Communicate with the JUNOS Remote API

May 13, 2013 How To

Remotely Executing Commands on JUNOS

Those who are familiar with Juniper and their software known as JUNOS, may not know about the extendability of the platform using SLAX. You can read about SLAX on Juniper’s website.

SLAX is a programming language based on XSLT, which allows you to access the API on the JUNOS platform, which ranges from configuration to executing commands via the CLI and conditionally controlling the output. This SinatraNetworks post has a great security-focused SLAX script called op srx-monitor and references official documentation from Juniper Networks.

To extend SLAX and JUNOS even further, Juniper’s Phil Shafer released Juise.

JUISE takes the abilities provided by the scripting facility of JUNOS and moves it into the open source world, where a script can run on a remote box, accessing JUNOS resources over the NETCONF (or JUNOScript) API. Initially this will be an excellent environment for creating and debugging scripts, but for many users, it may become their “normal” scripting environment.

The following will document how to configure and install juise and it’s dependencies.

Install lib-ssh2 Dependencies

Honestly, you can do without this one, but it does add some more features. Libssh2 is an open-source SSH2 library with an amazingly easy-to-use API. For the sake of consistency for the rest of the post, we will configure this is a general location so other packages and depend on it.

You can install it by doing the following:

tar xvzf libssh2-1.4.4-20130507.tar.gz
cd libssh2-1.4.4-20130507/
./configure --prefix=/usr/local/ssh2 --with-openssl
sudo make install

Install libslax Dependency

libslax is the library surrounding Juniper’s SLAX language. libslax will allow you to execute, debug and validate syntax of SLAX scripts. To install it, complete the following:

tar xvzf libslax-0.14.7.tar.gz
cd libslax-0.14.7/
./configure --with-libcurl-prefix=/usr --with-libxslt-prefix=/usr --enable-readline --prefix=/usr/local/slax
sudo make install

Install Juise

Follow the following steps to install Juise. It depends on the previous libraries which we built and installed:

tar xvzf juise-0.3.21.tar.gz
cd juise-0.3.21/
./configure --prefix=/usr/local/juise --with-pcre --with-libxml-prefix=/usr --with-libslax-prefix=/usr/local/slax --with-libxslt-prefix=/usr --with-libssh2-prefix=/usr/local/ssh2
make install

To add Juise to your $PATH, run: export PATH=$PATH:/usr/local/juise/bin. You can also add this to .bashrc or /etc/profile so Juise is available across shell sessions.

Putting it all together

To execute a command with Juise, you can run juise test.slax.

test.slax :

version 1.2; 

/ *************************************************** / 
/* Example SLAX Script */ 
/* Written by Mike Mackintosh */ 
/* */
/* Credit To Mike Stone */
/* */
/ *************************************************** / 
ns junos = "*/junos"; 
ns xnm = ""; 
ns jcs = ""; 
ns ext = ""; 
ns str = ""; 
ns exsl extension = ""; 
ns exsl = ""; 
ns func extension = ""; 
ns date = ""; 

import "junos.xsl";

param $host-file; 
param $env;

mvar $result; 
mvar $connection; 
mvar $hostname; 
mvar $password;

match / {

        /* grab remote connection information */
        if (not ($host-file))
                     expr jcs:output("\n\nUsage: juise example.slax [required parameter] [options]\n");
                     expr jcs:output("\tRequired Parameter, specify only one]");
                     expr jcs:output("\t-------------------------------------");
                     expr jcs:output("\tremote-host <ip address> :: Check a single device");
                     expr jcs:output("\thost-file <filename> :: Check all hosts provided in <filename>\n\n");
                     <xsl:message terminate='yes'> "\n\n\n\n";

        /* if not comparing files, then process the remote-host or host-file parameters */
        var $remote-user = jcs:get-input("Username: ");

        var $pwd-prompt = "Password: ";
        var $password = jcs:get-secret( $pwd-prompt);

        if ($host-file)
             var $hosts = document($host-file);
             var $host-list = jcs:split("\n",$hosts);
                     if (. != "")
                         set $connection = jcs:open(.,$remote-user,$password);

                         if (not (jcs:empty($connection)))
                           { /* valid connection */

                             var $config = jcs:execute($connection, "get-configuration" );
                             expr jcs:output( $config );

                             expr jcs:close($connection);

                                expr jcs:output(concat("Could not connect to ", .));
                              } /* inner else */
                           } /* outer else */

         expr jcs:output( "\n\nDone processing checks.\nExiting.");
      } /* op script result */
   } /*match */

devices-list.txt :

<?xml version="1.0"?>

Once you create the two files above, you can execute them with this command:

juise test.slax host-file devices-list.txt

This script will connect to each device and grab the configuration and return it to the CLI. Since SLAX is XML-based being XSLT, your tags will not be displayed in the output, only the content.

This really opens up the door to some great possibilities.

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