Category Archives: linux

linux kernel related stuff

Sending UDP packets from the command line

Although is pretty easy to write a perl/python script to send UDP data, I wanted to be able to send a UDP message from the command line to test some code quickly. After 15 seconds of googling I found the … Continue reading

Posted in linux | 19 Comments

Busy November 2011

I attended 3 Linux/Telephony events in this past November 2011. All of them are focused on the Latino American community. Find the presentations below: – Elastix World 2011, Mexico D.F. Nov 3-4 – “Negociación de codecs en Asterisk” – FSL, Vallarta, … Continue reading

Posted in asterisk, freeswitch, linux, voip | Leave a comment

Linux Core Dumps

Note that most of the theory (particularly the low level segmentation fault details) are also valid for Windows platforms and other operating systems. The commands to configure core dumps and retrieve them are Linux specific though. I also assume that … Continue reading

Posted in asterisk, freeswitch, linux | 3 Comments

Wanpipemon cookies: ISDN pcap traces

PRI and BRI telephony links use the Q.931 and Q.921 protocols in its respective D-channel for call control and link reliability respectively. It is sometimes required to analyze protocol messages in a given link in order to troubleshoot call problems. Wanpipemon makes possible … Continue reading

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GIT hooks

I started using git hooks to update a clone repository with git pull just after every push to the repository. It was a bit of a pain to get it to work. The hook kept complaining about “fatal: Not a … Continue reading

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I hate SELinux

I am not a security-savvy person, even though I know pretty well how to code defensively to avoid security issues in my C code, my security knowledge in a Linux system is pretty average (use firewall, do not run services … Continue reading

Posted in C/C++, GNU/Linux General, linux | 2 Comments

Quick tip for debugging deadlocks

If you ever find yourself with a deadlock in your application, you can use gdb to attach to the application, then sometimes you find one of the threads that is stuck trying to lock mutex x. Then you need to … Continue reading

Posted in C/C++, linux | 1 Comment

New Project – Sangoma Bridge

A couple of months ago I wrote a little application for Regulus Labs. The application is a simple daemon bridge between Sangoma E1 devices receving ISDN PRI calls and a TCP IP server. Everything received on the telephony side was … Continue reading

Posted in C/C++, linux | 2 Comments

Debugging information in separate files

Debugging information in Linux ELF binaries is usually stored in the binary itself. This had been really convenient to me, for example, I always compile my openr2 library with -ggdb3 -O0. I don’t care about optimizations nor the increase in … Continue reading

Posted in C/C++, linux | 1 Comment

GNU autotools tip

When you create a program or library for Linux you may need GNU auto tools (automake, libtool, configure etc) to detect environment settings. These tools may become a pain in the ass when you start with them (and probably later … Continue reading

Posted in linux | 1 Comment