This document provides instructions on how to build and configure Asterisk V1.6 with the OSP Toolkit to enable secure, multi-lateral peering. This document is also available in the Asterisk source package as doc/osp.txt. The OSP Toolkit is an open source implementation of the OSP peering protocol and is freely available from https://sourceforge.net/projects/osp-toolkit. The OSP standard defined by the European Telecommunications Standards Institute (ETSI TS 101 321) www.etsi.org. If you have questions or need help, building Asterisk with the OSP Toolkit, please post your question on the OSP mailing list at https://lists.sourceforge.net/lists/listinfo/osp-toolkit-client.
The software listed below is required to build and use the OSP Toolkit:
* OpenSSL (required for building) - Open Source SSL protocol and Cryptographic Algorithms (version 0.9.7g recommended) from www.openssl.org. Pre-compiled OpenSSL binary packages are not recommended because of the binary compatibility issue.
* Perl (required for building) - A programming language used by OpenSSL for compilation. Any version of Perl should work. One version of Perl is available from www.activestate.com/Products/ActivePer. If pre-compiled OpenSSL packages are used, Perl package is not required.
* C compiler (required for building) - Any C compiler should work. The GNU Compiler Collection from www.gnu.org is routinely used for building the OSP Toolkit for testing.
* OSP Server (required for testing) - Access to any OSP server should work. An open source reference OSP server developed by Cisco System is available at http://www.vovida.org/applications/downloads/openosp/. RAMS, a java based open source OSP server is available at https://sourceforge.net/projects/rams. A free version of the TransNexus commercial OSP server may be downloaded from http://www.transnexus.com/OSP%20Toolkit/Peering_Server/VoIP_Peering_Server.htm.
4) Compile OpenSSL according to the instructions provided with the OpenSSL distribution (You would need to do this only if you don<6F>t have openssl already).
5) Copy the OpenSSL header files (the *.h files) into the crypto/openssl directory within the osptoolkit directory. The OpenSSL header files are located under the openssl/include/openssl directory.
6) Copy the OpenSSL library files (libcrypto.a and libssl.a) into the lib directory within the osptoolkit directory. The OpenSSL library files are located under the openssl directory.
Note: Since the Asterisk requires the OpenSSL package. If the OpenSSL package has been installed, steps 4 through 6 are not necessary.
7) Optionally, change the install directory of the OSP Toolkit. Open the Makefile in the /usr/src/TK-3_3_6-20060303/src directory, look for the install path variable <20> INSTALL_PATH, and edit it to be anywhere you want (defaults /usr/local).
Note: Please change the install path variable only if you are familiar with both the OSP Toolkit and the Asterisk.
Note: Please make sure you have the rights to access the INSTALL_PATH directory. For example, in order to access /usr/local directory, root privileges are required.
Device enrollment is the process of establishing a trusted cryptographic relationship between the VoIP device and the OSP Server. The Enroll program is a utility application for establishing a trusted relationship between an OSP client and an OSP server. Please see the document "Device Enrollment" at http://www.transnexus.com/OSP%20Toolkit/OSP%20Toolkit%20Documents/Device_Enrollment.pdf for more information about the enroll application.
10) From within the OSP Toolkit directory (example: /usr/src/TK-3_3_6-20060303), execute the following commands at the command prompt:
cd enroll
make clean; make linux
Compilation is successful if there are no errors in the compiler output. The enroll program is now located in the OSP Toolkit/bin directory (example: /usr/src/ TK-3_3_6-20060303/bin).
The OSP module in Asterisk requires three crypto files containing a local certificate (localcert.pem), private key (pkey.pem), and CA certificate (cacert_0.pem). Asterisk will try to load the files from the Asterisk public/private key directory - /var/lib/asterisk/keys. If the files are not present, the OSP module will not start and the Asterisk will not support the OSP protocol. Use the enroll.sh script from the toolkit distribution to enroll Asterisk with an OSP server and obtain the crypto files. Documentation explaining how to use the enroll.sh script (Device Enrollment) to enroll with an OSP server is available at http://www.transnexus.com/OSP%20Toolkit/OSP%20Toolkit%20Documents/Device_Enrollment.pdf. Copy the files generated by the enrollment process to the Asterisk /var/lib/asterisk/keys directory.
Note: The osptestserver.transnexus.com is configured only for sending and receiving non-SSL messages, and issuing signed tokens. If you need help, post a message on the OSP mailing list at https://lists.sourceforge.net/lists/listinfo/osp-toolkit-client..
The enroll.sh script takes the domain name or IP addresses of the OSP servers that the OSP Toolkit needs to enroll with as arguments, and then generates pem files <20> cacert_#.pem, certreq.pem, localcert.pem, and pkey.pem. The <20>#<23> in the cacert file name is used to differentiate the ca certificate file names for the various SP<53>s (OSP servers). If only one address is provided at the command line, cacert_0.pem will be generated. If 2 addresses are provided at the command line, 2 files will be generated <20> cacert_0.pem and cacert_1.pem, one for each SP (OSP server). The example below shows the usage when the client is registering with osptestserver.transnexus.com.
./enroll.sh osptestserver.transnexus.com
Generating a 512 bit RSA private key
........................++++++++++++
.........++++++++++++
writing new private key to 'pkey.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [AU]: _______
State or Province Name (full name) [Some-State]: _______
Locality Name (eg, city) []:_______
Organization Name (eg, company) [Internet Widgits Pty Ltd]: _______
Organizational Unit Name (eg, section) []:_______
Common Name (eg, YOUR name) []:_______
Email Address []:_______
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:_______
An optional company name []:_______
Error Code returned from openssl command : 0
CA certificate received
[SP: osptestserver.transnexus.com]Error Code returned from getcacert command : 0
output buffer after operation: operation=request
output buffer after nonce: operation=request&nonce=1655976791184458
The files generated should be copied to the /var/lib/asterisk/keys directory.
Note: The script enroll.sh requires AT&T korn shell (ksh) or any of its compatible variants. The /usr/src/TK-3_3_6-20060303/bin directory should be in the PATH variable. Otherwise, enroll.sh cannot find the enroll file.
In Asterisk, all OSP support is implemented as dial plan functions. In Asterisk V1.6, all combinations of routing between OSP and non-OSP enabled networks using any combination of SIP, H.323 and IAX protocols are fully supported. Section
3.1 describes the three easy steps to add OSP support to Asterisk:
1. Build Asterisk with OSP Toolkit
2. Configure osp.conf file
3. Cut and paste to extensions.conf
Sections 3.2 and 3.3 provide a detailed explanation of OSP dial plan functions and configuration examples. The detailed information provided in Sections 3.2 and 3.3 is not required for operating Asterisk with OSP, but may be helpful to developers who want to customize their Asterisk OSP implementation.
The first step is to build Asterisk with the OSP Toolkit. If the OSP Toolkit is installed in the default install directory, /usr/local, no additional configuration is required. Compile Asterisk according to the instructions provided with the Asterisk distribution.
If the OSP Toolkit is installed in another directory, such as /myosp, Asterisk must be configured with the location of the OSP Toolkit. See the example below.
--with-osptk=/myosp
Note: Please change the install path only if you familiar with both the OSP Toolkit and the Asterisk. Otherwise, the change may result in Asterisk not supporting the OSP protocol.
The /etc/asterisk/osp.conf file, shown below, contains configuration parameters for using OSP. Two parameters, servicepoint and source must be configured. The default values for all other parameters will work well for standard OSP implementations.
;
; Open Settlement Protocol Sample Configuration File
;
; This file contains configuration of OSP server providers that
; are used by the Asterisk OSP module. The section "general" is
; reserved for global options. All other sections describe specific
; OSP Providers. The provider "default" is used when no provider is
; otherwise specified.
:
: The "servicepoint" and "source" parameters must be configured. For
; most implementations the other parameters in this file can be left
; unchanged.
;
[general]
;
; Enable cryptographic acceleration hardware.
;
accelerate=no
;
; Defines the status of tokens that Asterisk will validate.
; 0 - signed tokens only
; 1 - unsigned tokens only
; 2 - both signed and unsigned
; The default value is 0, i.e. the Asterisk will only validate signed
; tokens.
;
tokenformat=0
;
[default]
;
; List all service points (OSP servers) for this provider. Use
; either domain name or IP address. Most OSP servers use port 1080.
OSP functions are implemented as dial plan functions in the extensions.conf file. To add OSP support to your Asterisk server, simply copy and paste the text box below to your extensions.conf file. These functions will enable your Asterisk server to support all OSP call scenarios. Configuration of your Asterisk server for OSP is now complete.
The extensions.conf file example provided in Section 3.1 is designed to handle all OSP call scenarios when Asterisk is used as a source or destination gateway to the PSTN or as a proxy between VoIP networks. The extenstion.conf examples in this section are designed for specific use cases only.
The examples in this section apply when the Asterisk server is being used as a TDM to VoIP gateway. Calls originate on the TDM network and are converted to VoIP by Asterisk. In these cases, the Asterisk server queries an OSP server to find a route to a VoIP destination. When the call ends, Asterisk sends a CDR to the OSP server.
The examples in this section apply when Asterisk is being used as a VoIP to TDM gateway. VoIP calls are received by Asterisk which validates the OSP peering token and completes to the TDM network. After the call ends, Asterisk sends a CDR to the OSP server.