[asterisk-users] open up firewall ports for Asterisk - safe?

[Ryan Stille]

Right now I've been working on setting up an Trixbox server on our 
internal network.  Its behind the firewall, but I'd like to open up the 
firewall to it because we sometimes have developers working off site and 
I'd like them to be able to connect.

Is this safe to do?  I've got the "Allow Anonymous Inbound SIP Calls" 
box unchecked in freePBX.  Is there anything else I need to do?   Isn't 
there an issue with the extension/secret being passed in clear text?

It looks like I need to open port 5060, and whatever ports are inbetween 
the rtpstart/rtpend values in /etc/asterisk/rtp.conf.  Is that right?  
Right now thats 9999 ports, I've read that you can chop that down to 20 
ports for just a few calls.  We want to have 5-6 simultaneous calls, so 
if I set rtpstart to 10001 and rtpend to 10100, then open up those 
ports, is that adequate?

Thanks for any help.
-Ryan