TIME
=========

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        **What is TIME?**

        The TIME protocol is a simple network protocol used for retrieving the current time from a remote server. It allows clients to synchronize their clocks by receiving a timestamp from a server.

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        **Why is TIME useful?**

        * Provides an easy and lightweight way to synchronize system clocks.
        * Essential for logging and time-based functions in computer systems.
        * Often used in legacy systems or where precision time synchronization (like NTP) is not required.
        * Helps in the alignment of time across devices on a network.

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        **How it works?**

        * A client sends a request to a TIME server.
        * The server responds with the current time in a standardized format.
        * The client adjusts its system clock based on the received timestamp.
        * The protocol operates over TCP, using port 37 for communication.

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        **Where is TIME used?**

        * Often used in older systems or devices that need simple time synchronization.
        * Primarily found in legacy computing systems or embedded devices.
        * Used where high precision (like NTP) is not required, and basic time updates are sufficient.

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        **Which OSI layer does this protocol belong to?**

        * The TIME protocol operates at the Application Layer (Layer 7) of the OSI model.
        * It relies on the Transport Layer for communication, typically using TCP.

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        **Is TIME Windows specific?**

        * No, TIME is not Windows-specific.
        * It is supported on various operating systems, including UNIX, Linux, and even some embedded systems.

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        **Is TIME Linux specific?**

        * No, TIME is not Linux-specific.
        * It can be implemented on any operating system that supports TCP/IP and can use port 37 for communication.

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        **Which Transport Protocol is used by TIME?**

        * TIME typically uses TCP (Transmission Control Protocol) for communication.
        * It ensures reliable, ordered transmission of time data from the server to the client.

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        **Which Port is used by TIME?**

        * The TIME protocol operates over TCP port 37 for communication between the client and server.

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        **Is TIME using Client-server model?**

        * Yes, the TIME protocol follows the client-server model.
        * The client sends a request to the server, which then responds with the current time.

        

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        Topics in this section,

                * :ref:`Learnings in this section <TIME_step1>`

                * :ref:`Terminology <TIME_step2>`

                * :ref:`Version Info <TIME_step3>`

                * :ref:`TIME Version&RFC Details <TIME_step5>`

                * :ref:`TIME Basic Setup on Ubuntu using IPv4 <TIME_step19>`
                  
                * :ref:`TIME Basic Setup on Ubuntu using IPv6 <TIME_step20>`
                  
                * :ref:`TIME Protocol Packet Details <TIME_step6>`

                * :ref:`TIME Usecases <TIME_step7>`

                * :ref:`TIME Basic Features <TIME_step8>`
                    
                * :ref:`TIME Feature : Simplicity <TIME_step9>` 

                * :ref:`TIME Feature : Ligthweight Communication <TIME_step10>`

                * :ref:`TIME Feature : TCP and UDP Support <TIME_step11>`  

                * :ref:`TIME Feature : Fixed Epoch <TIME_step12>`  

                * :ref:`TIME Feature : Stateless Server <TIME_step13>`

                * :ref:`TIME Feature : Firewall Friendly <TIME_step14>`

                * :ref:`TIME Feature : Cross Platform Compatibility <TIME_step15>`   

                * :ref:`TIME Feature : No Authentication Required <TIME_step16>` 

                * :ref:`TIME Feature : Legacy System Support <TIME_step17>` 

                * :ref:`TIME Feature : Quick Time Retrieval <TIME_step18>`

                * :ref:`Reference links <TIME_step21>`


.. _TIME_step1:

.. tab-set::

    .. tab-item:: Learnings in this section

        * In this section, you are going to learn

.. _TIME_step2:

.. tab-set::

    .. tab-item:: Terminology
        
       * Terminology


.. _TIME_step3:

.. tab-set::

    .. tab-item:: Version Info
    
         * Version Info

        

.. _TIME_step5:

.. tab-set::

    .. tab-item:: TIME Version&RFC Details

        
         .. csv-table:: 
               :file: ./TIME/TIME_RFC_Details.csv
               :widths: 10,10,10,30
               :header-rows: 1

.. _TIME_step19:

.. tab-set::

  .. tab-item:: TIME Basic Setup on Ubuntu using IPv4

     **TIME protocol over TCP using IPv4 on interface enp0s8**

      * Step-1: Assign IPv4 Addresses for two VM's.

        .. code-block:: shell

           test:~$sudo ip addr add 192.168.200.1/24 dev enp0s8
           test:~$sudo ip link set enp0s8 up
           test:~$sudo ip addr add 192.168.200.2/24 dev enp0s8
           test:~$sudo ip link set enp0s8 up
     
      * Step-2: Create TIME Service Configs.

        .. code-block:: shell

           test:~$sudo nano /etc/xinetd.d/time-tcp

      * Step-3: Enable and Start xinetd.

        .. code-block:: shell

           test:~$sudo systemctl enable xinetd
           test:~$sudo systemctl restart xinetd

      * Step-4: Verify TIME service is listening.

        .. code-block:: shell

           test:~$sudo netstat -tulnp | grep ":37"


      * Step-5: Test from Another VM.

        .. code-block:: shell

           test:~$rdate -p 192.168.200.1
           You should see the current time printed

      * Step-6:  Wireshark Capture.

         :download:Download wireshark capture <TIME/time_ipv4_tcp.pcapng>




.. _TIME_step20:

.. tab-set::

   .. tab-item:: TIME Basic Setup on Ubuntu using IPv6
   
      **TIME protocol over TCP using IPv6 on interface enp0s8**

      * Step-1: Assign IPv6 Addresses for two VM's.

        .. code-block:: shell

           test:~$sudo ip addr add 2001:db8:abcd:1/64 dev enp0s8
           test:~$sudo ip link set enp0s8 up
           test:~$sudo ip addr add 2001:db8:abcd:2/64 dev enp0s8
           test:~$sudo ip link set enp0s8 up

      * Step-2: Install Required Packages.

        .. code-block:: shell

           test:~$sudo apt update
           test:~$sudo apt install -y xinetd rdate net-tools

      * Step-3: Create TIME Service Configs (IPv6).

        .. code-block:: shell

           test:~$sudo nano /etc/xinetd.d/time-stream


      * Step-4: Enable and Start xinetd.

        .. code-block:: shell

           test:~$sudo systemctl enable xinetd
           test:~$sudo systemctl restart xinetd


      * Step-5: Verify TIME service is listening on IPv6.

        .. code-block:: shell

           test:~$sudo ss -tln6 | grep :37    # TCP

     * Step-6: Test from Another IPv6 VM.

        .. code-block:: shell

           test:~$rdate -6 -p 2001:db8:abcd::1

      * Step-6:  Wireshark Capture.
         :download:Download wireshark capture <TIME/time_ipv6_tcp.pcapng>


.. _TIME_step6:

.. tab-set::

    .. tab-item:: TIME Protocol Packet Details
       
         **Client Request Packet**

         .. csv-table:: 
                :file: ./TIME/TIME_Protocol_Packet_1.csv
                :widths: 10,20,30,10
                :header-rows: 1

         **Server Response Packet**

         .. csv-table:: 
                :file: ./TIME/TIME_Protocol_Packet_2.csv
                :widths: 10,20,30,10
                :header-rows: 1


.. _TIME_step7:

.. tab-set::

    .. tab-item:: TIME Usecases
        
        
         .. csv-table:: 
               :file: ./TIME/TIME_Usecases.csv
               :widths: 10,20,30
               :header-rows: 1

.. _TIME_step8:

.. tab-set::

    .. tab-item:: TIME Basic Features
    
         
         .. csv-table:: 
                  :file: ./TIME/TIME_Features.csv
                  :widths: 10,10,30
                  :header-rows: 1

.. _TIME_step9:

.. tab-set::

    .. tab-item:: TIME Feature : Simplicity

          **Simplicity - Testcases**

          .. csv-table:: 
                 :file: ./TIME/TIME_Feature_1_Simplicity_Testcase.csv
                 :widths: 10,10,30,20
                 :header-rows: 1


   
.. _TIME_step10:

.. tab-set::

    .. tab-item:: TIME Feature : Ligthweight Communication

         **Ligthweight Communication - Testcases**

         .. csv-table:: 
                :file: ./TIME/TIME_Feature_2_Ligthweight_Communication_Testcase.csv
                :widths: 10,10,30,20
                :header-rows: 1


.. _TIME_step11:

.. tab-set::

    .. tab-item:: TIME Feature : TCP and UDP Support

        **TCP and UDP Support - Testcases**

        .. csv-table:: 
                 :file: ./TIME/TIME_Feature_3_TCP_and_UDP_Support_Testcase.csv
                 :widths: 10,10,30,20
                 :header-rows: 1


.. _TIME_step12:

.. tab-set::

    .. tab-item:: TIME Feature : Fixed Epoch

          **Fixed Epoch - Testcases**

          .. csv-table:: 
                :file: ./TIME/TIME_Feature_4_Fixed_Epoch_Testcase.csv
                :widths: 10,10,30,20
                :header-rows: 1



.. _TIME_step13:

.. tab-set::

    .. tab-item:: TIME Feature : Stateless Server 

          **Stateless Server - Testcases**

         .. csv-table:: 
                 :file: ./TIME/TIME_Feature_5_Stateless_Server_Testcase.csv
                 :widths: 10,10,30,20
                 :header-rows: 1


 
.. _TIME_step14:

.. tab-set::

    .. tab-item:: TIME Feature : Firewall Friendly

         **Firewall Friendly - Testcases**

         .. csv-table:: 
                  :file: ./TIME/TIME_Feature_6_Firewall_Friendly_Testcase.csv
                  :widths: 10,10,30,20
                  :header-rows: 1


.. _TIME_step15:

.. tab-set::

    .. tab-item:: TIME Feature : Cross Platform Compatibility
   
          **Cross Platform Compatibility  - Testcases**

          .. csv-table:: 
                 :file: ./TIME/TIME_Feature_7_Cross_Platform_Compatibility_Testcase.csv
                 :widths: 10,10,30,20
                 :header-rows: 1


.. _TIME_step16:

.. tab-set::

    .. tab-item:: TIME Feature : No Authentication Required

         **No Authentication Required - Testcases**

         .. csv-table:: 
                 :file: ./TIME/TIME_Feature_8_NO_Authentication_Required_Testcase.csv
                 :widths: 10,10,30,20
                 :header-rows: 1


.. _TIME_step17:

.. tab-set::

    .. tab-item:: TIME Feature : Legacy System Support

        **Legacy System Support - Testcases**

        .. csv-table::
                :file: ./TIME/TIME_Feature_9_Legacy_System_Support_Testcase.csv
                :widths: 10,10,30,20
                :header-rows: 1

.. _TIME_step18:

.. tab-set::

    .. tab-item:: TIME Feature : Quick Time Retrieval

        **Quick Time Retrieval - Testcases**

        .. csv-table::
                :file: ./TIME/TIME_Feature_10_Quick_Time_Retrieval_Testcase.csv
                :widths: 10,10,30,20
                :header-rows: 1


.. _TIME_step21:

.. tab-set::

    .. tab-item:: Reference links
     
       * Reference links