[asterisk-users] Newbie Dialplan: Best Practice in using Context - Do not use Default??

[C. Chad Wallace]

At 9:43 AM on 13 May 2008, Lee, John (Sydney) wrote:

> In "The future of Telephony", it says "... We should also note for
> security's sake you should always make sure that your [incoming]
> context never allows outbound dialing.  (If by chance it did, people
> could dial into your system and make outbound toll calls that would
> be charged to you!)
> 
> The book was demonstrating using a PSTN environment and the
> zapata.conf was something like:
> context=internal
> signaling=fxo_ks
> channel=>1
> 
> context=incoming
> signaling=fxs_ks
> channel=>2
> 
> In PRI environment, does it mean that we have to purposely separate
> the say ISDN 20 channels into [internal] and [incoming] as well?  
> This would not make sense to me as ISDN uses a one port card to
> contain multiple channels while the ports of a say TDM400P refer to
> each channel.
> 
> If I just define a [default] context for a PRI environment, is this
> insecure?
> 
> Can someone please enlighten me on this?

In the example you quoted, channel 1 is an FXS port, which would be an
internal extension--a phone--from which someone would be allowed to
make an outbound call.  Channel 2 is an FXO port, which is
connected to the PSTN, and would take incoming calls from "the
wild".  So in that example, you wouldn't want the "incoming" context to
be allowed to make outbound calls.

In your case, I'm guessing all your Zap channels come from the PRI,
which is connected to the PSTN.  If so, then you're right--you just
need one context for your zapata.conf which you would use on all your
ISDN channels.  Just don't let that context dial out.

I don't know if you'd want to call that context "default"... because
that one seems to be "special" in Asterisk.  But maybe I'm just being
superstitious. :-)


-- 

C. Chad Wallace, B.Sc.
The Lodging Company
http://www.skihills.com/
OpenPGP Public Key ID: 0x262208A0

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