build or buy a GSM HLR? Is there an alternative?

The classic question in IT is to buy something existing or to build it from scratch. When wanting to buy an off the shelves HLR (that actually works) in most cases the customer will end up in a vendor lock-in: The vendor might enforce to run on a hardware sold by your vendor. This might just be a dell box with a custom front, or really custom hardware in a custom chasis or even requiring you to put an entire…

Read More Read More

osmo-pcu and a case for Free Software

osmo-pcu and a case for Free Software

Last year Jacob and me worked on the osmo-sgsn of OpenBSC. We have improved the stability and reliability of the system and moved it to the next level. By adding the GSUP interface we are able to connect it to our commercial grade Smalltalk MAP stack and use it in the real world production GSM network. While working and manually testing this stack we have not used our osmo-pcu software but another proprietary IP based BTS, after all we didn’t…

Read More Read More