"Unable to open master device" error

Comment on Asterisk Fedora Core 3

Compilation caveat

Posted:Mon 31 of Jan, 2005 (20:59 UTC)
A really brief note on the (great) installation instructions that I'm embarassed to say tied me up.

I installed OS, downloaded zaptel and asterisk as directed. I had a minor problem with one of the X100Ps (IRQ conflict, I think) and so restarted without completing the zaptel compilation / 'make install' in order. Installed and config'd asterisk with internal SIP phones to test installation and went back and fixed the zaptel installation second.

Everything seemed to be fine: zttool & /proc/zaptel reported devices were OK, configs were stock (as per examples), asterisk was working fine, but I couldn't get either dial-tone on the FXS channel phones or get a response from asterisk on dial-in on the FXO channel.

I figured out finally that the chan_zap.so hadn't been compiled during the asterisk install (due to the unsatisfied dependency on the initial zaptel compile). This is easily verified in asterisk itself using the zap * commands (ie 'zap show channels') - if they're not there / not available, it's not installed.

A simple re-compile/install (in order!) of zaptel and asterisk patched everything up nicely and didn't even disrupt the config files. Sorry about doubting you, asterisk.


Re: Re: "Unable to open master device" error

Posted:Tue 07 of Dec, 2004 (06:16 UTC)
Recommend you always use the service command — if you install FC3 with SELinux strict policy (as opposed to targeted policy) then you will more-than-likely be running something from rc*.d/init.d with the wrong context (your current one as shown with the "id" command) where as if you use the "service" command as a front-end to rc*.d/init.d then they will start with the proper context. Again, this depends on the SELinux policy in effect (for now we have strict & targeted but users can certainly roll their own too which is why it's important to get right now :-). Thanks!
Joined: Mon 31 of May, 2004

Re: "Unable to open master device" error

Posted:Tue 07 of Dec, 2004 (05:43 UTC)
nope, i had the same problem, and jean's solution had the same effect. I found that doing modprobe wcfxo after starting the zaptel service made my x100 work... added the init.d fix to the page.

"Unable to open master device" error

Posted:Mon 22 of Nov, 2004 (03:22 UTC)
Thank you for posting this - it was a great help. I am a complete newbie to both Linux and Asterisk. I followed your instructions and was able to get a working configuration using a single X101P card (for my PSTN interface) and a few softphones.
However, my excitement at my apparent success diminished rapidly after I restarted the system and got the following error.
Notice: Configuration file is /etc/zaptel.conf
line 143: Unable to open master device '/dev/zap/ctl'

So I poked around and came up with the following fix on the "Asterisk Linux Fedora" page of this WIKI.

edit the Zaptel Make file and comment out the following lines

ifeq ($(DYNFS),)
@echo "**** Dynamic filesystem detected — not creating device nodes"
@echo "**** If you are running udev, read README.udev"

Applying this fix got it working again - but only for the current login session. The same error occured after the next restart.

I then applied steps 9 & 10 from the "installing on Fedora 2" section of the same page (Edit the file /etc/init.d/zaptel) and this helped - somewhat. Now I can restart and if I perform a ztcfg -vvv command (manually) after logging in but before starting Asterisk I can then start and run Asterisk properly.
Have I done something wrong or is there a fundamental problem here (since I apparently am not the only one to run into this problem)?

chris vince