Asterisk OSP Module User Guide

June 16, 2006

Table of Contents
1        Introduction
2        OSP Toolkit
2.1      Build OSP Toolkit
2.1.1    Unpacking the Toolkit
2.1.2    Preparing to build the OSP Toolkit
2.1.3    Building the OSP Toolkit
2.1.4    Installing the OSP Toolkit
2.1.5    Building the Enrollment Utility
2.2      Obtain Crypto Files
3        Asterisk
3.1      OSP Support Implementation
3.1.1    OSPAuth
3.1.2    OSPLookup
3.1.3    OSPNext
3.1.4    OSPFinish
3.2      Build with OSP Support
3.3      Configure with OSP Support
3.3.1    osp.conf
3.3.2    zapata/sip/iax.conf
3.3.3    extensions.conf

Asterisk is a trademark of Digium, Inc.
TransNexus and OSP Secured are trademarks of TransNexus, Inc.

1 Introduction
  This document provides instructions on how to build and configure Asterisk 
  V1.4 with the OSP Toolkit to enable secure, multi-lateral peering. The OSP 
  Toolkit is an open source implementation of the OSP peering protocol and is 
  freely available from www.sipfoundry.org.  The OSP standard defined by the 
  European Telecommunications Standards Institute (ETSI TS 101 321) 
  www.esti.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://list.sipfoundry.org/mailman/listinfo/osp. 

2 OSP Toolkit
  Please reference the OSP Toolkit document "How to Build and Test the OSP 
  Toolkit" available from www.sipfoundry.org/OSP/OSPclient .  

2.1 Build OSP Toolkit
  The software listed below is required ti 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/ActivePerl. 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.  
  Open source OSP servers are available from www.sipfoundry.org/osp, a free 
  commercial OSP server may be downloaded from www.transnexus.com and an OSP 
  server osptestserver.transnexus.com is freely available on the internet for 
  testing for testing. Please contact support@transnexus.com for testing access
  to osptestserver.transnexus.com.

2.1.1 Unpacking the Toolkit
  After downloading the OSP Toolkit (version 3.3.4 or later release) from 
  www.sipfoundry.org, perform the following steps in order:
  1) Copy the OSP Toolkit distribution into the directory where it will reside,
  say /usr/src. 
  2) Un-package the distribution file by executing the following command: 
    gunzip -c OSPToolkit-###.tar.gz | tar xvf -
    Where ### is the version number separated by underlines. For example, if 
    the version is 3.3.4, then the above command would be: 
    gunzip -c OSPToolkit-3_3_4.tar.gz | tar xvf -
  A new directory (TK-3_3_4-20051103) will be created within the same directory
  as the tar file.
  3) Go to the TK-3_3_4-20051103 directory by running this command:
    cd TK-3_3_4-20051103
  Within this directory, you will find directories and files similar to what is
  listed below if the command "ls -F" is executed):
    ls -F
    enroll/
    RelNotes.txt        lib/
    README.txt          license.txt
    bin/                src/
    crypto/             test/
    include/

2.1.2 Preparing to build the OSP Toolkit
  4) Compile OpenSSL according to the instructions provided with the OpenSSL 
  distribution (You would need to do this only if you don'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, 4~6 are not necessary.

2.1.3 Building the OSP Toolkit
  7) Optionally, change the install directory of the OSP Toolkit. Open the 
  Makefile in the /usr/src/TK-3_3_4-20051103/src directory, look for the 
  install path variable - 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. Otherwise, it may case that the 
  Asterisk does not support the OSP protocol.
  8) From within the OSP Toolkit directory (/usr/src/TK-3_3_4-20051103), start 
  the compilation script by executing the following commands:
    cd src
    make clean; make build

2.1.4 Installing the OSP Toolkit
  The header files and the library of the OSP Toolkit should be installed. 
  Otherwise, you must specify the OSP Toolkit path for the Asterisk.
  9) Use the same script to install the Toolkit.
    make install
  The make script is also used to install the OSP Toolkit header files and the 
  library into the INSTALL_PATH specified in the Makefile. 
  Note: Please make sure you have the rights to access the INSTALL_PATH 
  directory. For example, in order to access /usr/local directory, normally, 
  you should be root.
  By default, the OSP Toolkit is compiled in the production mode. The following
  table identifies which default features are activated with each compile 
  option:
    Default Feature                Production    Development
    Debug Information Displayed    No            Yes
  The "Development" option is recommended for a first time build. The CFLAGS 
  definition in the Makefile must be modified to build in development mode.  

2.1.5 Building the Enrollment Utility
  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 and 
  OSP client and an OSP server. Please see the document "Device Enrollment" at 
  www.sipfoundry.org/OSP/OSPclient for more information about the enroll 
  application.
  10) From within the OSP Toolkit directory (/usr/src/TK-3_3_4-20051103), 
  execute the following commands at the command prompt:
    cd enroll
    make clean; make linux
  Compilation is successful if there are no errors anywhere in the compiler 
  output. The enroll program is now located in the 
  /usr/src/TK-3_3_4-20051103/bin directory. By this point, a fully functioning 
  OSP Toolkit should have been successfully built.

2.2 Obtain Crypto Files
  The OSP module in Asterisk requires three crypto files containing 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/key.  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 the Asterisk OSP module with an OSP server to obtain the crypto files.
  Documentation explaining how to use the enroll.sh script (Device Enrollment) 
  to enroll with an OSP server is available at 
  www.sipfoundry.org/OSP/ospclient.  Copy the files file generated by the 
  enrollment process to the Asterisk configuration 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 of www.sipfoundry.org or send an e-mail to 
  support@transnexus.com.
  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 - cacert_#.pem, certreq.pem, localcert.pem, and pkey.pem. The '#'
  in the cacert file name is used to differentiate the ca certificate file 
  names for the various SP'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 - cacert_0.pem and 
  cacert_1.pem, one for each SP. The example below shows the usage when the 
  client is registering with osptestserver.transnexus.com. If all goes well, 
  the following text will be displayed. The gray boxes indicate required input.
    ./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
    X509 CertInfo context is null pointer
    Unable to get Local Certificate
    depth=0 /CN=osptestserver.transnexus.com/O=OSPServer
    verify error:num=18:self signed certificate
    verify return:1
    depth=0 /CN=osptestserver.transnexus.com/O=OSPServer
    verify return:1
    The certificate request was successful.
    Error Code returned from localcert command : 0
  The files generated should be copied to the /var/lib/asterisk/key 
  directory. 
  Note: The script enroll.sh requires AT&T korn shell (ksh) or any of its 
  compatible variants. The /usr/src/TK-3_3_4-20051103/bin directory should be 
  in the PATH variable. Otherwise, enroll.sh cannot find the enroll file.

3 Asterisk

3.1 OSP Support Implementation
  In Asterisk, all OSP support is implemented as dial plan functions.

3.1.1 OSPAuth 
  OSP token validation function.
  Input:
  * OSPPEERIP: last hop IP address
  * OSPINTOKEN: inbound OSP token
  * provider: OSP service provider configured in osp.conf. If it is empty, 
  default provider is used.
  * priority jump
  Output:
  * OSPINHANDLE: inbound OSP transaction handle
  * OSPINTIMELIMIT: inbound call duration limit
  * OSPAUTHSTATUS: OSPAuth return value. SUCCESS/FAILED/ERROR

3.1.2 OSPLookup
  OSP lookup function.
  Input:
  * OSPPEERIP: last hop IP address
  * OSPINHANDLE: inbound OSP transaction handle
  * OSPINTIMELIMIT: inbound call duration limit 
  * exten: called number
  * provider: OSP service provider configured in osp.conf. If it is empty, 
  default provider is used.
  * priority jump
  Output:
  * OSPOUTHANDLE: outbound transaction handle
  * OSPTECH: outbound protocol
  * OSPDEST: outbound destination
  * OSPCALLING: outbound calling number
  * OSPOUTTOKEN: outbound OSP token
  * OSPRESULTS: number of remain destinations
  * OSPOUTTIMELIMIT: outbound call duration limit
  * OSPLOOKUPSTATUS: OSPLookup return value. SUCCESS/FAILED/ERROR

3.1.3 OSPNext
  OSP lookup next function.
  Input:
  * OSPINHANDLE: inbound transaction handle
  * OSPOUTHANDLE: outbound transaction handle
  * OSPINTIMELIMIT: inbound call duration limit 
  * OSPRESULTS: number of remain destinations
  * cause: last destination disconnect cause
  * priority jump
  Output:
  * OSPTECH: outbound protocol
  * OSPDEST: outbound destination
  * OSPCALLING: outbound calling number
  * OSPOUTTOKEN: outbound OSP token
  * OSPRESULTS: number of remain destinations
  * OSPOUTTIMELIMIT: outbound call duration limit
  * OSPNEXTSTATUS: OSPLookup return value. SUCCESS/FAILED/ERROR

3.1.4 OSPFinish
  OSP report usage function.
  Input:
  * OSPINHANDLE: inbound transaction handle
  * OSPOUTHANDLE: outbound transaction handle
  * OSPAUTHSTATUS: OSPAuth return value
  * OSPLOOKUPTSTATUS: OSPLookup return value
  * OSPNEXTSTATUS: OSPNext return value
  * cause: last destination disconnect cause
  * priority jump
  Output:
  * OSPFINISHSTATUS: OSPLookup return value. SUCCESS/FAILED/ERROR

3.2 Build with OSP Support
  If the OSP Toolkit is installed in the default install directory, /usr/local,
  no additional configuration is required. If the OSP Toolkit is installed in 
  another directory, say /myosp, Asterisk must be configured with the location 
  of the OSP Toolkit.
    --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 results Asterisk not 
  supporting the OSP protocol.
  Now, you can compile Asterisk according to the instructions provided with the
  Asterisk distribution.

3.3 Configure with OSP Support

3.3.1 osp.conf
  ;
  ; Open Settlement Protocol Sample Configuration File
  ;
  ; This file contains configuration of providers that
  ; are used by the OSP subsystem of Asterisk.  The section
  ; "general" is reserved for global options.  Each other 
  ; section declares an OSP Provider.  The provider "default"
  ; is used when no provider is otherwise specified.
  ;
  [general]
  ;
  ; Should hardware acceleration be enabled?  May not be changed
  ; on a reload.
  ;
  accelerate=no
  ;
  ; Defines the token format that Asterisk can validate. 
  ; 0 - signed tokens only 
  ; 1 - unsigned tokens only 
  ; 2 - both signed and unsigned
  ; The defaults to 0, i.e. the Asterisk can validate signed tokens only.
  ;
  tokenformat=0
  ;
  [default]
  ;
  ; All paths are presumed to be under /var/lib/asterisk/keys unless
  ; the path begins with '/'
  ;
  ; Specify the private keyfile.  If unspecified, defaults to the name
  ; of the section followed by "-privatekey.pem" (e.g. default-privatekey.pem)
  ;
  privatekey=pkey.pem
  ;
  ; Specify the local certificate file.  If unspecified, defaults to
  ; the name of the section followed by "-localcert.pem"
  ;
  localcert=localcert.pem
  ;
  ; Specify one or more Certificate Authority keys.  If none are listed,
  ; a single one is added with the name "-cacert.pem"
  ;
  cacert=cacert_0.pem
  ;
  ; Specific parameters can be tuned as well:
  ;
  ; maxconnections: Max number of simultaneous connections to the provider (default=20)
  ; retrydelay:     Extra delay between retries (default=0)
  ; retrylimit:     Max number of retries before giving up (default=2)
  ; timeout:        Timeout for response in milliseconds (default=500)
  ;
  maxconnections=20
  retrydelay=0
  retrylimit=2
  timeout=500
  ;
  ; List all service points for this provider
  ;
  ;servicepoint=http://osptestserver.transnexus.com:1080/osp
  servicepoint=http://OSP server IP:1080/osp
  ;
  ; Set the "source" for requesting authorization
  ;
  ;source=foo
  source=[host IP]
  ;
  ; Set the authentication policy.  
  ; 0 - NO 
  ; 1 - YES
  ; 2 - EXCLUSIVE
  ; Default is 1, validate token but allow no token.
  ;
  authpolicy=1

3.3.2 zapata/sip/iax.conf
  There is no configuration required for OSP.

3.3.3 extensions.conf
  An Asterisk box can be configured as OSP source/destination gateway or OSP proxy.

3.3.3.1 OSP Source Gateway
  [PhoneSrcGW]
  ; Set calling number if necessary
  exten => _XXXX.,1,Set(CALLERID(numner)=CallingNumber)
  ; OSP lookup using default provider, if fail/error jump to 2+101
  exten => _XXXX.,2,OSPLookup(${EXTEN}||j)
  ; Set calling number which may be translated 
  exten => _XXXX.,3,Set(CALLERID(number)=${OSPCALLING})
  ; Dial to destination, 60 timeout, with call duration limit
  exten => _XXXX.,4,Dial(${OSPTECH}/${OSPDEST},60,oL($[${OSPOUTTIMELIMIT}*1000]))
  ; Wait 3 seconds
  exten => _XXXX.,5,Wait,3
  ; Hangup
  exten => _XXXX.,6,Hangup
  ; Deal with OSPLookup fail/error
  exten => _XXXX.,2+101,Hangup
  ; OSP report usage
  exten => h,1,OSPFinish(${HANGUPCAUSE})
  3.3.3.2 OSP Destination Gateway
  [PhoneDstGW]
  ; Get peer IP
  exten => _XXXX.,1,Set(OSPPEERIP=${SIPCHANINFO(peerip)})
  ; Get OSP token
  exten => _XXXX.,2,Set(OSPINTOKEN=${SIP_HEADER(P-OSP-Auth-Token)})
  ; Validate token using default provider, if fail/error jump to 3+101
  exten => _XXXX.,3,OSPAuth(|j)
  ; Ringing
  exten => _XXXX.,4,Ringing
  ; Wait 1 second
  exten => _XXXX.,5,Wait,1
  ; Dial phone, timeout 15 seconds, with call duration limit
  exten => _XXXX.,6,Dial(${DIALOUTANALOG}/${EXTEN:1},15,oL($[${OSPINTIMELIMIT}*1000]))
  ; Wait 3 seconds
  exten => _XXXX.,7,Wait,3
  ; Hangup
  exten => _XXXX.,8,Hangup
  ; Deal with OSPAuth fail/error
  exten => _XXXX.,3+101,Hangup
  ; OSP report usage
  exten => h,1,OSPFinish(${HANGUPCAUSE})
  3.3.3.3 Proxy
  [GeneralProxy]
  ; Get peer IP
  exten => _XXXX.,1,Set(OSPPEERIP=${SIPCHANINFO(peerip)})
  ; Get OSP token
  exten => _XXXX.,2,Set(OSPINTOKEN=${SIP_HEADER(P-OSP-Auth-Token)})
  ; Validate token using default provider, if fail/error jump to 3+101
  exten => _XXXX.,3,OSPAuth(|j)
  ; OSP lookup using default provider, if fail/error jump to 4+101
  exten => _XXXX.,4,OSPLookup(${EXTEN}||j)
  ; Set calling number which may be translated 
  exten => _XXXX.,5,Set(CALLERID(number)=${OSPCALLING})
  ; Dial to 1st destination, 60 timeout, with call duration limit
  exten => _XXXX.,6,Dial(${OSPTECH}/${OSPDEST},24,oL($[${OSPOUTTIMELIMIT}*1000]))
  ; OSP lookup next, if fail/error jump to 7+101
  exten => _XXXX.,7,OSPNext(${HANGUPCAUSE}||j)
  ; Set calling number which may be translated 
  exten => _XXXX.,8,Set(CALLERID(number)=${OSPCALLING})
  ; Dial to 2nd destination, 60 timeout, with call duration limit
  exten => _XXXX.,9,Dial(${OSPTECH}/${OSPDEST},25,oL($[${OSPOUTTIMELIMIT}*1000]))
  ; OSP lookup next, if fail/error jump to 10+101
  exten => _XXXX.,10,OSPNext(${HANGUPCAUSE}||j)
  ; Set calling number which may be translated 
  exten => _XXXX.,11,Set(CALLERID(number)=${OSPCALLING})
  ; Dial to 3rd destination, 60 timeout, with call duration limit
  exten => _XXXX.,12,Dial(${OSPTECH}/${OSPDEST},26,oL($[${OSPOUTTIMELIMIT}*1000]))
  ; Hangup
  exten => _XXXX.,13,Hangup
  ; Deal with OSPAuth fail/error
  exten => _XXXX.,3+101,Hangup
  ; Deal with OSPLookup fail/error
  exten => _XXXX.,4+101,Hangup
  ; Deal with 1st OSPNext fail/error
  exten => _XXXX.,7+101,Hangup
  ; Deal with 2nd OSPNext fail/error
  exten => _XXXX.,10+101,Hangup
  ; OSP report usage
  exten => h,1,OSPFinish(${HANGUPCAUSE})
