DUNDi configuration

In order to keep our config files clean, we created 2 seperate files for resp. the extensions and the iax-config. These files are:

extensions_gijs_ruben.conf
iax_gijs_ruben.conf

These are included in the following files: extensions.conf:

#include extensions_gijs_ruben.conf

iax.conf:

#include iax_gijs_ruben.conf

Configuring DUNDi

(Source)

Warm up your favorite text editor, because we're going to edit three Asterisk configuration files. The three files are dundi.conf, iax.conf, and extensions.conf. These are in /etc/asterisk/ on Asterisk@Home. dundi.conf controls peer authentication, iax.conf is our transport protocol, and extensions.conf contains your dialplans.

This example connects two peers, MyHost and OtherHost.

First edit iax.conf. Add the following lines, except for any that are duplicated in the [general] section:

[dundi]
   type=user
   dbsecret=dundi/secret
   context=dundi-local
   disallow=all
   allow=ulaw
   allow=alaw
   allow=g726

Now edit dundi.conf. The default file is well commented and has lots of examples--you'll find definitions of all the directives in there. This is where your mapping contexts are defined, which follow this format:

dundi_context => local_context,weight,technology,destination,[options]

The following configuration creates two DUNDi mapping contexts:

[general]
;put your own information here
department=Boss's office
organization=Alrac, Inc.
locality=Portland
stateprov=OR
country=US
email=hrh@alrac.com
phone=15035551212
;
bindaddr=0.0.0.0
port=4520
;
;use the server's MAC address for the entityid
entityid=11.22.33.44.55.66
cachetime=3600
ttl=32
autokill=yes
secretpath=dundi
;
[mappings]
;copy this as shown, substituting your own server and hostname
;this should be one long unbroken line
dundi-peer1 => dundi-priv-local,0,IAX2,dundi:${SECRET}@myhost.mynet.com ${NUMBER},nounsolicited,nocomunsolicit,nopartial
;our OtherHost peer is configured here
;and is allowed access only to dundi-peer1
[aa:bb:cc:dd:ee:ff] ;MAC address of otherhost.elsewhere.com
 model = symmetric
 host = otherhost.elsewhere.com
 inkey = otherhost.elsewhere.com
 outkey = myhost.mynet.com
 include = dundi-peer1
 permit = dundi-peer1
 qualify = yes
 dynamic=yes

You need to create RSA authentication keys for your server. You may name them anything you want; a good naming convention is to use your server's fully-qualified domain name. Create keys with these commands:

# cd /var/lib/asterisk/keys
# /usr/sbin/astgenkey -n myhost.mynet.com

This creates two keys: myhost.mynet.com.pub and myhost.mynet.com.key. The public key, myhost.mynet.com.pub, must be distributed to all servers you are peering with. Post it on your Web site if you like. The private key is unencrypted, and like all private encryption keys must be guarded carefully. Then the res_crypto.so line interface:

# asterisk -r
asterisk1*CLI># reload res_crypto.so
asterisk1*CLI># reload pbx_dundi.so

From here you can also run the command show keys to see all of your RSA keys. Now go back to iax.conf and add the dundi user.

Here is a quick Linux tip: you don't have to exit the Asterisk CLI to return to the Linux command line. If you're logging in remotely, just open a second SSH session. If you're on the Asterisk server, switch to a second console with Alt+F2.

This allows remote access to your server:

[dundi]
 type=user
 dbsecret=dundi/secret
 context=dundi-priv-local
 disallow=all
 allow=ulaw
 allow=g726

dundi/secret is an encryption key automatically generated by Asterisk. You may view this key by running the database show command from the Asterisk CLI.

Finally, edit extensions.conf; this is where you define what numbers to share and what to do with them. Telephone numbers must follow this format:

country_code area_code prefix number

This is a simple example that answers incoming calls, directs them via the SIP protocol to extension 200, which is the digital assistant, sends the caller to voicemail if there is no answer, then hangs up.

[dundi-priv-local]
 exten => 15035551212,1,Answer( )
 exten => 15035551212,n(call),Dial(SIP/200)
 exten => 15035551212,n,Voicemail(u200)
 exten => 15035551212,n,Hangup( )

SIP registration

Add the following to sip.conf:

regcontext=sipregistration

Once the phones, in this example 201 and 202 register with the PBX, a context of [sipregistration] appears and can be shown in the Asterisk CLI:

asterisk1*CLI> show dialplan sipregistration
[ Context 'sipregistration' created by 'SIP' ]
  '201' =>          1. Noop(201)                                  [SIP]
  '202' =>          1. Noop(202)                                  [SIP]
-= 2 extensions (2 priorities) in 1 context. =-

DUNDi CLI-checks

• dundi lookup:

asterisk1*CLI> dundi lookup 301@priv bypass
  1.     0 IAX2/priv:ByWFbOGKgGmZbM43BJHSZw@2.4tw.nl/301 (EXISTS)
     from 00:0c:29:d2:d8:ec, expires in 3600 s
DUNDi lookup completed in 113 ms

asterisk1*CLI> dundi lookup 202@priv
  1.     0 IAX2/priv:+DmRAz4RjwF6GQMC3zopfQ@1.4tw.nl/202 (EXISTS)
     from 00:0c:29:e4:14:80, expires in 3570 s
DUNDi lookup completed in 13 ms

• Asterisk DUNDi debug - Analysis of DUNDi traffic with Asterisk's debug.
• List of Asterisk1.4 dundi-CLI-commands

Alternatives to DUNDi

You can also try the TDMoE zaptel driver. This is similar to the ztdummy driver in some ways but it will link 2 or more PBX's on the same physical network with zap channels. So on a 100Mb ethernet interface you could potentially get the equivalent of about 50 PRI lines. Overkill maybe, but you can set the number of channels you want. This should be good for interconnecting a voicemail only Trixbox with another tribox handling the calls. In larger installs this would be useful as it offloads the voicemail agi scripts and transcoding to another box. TDMoE is also much simpler to configure in comparison to DUNDI.

you get many of the same features as you do with normal zap channels. It is also very efficient on bandwidth and cpu.

DUNDI is a good solution for remote PBX's. (Source)