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NETCONF Perl client

   Contents
     * Abstract
     * Supported Platforms
     * Prerequisites
     * Installation
     * Running the Sample Scripts
     * Troubleshooting

Abstract

The NETCONF API provides mechanisms to install, manipulate, and delete the configuration of network devices. The NETCONF API uses an Extensible markup Language (XML) based data encoding for the configuration data as well as operations and messages defined in the API.

The Net::Netconf::Manager module provides an object-oriented interface for communicating with the NETCONF server so you can start using the NETCONF API quickly and easily. There are several modules in this library but client applications directly invoke the Manager object only. When the client application creates a Net::Netconf::Manager object, it specifies a router name and the login name to use when accessing the router (which determines the client application's access level).

The following code segment shows how to use the Net::Netconf::Manager object to request information from a routing platform. This example invokes the query called get_chassis_inventory.

 # Step 1: set up the query
 // RPC tag <get-chassis-inventory> should be querried as below
 my $query = "get_chassis_inventory";
 my %queryargs = ( 'detail' => 'True' );
 # Step 2: Create a Netconf Manager object and connect to Networks routing platform
 my %deviceinfo = (
  access => "ssh",
  login => "johndoe",
  password => "secret",
  hostname => "router11"
  );
  my $jnx = new Net::Netconf::Manager(%deviceinfo);
  unless ( ref $jnx ) {
         croak "ERROR: $deviceinfo{hostname}: failed to connect.\n";
  }
 # Step 3: send the query and receive a reply
 my $res = $jnx->$query( %queryargs );
 # Step 4: check for error
 if ($jnx->has_error) {
      croak "ERROR: in processing request \n $jnx->{request} \n";
  } 
  else {
 # Step 5: do something with the result
  }
 # Step 6: always disconnect from the server when you're done
 $jnx->disconnect();

Supported Platforms

The current version of this module has been tested on the following platforms. Later releases may support additional platforms.

 * Ubuntu 12.04LTS 
 * Fedora 15 i686
 * Centos-6.5-i386
    

Prerequisites

Following are the Prerequisites for using this API:
   1. Net::SSH2
   2. File::Which
   3. XML::LibXML

Also make sure that your system has libxml2 and libxml2-dev library. If not then either install it from source package in ubuntu website or by using apt-get. For more info look at the Troubleshooting

Installation

Make sure Perl is installed. If necessary, see Installation of Perl.
% which perl
% perl -v
The NETCONF Perl API requires version 5.6.1 or later of the perl executable. Verify that you are running 
that version of the perl executable. If not, check your PATH or install the latest release of perl.
        
    There are two ways to install Net::Netconf Module in your system:
    1. Using CPAN
    2. Using source code in github
Note: If you are using cpan command then you don't have to install prerequisites, they will automatically be
installed by cpan        
 
    Using CPAN
    -----------------------------------------------------------------------------------------
    Before installing using cpan, make sure your system has cpan, if not then install it either by "apt-get 
    install cpan" or "yum install cpan" (according to the OS you are using)
    1. To install using CPAN make sure your system has C dependencies, i.e. libxml2 and libxml2-dev package.
    2. After installing these two packages in your system install Net::Netconf module by using CPAN command 
    "cpan Net::Netconf". 
   
    Sometimes cpan command gives error then try installing using "cpanm" command. First install cpanm in your 
    system by "apt-get install cpanminus"  and then install this module by "cpanm Net::Netconf"
    
    Using Source code in github
    --------------------------------------------------------------------------------------------
    Instructions for UNIX Systems
    Install the prerequisites of Perl modules. 
    Following are the prerequites
    1. Net::SSH2
    2. File::Which
    3. XML::LibXML
    
    Steps to install Prerequisites in Ubuntu12.04LTS :
    1. cpan Net::SSH2
    2. cpan File::Which
    3. cpan XML::LibXML
        
    After successfully installing Prerequisites install NETCONF PERL CLIENT
      
    1. Download the Perl NETCONF zip archive from Juniper's Repository in github 
    2. Unzip the archive.
        % unzip netconf-Perl-master.zip
    3. Change to the NETCONF directory.
        % cd netconf-perl-master
    4. Create Net::Netconf Makefile.
       If installing Net::Netconf::Manager under the standard directory
        (by default it is /usr/local/lib):
        [/my/netconf-perl-master]% perl Makefile.PL
    5. Install the Net::Netconf module.
        [/my/netconf-perl-master]% make
        [/my/netconf-perl--master]% make install
        (to run make install user should have root permission)
        

Running the Sample Scripts

The NETCONF Perl distribution includes sample scripts that demonstrate how to use NETCONF to retrieve and change the configuration of a Networks routing platform. The samples reside in the netconf-perl-n.n/examples directory.

Reading configuration: System Information This example sends a <get-system-information> request to the Networks routing platform and displays the result to the standard output.It also shows how to parse reply from server

Script: get_system_information.pl

        use Net::Netconf::Manager;
        print "Enter hostname\n";
        my $hostname = <>;
        print "Enter username\n";
        my $login= <>;
        print "Enter password\n";
        my $pass = <>;
        chomp($hostname);
        chomp($login);
        chomp($pass);
        $jnx = new Net::Netconf::Manager( 'access' => 'ssh',
                      'login' => $login,
                      'password' => $pass,
                      'hostname' => $hostname);
        if(! $jnx ) {
              print STDERR "Unable to connect to Junos device \n";
              exit 1;
         }
         print "Connection established: " . $jnx->get_session_id . "\n";
         my $reply=$jnx->get_system_information();
         if ($jnx->has_error) {
         print "ERROR: in processing request\n";
         # Get the error
         my $error = $jnx->get_first_error();
         $jnx->print_error_info(%$error);
         exit 1;
         }
 	  print "Server request: \n $jnx->{'request'}\n Server response: \n $jnx->{'server_response'} \n";

         # this parsing is specifically for <get-system-information> tag
         # you can write your own application in similar way
         #parsing reply from server
         my $config= $jnx->get_dom();
         $res= $config->getElementsByTagName("hardware-model")->item(0)->getFirstChild->getData;
         $res2= $config->getElementsByTagName("os-name")->item(0)->getFirstChild->getData;
         $res3= $config->getElementsByTagName("host-name")->item(0)->getFirstChild->getData;
         print "\nhardware information  ". $res ."\n";
         print "os-name  " .$res2 . "\n";
         print "host-name  ". $res3. "\n";
         $jnx->disconnect();

Output:
Run netconf-perl script:

perl <script_name>
priyal@priyal:~/Desktop$ perl get_system_information.pl
Enter hostname: device1
Enter username: foo
Enter password: passwd123

Server request: 
 <rpc message-id='1'>
  <get-system-information/>
</rpc>

 Server response: 
<rpc-reply xmlns="urn:ietf:params:xml:ns:netconf:base:1.0" xmlns:junos="http://xml.juniper.net/junos/15.2I0/junos" message-id='1'>
<system-information>
<hardware-model>olive</hardware-model>
<os-name>junos</os-name>
<os-version>15.2I20151211</os-version>
<host-name>device1</host-name>
</system-information>
</rpc-reply>

hardware information:  olive
os-name:  junos
host-name: device1

Troubleshooting (Ubuntu12.04LTS or higher version)

1. Installing libxml2 and libxml2-dev 
   - Install using apt-get
        apt-get install libxml2
        apt-get install libxml2-dev
   - Installing from source code
     Download your system specific package from http://packages.ubuntu.com/
     For Precise(12.04 LTS) download its .dpkg packages
     For libxml2: http://packages.ubuntu.com/precise/libxml2
     For libxml2-dev : http://packages.ubuntu.com/precise/libxml2-dev
     
     Install these packages in your system :
        dpkg -i libxml2_2.7xyz__.dpkg
        dpkg -i libxml2-dev_2xyz__.dpkg
        
  Note : Libxml2 and libxml2-dev should be of same version
  
If you get libxml related error even after installing its dependency like libxml2 and libxml2-dev then try 
below  command
        apt-get install libxml-libxml-perl
        
Sometimes you may get error like "Checking for ability to link against xml2...no " while installing LibXML then 
use this command
      sudo apt-get install zlib1g-dev
      
2. For error related to Net::SSH2
   Sometimes you may get error like,
          fatal error: openssl/crypto.h: No such file or directory
          #include <openssl/crypto.h>
                        ^
          compilation terminated.
          make: *** [SSH2.o] Error 1
  then use then command:
  sudo apt-get install libssl-dev
  
3. For YAML related Errors
   Sometimes you may get that yaml is not installed then run following commands:
         apt-get install libyaml-appconfig-perl
         apt-get install libconfig-yaml-perl

3. For libz errors like:
         /usr/bin/ld: /usr/local/lib/libz.a(crc32.o): relocation R_X86_64_32 against `.rodata' can not be used when 
           making a shared object; recompile with -fPIC
         /usr/local/lib/libz.a: could not read symbols: Bad value
     try installing from source code:
         download libz source code, https://google-desktop-for-linux-mirror.googlecode.com/files/zlib-1.2.3.tar.gz
         according to platform u are using.
         open Makefile and add -fPIC in cflag, (smth like: CFLAGS=-O3 -DUSE_MMAP -fPIC)
         then compile it:
         ./configure
         make test
         make install
    
4. For cpan related errors:
   While installing some files using cpan, for example "cpan File::Which" you may get error like checksum mismatch
   for distribution, then try installing that package using "cpanm"
   First install cpanm in your system by:
   apt-get install cpanminus
   and then install desired package by using cpanm, for example:
   cpanm File::Which
   
   While installing perl dependency using cpan, if you get errors like "XML::NamespaceSupport package not found" or
   unmet dependency then first install that package using cpan / cpanm and then install your desired package.
   you can also try installing by force :
   apt-get -f install
         

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