Kerberos for Node.js

krb5 is a Node.js native binding for Kerberos. It is a Node.js implementation of Kerberos client tools:

• kinit (keytab, or password): retrieve initial credentials;
• kdestroy: destroy a credential cache;
• spnego: generate a SPNEGO token.

It uses the MIT Kerberos native library.
SPNEGO is a GSS mechanism to authenticate through HTML requests.

Installation

To build this module, you need MIT Kerberos library. Refer to the section corresponding to your operating system.

Archlinux

pacman -S krb5
npm install krb5

RHEL/Centos

yum install -y krb5-devel
npm install krb5

Ubuntu

apt-get install -y libkrb5-dev
npm install krb5

MacOS

brew install krb5
npm install krb5

Windows

To compile this library in windows, you need a complete visual studio compile chain, please refer to this webpage. If you have a 32 bit OS, please delete binding.gyp and rename _binding32.gyp before install.

Manual compilation of MIT Kerberos

Follow these instructions if you wish to manually install MIT Kerberos (in case your distribution packet manager does not have a corresponding package for example).

wget https://kerberos.org/dist/krb5/1.16/krb5-1.16.1.tar.gz
tar -xzf krb5-1.16.1.tar.gz 
cd krb5-1.16.1/src
./configure
make
sudo make install

The latest version downloaded with wget can be found here.

Compiling from the source of MIT Kerberos requires python2, make, gcc (g++), bison.

If you want to install MIT Kerberos in another directory (default is "/usr/local"), specify a --prefix option to ./configure.

If kerberos is installed in a directory not included in include and/or library path (if you have manually compiled kerberos in a specific directory for example), please modify the binding.gyp present in the package root folder with the following properties:

{
  'targets': [{
    'target_name': 'krb5',
    'include_dirs': [
      '/path/to/kerberos/include/dir/',
      '/path/to/kerberos_gssapi/include/dir/'],
    'libraries': [
      '/path/to/libkrb5', 
      '/path/to/libgssapi_krb5']
  }]
}

Usage

Quick example

• Retrieve a SPNEGO token for a service

In this example we want to retrieve a token to access a REST API of the service HBase, located on the host m01.krb.local .

// Get the initial credentials using a keytab
krb5.kinit({
  principal: 'hbase/m01.krb.local',
  keytab: '/tmp/hbase.service.keytab',
  realm: 'KRB.LOCAL',
}, function (err, ccname) {
  if (err) {
    console.log(err)
  } else {
    console.log('Credentials saved in', ccname)
    // Get the SPNEGO token
    krb5.spnego({
      service_fqdn: 'm01.krb.local'
    }, function (err, token) {
      if (err) {
        console.log(err)
      } else {
        console.log('SPNEGO token :', token)
      }
    })
  }
});

You can also use promises.

krb5.kinit({
  principal: 'hbase/m01.krb.local',
  keytab: '/tmp/hbase.service.keytab',
  realm: 'KRB.LOCAL',
}).then(function (ccname) {
  console.log('Credentials saved in', ccname)
  return krb5.spnego({
    hostbased_service: '[email protected]'
  })
}).then(function (token) {
  console.log('SPNEGO token :', token)
}).catch(function (err) {
  console.log(err)
})

For more example, see the samples and test directories.

Functions

kinit(options, callback) : retrieve initial credentials (Ticket Granting Ticket)

Options:

• principal
  Kerberos principal username@REALM or username. If realm is given, overrides the realm option.

• password / keytab
  One of both should be given for authentication.

• realm (optionnal)
  Kerberos realm (usually capitalized domain name). If this is not specified, use the default realm from /etc/krb5.conf.

• ccname (optionnal)
  Credential cache location. If this is not specified, default path is taken from environment variable KRB5CCNAME, then from /etc/krb5.conf.

Callback parameters:

• err
  Should be undefined. Otherwise it contains an error message.

• ccname
  Credential path location used to store initial credentials.

spnego(options, callback) : retrieve a SPNEGO token.

In order to retrieve a SPNEGO token to access a service, you first need an initial ticket (TGT) which you can get with kinit.

Options:

• hostbased_service or service_fqdn
  Hostbased service should be of the form service@fqdn. If you only pass the fully qualified domain name fqdn, it will default to HTTP@fqdn.
  It will be resolved to the corresponding principal service/fqdn@REALM by the GSS-API. To use the principal directly, use the service_principal option instead.

• service_principal
  Principal of the service.

• ccname (optionnal)
  Location of the credential cache storing the initial ticket. If not specified, default path is taken.

Callback parameters:

• err
  Should be undefined. Otherwise contains GSS API major error code.

• token
  The SPNEGO token to access the service. It can then be added to the header of the HTTP request Authorization: Negociate {token}

kdestroy (options, callback) : destroys credential cache

Options:

• ccname (optionnal)
  Credential cache location. If this is not specified, default path is taken from environment variable KRB5CCNAME, then from /etc/krb5.conf.

Callback parameters:

• err
  Should be undefined. Otherwise it contains an error message.

Run the the tests

To run the tests in a container:

cd docker && ./run_tests $os

Available $os: archlinux / ubuntu / centos7

To test this module locally, run the KDC and REST dockers, and use the corresponding krb5.conf (bcakup your own if you need it later):

cd docker
docker-compose up -d kerberos
docker-compose up -d rest
sudo mv /etc/krb5.conf /etc/krb5.conf.backup
sudo cp /tmp/krb5_test/krb5.conf /etc/krb5.conf
sudo npm test

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