[kwlug-disc] AsteriskNow?

Lori Paniak ldpaniak at fourpisolutions.com
Sat Jul 31 18:00:29 EDT 2010


On Sat, 2010-07-31 at 15:15 -0400, unsolicited wrote:
> John Van Ostrand wrote, On 07/31/2010 8:59 AM:
> > ----- Original Message -----
> > 
> >> All the Asterisk-based distros I've seen suffer from this
> >> near-fatal flaw. It is astounding how poor their commitment to
> >> system security is.
> >> 
> >> While starting with a bare Debian install and building your own
> >> VoIP box would solve the security problem(s), I think you would
> >> be better off using a porous distro and adding firewall software.
> >> Then you can restrict access until you are satisfied. I use
> >> Shorewall to give a (more) user-friendly interface to iptables.
> >> Shorewall has great documentation - especially for typical cases.
> >> Just open up UDP ports 5060-5080 for SIP and 10000-30000 for RTP
> >> and you should have a functional, secure VoIP system.
> > 
> > I agree with Lori. Starting with the distro and turning off or
> > securing the things you want is a fast way to success. A firewall
> > alone won't work for you if you want one or more of the web-based
> > applications.
> > 
> > Run netstat -a to see which ports are listening and go from there.
> > Then inspect your apache config and see what you have to secure or
> > turn off.
> > 
> > I find turning things off, checking configs and changing passwords
> > is far easier than integrating all that software.
> 
> How un/reasonable is it to consider oneself 'sufficiently' 'safe' in 
> this (distro) situation? (Behind a firewall, and only the mentioned 
> ports opened and directed to the box.)
> 

If you only open the UDP ports I specified, your system will not appear
on TCP port scans.  The only outstanding security issue that I know of
is that of VoIP phreaks who try to gain access to insecure extensions on
your Asterisk system.  This can be cured by (1) setting ACLs and (2)
strong SIP registration passwords.  If all your extensions are on the
LAN side of your system and you take these precautions, I don't see how
it can be compromised from the outside.

> Assuming no internal hardware such as line cards, in the home (with 2 
> or 3 ATA devices, 1 POTS, perhaps 2 'extensions' which might be 
> multi-handset cordless phones), how un/reasonable is it to expect 
> 'sufficiently' acceptable performance when running such distros within 
> a vm? I guess I'm assuming the hardware is dual-core, and 2 - 4 GB 
> memory. I'm not assuming it is the only vm, but I guess I'm assuming 
> sufficient resources exist to run each vm in a 'reasonable' manner.
> 

Historically, running VoIP in a VM has been problematic due to timing
issues.  This may be a thing of the past, but I suspect you will want to
run your VoIP system on bare metal and put everything else in VMs.  So
long as you have no more than a concurrent call or two and not much disk
thrashing, you will probably get acceptable performance from the setup
you describe.

If you've got this server hardware currently running, the barrier to
starting up a trixbox VM is pretty low. You could test internal
performance like echo test, voice prompts and voicemail to see how it
works.  If you find that acceptable, you can add in a DID from Unlimitel
for $3.50/month and evaluate external call performance.

> Perhaps I'm asking the impossible here, given everyone will have their 
> own definitions for 'sufficiently', 'safe', and 'reasonable'. Perhaps 
> 'reasonable' is not ecstatic, but also not particularly unhappy. (JJ 
> said to me a long, long, time ago "You pick it up, you get dial tone." 
> - you're happy, or, at least, satisfied, and not unhappy.)
> 

That's the beauty of open source:  You can pull the security blanket up
as high as it takes to feel comfortable.  You do not have to settle for
someone else's definition of secure.  Reasonable performance is more
difficult.

> I have a suspicion that I could run a mythbuntu (with kde), plus 2 or 
> 3 vms (one of these distros, and egroupware, and courier e-mail either 
> with egroupware or in its own vm) and be 'sufficiently' satisfied. 
> When performance is insufficient, perhaps I'm streaming HD in and out 
> simultaneously, move egroupware/courier to a vm on another machine, 
> and keep going. Is this a fantasy world?

Is mythbuntu driving a display?  Then you're probably asking too much.
If it is just a backend server and not transcoding, then you might be
able to get away with it.  With lots of disk and network I/O from HD
streams, it gets even more dicey. Typically, you'll want dedicated
hardware for these situations.

Of course, that's my take on your questions.  I have never run mythbuntu
with KDE on my Asterisk system.

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