Most documentation focuses on syncing external directories to Google Workspace (formerly G Suite), but many sysadmins need the opposite - leveraging Google's userbase for external server authentication. While Google doesn't natively provide full LDAP/AD services, we can bridge this gap through strategic configuration.

# Required components:
- Google Workspace Enterprise subscription (LDAP API access)
- Secure LDAP service enabled in Admin Console
- Server with LDAP client libraries (OpenLDAP, SSSD, etc.)
- Port 636/TCP open for LDAPS

Google's Secure LDAP service provides partial LDAPv3 compatibility. Configure it via:

1. Enable in Admin Console > Security > Secure LDAP
2. Create service account with LDAP privileges
3. Generate JSON credentials for authentication

# /etc/sssd/sssd.conf
[domain/google]
id_provider = ldap
auth_provider = ldap
ldap_uri = ldaps://ldap.google.com
ldap_search_base = dc=yourdomain,dc=com
ldap_tls_cacert = /etc/ssl/certs/ca-certificates.crt
ldap_default_bind_dn = uid=service_account,dc=yourdomain,dc=com
ldap_default_authtok_type = password
ldap_default_authtok = (service_account_password)

For Active Directory integration, consider:

• Google Cloud Directory Sync (GCDS) with read-only LDAP connector
• Third-party tools like Okta or JumpCloud as middleware
• Custom PowerShell sync script example:

# PowerShell AD sync snippet
Import-Module ActiveDirectory
$googleUsers = Invoke-RestMethod -Uri "https://admin.googleapis.com/admin/directory/v1/users" -Headers $headers
foreach ($user in $googleUsers.users) {
    New-ADUser -Name $user.primaryEmail -GivenName $user.name.givenName -Surname $user.name.familyName -UserPrincipalName $user.primaryEmail
}

When native LDAP won't suffice:

// OAuth 2.0 authentication flow example
const {google} = require('googleapis');
const oauth2Client = new google.auth.OAuth2(
  CLIENT_ID,
  CLIENT_SECRET,
  REDIRECT_URL
);

// Generate authentication URL
const scopes = [
  'https://www.googleapis.com/auth/admin.directory.user.readonly'
];
const url = oauth2Client.generateAuthUrl({
  access_type: 'offline',
  scope: scopes
});

While most documentation focuses on integrating external directories with Google Workspace (formerly G Suite), many administrators face the opposite need - leveraging Google's userbase as an authoritative source for other systems. The scenario involves:

• Existing Google Workspace users needing access to on-premise servers
• Internal applications requiring directory services integration
• Maintaining a single source of truth in the cloud

Google doesn't natively provide LDAP or Active Directory services, but we can bridge this gap through several approaches:

// Sample Python snippet for Google Directory API access
from google.oauth2 import service_account
from googleapiclient.discovery import build

SCOPES = ['https://www.googleapis.com/auth/admin.directory.user.readonly']
SERVICE_ACCOUNT_FILE = 'service-account.json'

credentials = service_account.Credentials.from_service_account_file(
        SERVICE_ACCOUNT_FILE, scopes=SCOPES)

delegated_credentials = credentials.with_subject('admin@domain.com')
service = build('admin', 'directory_v1', credentials=delegated_credentials)

results = service.users().list(customer='my_customer', maxResults=10,
    orderBy='email').execute()
users = results.get('users', [])

Option 1: LDAP Proxy Service

Tools like:

• G Suite LDAP Bridge (third-party)
• Apache Directory Studio with custom connector
• Identity Provider middleware (PingFederate, Okta)

Option 2: SCIM Protocol Implementation

// Node.js SCIM server example
const scim = require('scim2-node');

const server = scim.createServer({
    getUser: async (id) => {
        // Query Google Directory API
        return transformedUserObject;
    },
    getUsers: async (filter) => {
        // Implement pagination and filtering
    }
});

server.listen(8080);

When building the integration:

1. Token management for API rate limits
2. Attribute mapping between systems
3. Caching strategies for performance
4. Security implications of proxy services

For a Kubernetes environment:

# Deployment.yaml snippet for LDAP proxy
apiVersion: apps/v1
kind: Deployment
metadata:
  name: gsuite-ldap-proxy
spec:
  replicas: 3
  selector:
    matchLabels:
      app: ldap-proxy
  template:
    spec:
      containers:
      - name: proxy
        image: custom-gsuite-connector:1.2.0
        ports:
        - containerPort: 389
        env:
        - name: GSERVICE_ACCOUNT
          valueFrom:
            secretKeyRef:
              name: gsuite-secrets
              key: service-account.json

Remember to implement proper monitoring for the sync processes and establish clear failover procedures when Google's APIs experience downtime.