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Process

🧱 1. Set Up the LDAP Server

What you need:

  • A running OpenLDAP server
  • A web interface (PLA - phpLDAPadmin) to manually manage entries

Actions:

  • Run an OpenLDAP Docker container (e.g., osixia/openldap)
  • Run a PLA Docker container and link it to the LDAP container
  • Access PLA via browser to visually build your directory

Directory Structure (DIT):

Build a basic Directory Information Tree like this: 

dc=example,dc=com
└── ou=Friends
    ├── uid=jdoe
    │   ├── cn: John Doe
    │   ├── telephoneNumber: 123-456-7890
    └── uid=asmith
        ├── cn: Alice Smith
        ├── telephoneNumber: 987-654-3210

🔐 2. Bind to the Server

What it means:

“Binding” is like logging in. You authenticate to LDAP so you can read or modify the directory.

Steps:

  • Connect to port 389 on the server using a TCP socket
  • Craft a BindRequest using ASN.1/BER encoding manually
    • Contains version (3), bind DN (e.g. cn=admin,dc=example,dc=com), and password
  • Send the BindRequest over the socket
  • Wait for and parse the BindResponse to ensure login success

🔍 3. Query via SearchRequest

Objective:

Search for a friend’s record based on their UID (e.g., uid=jdoe) and retrieve their telephoneNumber.

Steps:

  • Use the same socket connection from the bind step
  • Construct a SearchRequest packet:
    • Base DN: ou=Friends,dc=example,dc=com
    • Scope: Subtree
    • Filter: Equality filter (uid=jdoe)
    • Attributes: telephoneNumber
  • Encode all of that as a BER-encoded byte stream
  • Send it through the socket

📩 4. Read and Parse the Response

What you'll get back:

An LDAPMessage that wraps one or more SearchResultEntry objects.

Each entry will include: - Distinguished Name (DN) - One or more attributes (e.g., telephoneNumber)

Steps:

  • Read the raw bytes returned from the socket
  • Parse them manually (byte or string-level operations)
  • Look for the attribute name telephoneNumber and extract the value next to it

🧪 5. Display the Result

  • Once the number is extracted, display it in the terminal
  • If no result, show a “Not Found” message

🔁 6. Repeat

You should be able to run the program multiple times, input different UIDs, and get different results based on who exists in the LDAP directory.

✅ Summary of Steps

Step Action
1 Launch OpenLDAP + phpLDAPadmin via Docker
2 Use PLA to create users under ou=Friends
3 Open socket to LDAP server on port 389
4 Send manual BindRequest with DN + password
5 Build and send a SearchRequest for uid=<name>
6 Read the SearchResponse, parse telephoneNumber
7 Print result to user