Session Layer Protocols In Osi Reference Model

The Session Layer (Layer 5) of the OSI (Open Systems Interconnection) model is responsible for managing and controlling the sessions between applications. It establishes, maintains, and terminates connections between applications on different devices. It also provides synchronization and recovery mechanisms to ensure reliable communication.

Unlike the Application Layer, which interacts directly with user applications, the Session Layer deals with the management of the dialogue between applications.

Protocols Operating at the Session Layer

1. NetBIOS (Network Basic Input/Output System)

   • Purpose: Provides services for applications to communicate over a network, including name resolution and session management.

   • Usage: Often used in Windows networks for file sharing and printer access.

   • Port: 137 (name service), 138 (datagram service), 139 (session service).

2. RPC (Remote Procedure Call)

   • Purpose: Allows a program to execute code on a remote server as if it were a local procedure call.

   • Usage: Used for client-server communication where remote functions are called by a client application.

3. SMB (Server Message Block)

   • Purpose: Provides file sharing, printer sharing, and other network services.

   • Usage: Often used in Windows networks for accessing shared files and printers.

   • Port: 445 (for direct hosting), 139 (NetBIOS session service).

4. PPTP (Point-to-Point Tunneling Protocol)

   • Purpose: Used for creating virtual private network (VPN) connections over a public network.

   • Usage: Provides secure remote access to a private network.

   • Port: 1723.

5. L2TP (Layer 2 Tunneling Protocol)

   • Purpose: Used in conjunction with VPNs to create secure connections over a public network.

   • Usage: Provides tunneling and session management.

   • Port: 1701.