Installing and Configuring an Asterisk Conference Bridge for the NCS Club

Konrad Armitage & Matthew LapinskiNCS 416

Prof. Ronny BullNovember 21st, 2013

Project Scope

Installation of an Asterisk server on a physical device to be used by the NCS club

Installation & configuration of a conference bridge to allow multiple users from inside and outside the network to hold group meetings.

Equipment

Dell PowerEdge 860 serverDevices for testing

Computers, cellphones etc.Hardphones and SoftphonesHeadsetsPacket analyzer (Wireshark & TCPdump)

Planning Stages

Setup Asterisk on physical serverDeveloped layout for network configurationsWork with Sys Admins to implement

networkingDiscuss choice between MeetMe() and

ConfBridge()Setup SIP trunkTest abilities of the serverTroubleshoot problems.

Networking and Installation

Installation of CentOS and AsteriskDevicesConfiguration filesModules

NetworkingArrangements with CS Sys AdminPort configurationsSetup of SIP trunk

Asterisk Installation

CentOS 6.4 x86_64 minimal installAsterisk 2.6.32 from source

* Initially created on NCS Club network and migrated to the 10.107.0.0 /16

Solving NAT Issues on a Campus Network

1) Publicly routable address2) DNAT on external interface

DNATDestination Network Address Translation

Pre-processing alteration (doesn’t change source address)Changes the destination address to specified address

Example:

Asterisk server at 10.107.1.98

Packet destined for 150.156.201.22-> Destination address changed to 10.107.1.98

Solving NAT Issues on a Campus Network

Firewall Rules

UDP 5060 (SIP)TCP 5061 (SIP/TLS)UDP 10000-10200 (RTP)TCP 22 (SSH)UDP 123 (NTP)

Initial Testing

Internal connections successful

Could register externally but: Inbound connections without audio Could not initiate calls

Problem Solving?

CS system administrator dropped inbound firewall rules

Inbound connections began to work

SIP Trunk

With inbound connections working successfully, an outbound SIP trunk from SIP.us was created.

Free trial with 60 minutes

Outbound call successfully tested to cellular network

TroubleshootingAsterisk

Problems with MeetMe() and ConfBridge()Incorrect port usage/assignmentErrors in configuration filesErrors between connections of outside users to

internal users

Concluding Thoughts What went right?

Setup Troubleshooting Testing

What could we have done? MeetMe() IAX2 Reduce modules loaded for efficiency

How can we build on this? Paid SIP trunk Publically available number Admin settings for conference Video conferencing OpenSSL Improved hardware