June 2005
Intermediate to advanced
502 pages
21h 48m
English
Content preview from Switching to VoIP
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
This is the Title of the Book, eMatter Edition
Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.
Intrusion Prevention and Monitoring
|
237
• In order for an RTP call path to exist between the PSTN gateway and the IP
phone, no rules need to be set up on the firewall, since both are on the same seg-
ment.
• As a matter of course, all hosts accessing services on the DMZ should have the
ability to resolve DNS hostnames, and so TCP and UDP port 53, for DNS, should
be permitted from 10.1.1.10 and 10.1.1.103 to the DNS server, 28.26.11.5.
At this point, assuming the VoIP network itself is configured to handle the calls via
dial-plans and channels, and so on, PSTN subscribers can call the IP phone, and the
IP phone can call the PSTN, even though the SIP proxy is on the DMZ. But what was
really accomplished through all this was security. Use a similar exercise to identify
the additional TCP/IP traffic flows required to support an Internet-based SIP calling
application through firewall A:
• In order to communicate with Internet-based SIP hosts, the SIP proxy at 28.26.11.4
must be able to send and receive SIP traffic (UDP ports 5060 and 5061).
• In order to provide DNS name resolution for SIP services, the DNS server at
28.26.11.5 must be able to send and receive DNS traffic (TCP and UDP port
53) to and from the Internet.
• The SIP proxy can already communicate with the IP phone and the PSTN
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.