Presentation from AsteriskWorld 2017 at ITEXPO. Discussion of how I started with Asterisk and Kamailio as well as how to build Reliability, Scalability, and Security into your telephony platform.

1. Using Asterisk and Kamailio for Reliable,
Scalable and Secure Communication Solutions

2. Using Asterisk and WHAT?????
Kah-mah-illie-oh
● Kamailio
● Hawaiian word
– to communicate
– to coverse

3. Who am I?
● Fred Posner
● @fredposner
● https://qxork.com

7. Better Together

8. Let’s start at the beginning...

9. Why Did I Switch to Asterisk?
“...many needs are actually wants. And
there’s a good chance you can save more
money simply redesigning a business
process than it would cost to support those
customization wants.”
—Experts at Mitel

11. Needless to say...
● Features
● Ability to customize
● Stability
● Scalability (growth)
● Licensing/Long Term Cost

12. Registrations
Carrier Routing
Security
Call Handling
Media
Queues

13. Features You Need
● Transcoding
● B2BUA
● AGI (Gateway Interface)
● ARI (Rest Interface)
● Database Integration
● ISDN/PRI/Analog
● SIP
● WEBRTC
● Custom CDRS
● Full PBX features
● IVR
● Call Center
● Conferences
● Too Much to List

14. ● 5k — 20,000 users in 3
months
● 6 Asterisk Servers
● 2 AcmePacket (HA)
● > 1 million min/month
We Experienced Rapid Growth

15. Fiber Cut… x2
● Thundering Herd
● Replaced AcmePacket with
Kamailio (OpenSER)

16. Enter Kamailio (OpenSER)
● SIP Proxy Server
● SIP Registrar Server
● SIP Location Server
● SIP Application Server
● SIP Dispatcher Server
● SIP Websocket Server

17. Kamailio Provides
● Modular Design
● Modular SIP Proxy, Registrar and
Redirect server
● IPv4, IPv6, UDP, TCP, TLS, SCTP,
WebSocket
● NAT Traversal, internal and external
caching engines
● JSON, XMLRPC, HTTP APIs
● IMS Extensions, SIP-I/SIP-T, IM &
Presence
● SQL and NoSQL backends
● Asynchronous processing
(TCP/TLS, SIP routing),
external event API
● Embedded interpreters (Lua,
Perl, Python, .Net, Java)
● Load balancing, LCR, DID
routing, Number portability

18. Kamailio is not...
SIP Phone
Media Server
B2BUA
Asterisk Does what Kamailio
Does Not

19. Can I SBC?
● No
– Not a B2BUA
– No Transcoding
– Etc.
● Well…
– Inconceivable
– Do you want a “true” SBC?
Please read Alex Balashov’s great article:
➔ http://osolo.co/sbc (redirects to https://likewise.am)
➔ “Kamailio as an SBC (Session Border Controller)”

20. Tell me more!
● 150+ Modules
● Many Modules for Security
● Dedicated Resources
● Protects Multiple Servers
Where does he get those toys?

21. Security
● SQL Injection?
● Friendly Scanner?
● Script Kiddies?
A SIP Server needs not these
things.

22. SQL Injection & UA Filtering
if ($ua =~ "(friendly-scanner|sipvicious|sipcli)") {
sl_send_reply("200","OK");
exit;
}
if($au =~ "(=)|(--)|(')|(#)|(%27)|(%24)" and $au != $null) {
sl_send_reply("200","Drop Table LOLz");
exit;
}

23. Improved Security
● SIP Brute Force Attacks
– Registrations, calls, etc.
● User-Agent Filtering
– Sipvicious, Scanners, etc.
● IP Authentication
● SQL Injection
● LOG Injection
● Spoofing
● Centralized Security

24. Deploying Kamailio & Asterisk
Internet
ASA
pfsense
etc.
Kamailio Asterisk
Asterisk Asterisk
Asterisk
SIP/RTP

25. Scalability — LCR
Asterisk
NAT
Kamailio
Public IP
Asterisk
NAT
Asterisk
NAT
Carrier 1
Carrier 2
Carrier 3
Internet
PSTN

26. Scalability — Load Balancing
Asterisk
NAT
Kamailio
Public IP
Asterisk
NAT
Asterisk
NAT
Internet
PSTN

27. Scalability — Load Balancing HA
Asterisk
Inbound
Kamailio
Public IP
Asterisk
Recorded
Asterisk
Inbound
Internet
PSTN Asterisk
Queue
Asterisk
Voicemail
Asterisk
Queue

28. Scalability — Scaling
Asterisk
Inbound
Kamailio
Public IP
Asterisk
Recorded
Asterisk
Inbound
Internet
PSTN Asterisk
Queue
Asterisk
Voicemail
Asterisk
Queue
Kamailio
Public IP
Asterisk
Queue
Asterisk
Inbound
Asterisk
Inbound
Carrier Carrier Carrier
Carrier Carrier Carrier

29. Choosing Hardware
● Too many considerations
– SQL on same box?
– RTP Proxying on same box?
– Dialog sessions?
● Calls per second?
● Simultaneous calls?
● Kamailio is very fast
● Can store much in RAM
● As with everything context is
king

30. 500cps Example

31. With great power
comes great
responsibility.

32. 500cps Example
● 4 core (ARM)
● 1GB RAM
● 1GB NIC
● Dispatcher
● RTPENGINE
● Raspberry Pi 3

33. What about Virtualization?
● Simple answer, yes.
● Large amount of
deployments
● Not a simple question
● Pros/Cons approach works
best

34. In Summary...
Asterisk
Inbound
Kamailio
Public IP
Asterisk
Recorded
Asterisk
Inbound
Internet
PSTN Asterisk
Queue
Asterisk
Voicemail
Asterisk
Queue
Kamailio
Public IP
Asterisk
Queue
Asterisk
Inbound
Asterisk
Inbound
Carrier Carrier Carrier
Carrier Carrier Carrier

35. Questions? Cookies?
Fred Posner
@fredposner
https://qxork.com
● Kamailio
– kamailio.org
● Asterisk
– asterisk.org
– Digium.com