The security status of my operating system

Use the command line netstat -np tcp in the shell

The entry TCP 127.0.0.1:56663 127.0.0.1:64867 ESTABLISHED shows an active, secure connection occurring on your local computer. Here is a breakdown of what each part means.

TCP: Transmission Control Protocol. This is a standard internet protocol that provides reliable, ordered, and error-checked delivery of data. It establishes a connection before data transfer begins.

127.0.0.1: This is the loopback IP address, also known as localhost. It is a special-use address that allows a computer to refer to itself. Any traffic sent to this address is rerouted internally and never leaves the device.

127.0.0.1:56663: This indicates that one application on your local machine is communicating with another application on the same machine.

• 127.0.0.1: The source IP address.
• 56663: This is an ephemeral port number, meaning it was temporarily assigned by the operating system for this specific connection. The fact that it’s in the high range (above 32768) indicates it is likely a client-side port.

127.0.0.1:64867: This specifies the destination address and port for the same local connection.

• 127.0.0.1: The destination IP address, which is also your local machine.
• 64867: This is another ephemeral port, temporarily assigned to another application or service on your computer.

What I found based upon what my operating system reported.

ESTABLISHED: This is the state of the TCP connection. It indicates that the three-way handshake was successfully completed, and data can now be sent in both directions between the two applications.

Summary

The entry signifies that a communication channel has been created between two different processes running on your computer. One process is using port 56663, and the other is using 64867. They are talking to each other securely and reliably using the TCP protocol, but the data never leaves your computer. This is a normal occurrence for many applications that use internal components or services. (Team, 2024)

The entry TCP 192.168.40.69:50072 192.168.40.1:53 TIME_WAIT indicates a normal, temporary state of a closed TCP connection. It is not an error but a standard part of the TCP shutdown process. This specific entry shows that a device at a private IP address (192.168.40.69) was acting as a client, initiating a DNS query to a server at another private IP address (192.168.40.1).

Here is a breakdown of what the entry means:

• TCP: The connection is using the Transmission Control Protocol.
• 192.168.40.69:50072: This is the client side of the connection.

• • 192.168.40.69: The private IP address of the client device (e.g., a computer, phone).
  • 50072: The ephemeral (short-lived) port number assigned by the client’s operating system for this specific session.
• 192.168.40.1:53: This is the server side of the connection.
  • 192.168.40.1: The private IP address of the server, which is likely your network’s router or a dedicated DNS server.
  • 53: The well-known port for the Domain Name System (DNS) service. This indicates the purpose of the traffic was a DNS request.
• TIME_WAIT: The state of the connection.
  • Function: This state is for a socket that has been locally closed (by the client in this case). The system keeps the connection information active for a duration known as 2MSL (twice the Maximum Segment Lifetime), typically around 4 minutes.
  • Purpose: This waiting period prevents delayed or retransmitted packets from a previous connection from being mixed up with a new one if the same port combination is reused. It also ensures that the final acknowledgement of the connection termination is successfully received by the other side.

What I found based upon what my operating system reported.

Is this a problem?

In most cases, seeing a connection in TIME_WAIT is completely normal and expected behavior after a network application has finished its work and properly closed its connection. A single entry is not a cause for concern.

Potential issue: Too many TIME_WAIT connections

If you see an extremely large number of TIME_WAIT connections, it could indicate a resource exhaustion issue on the client device. This can occur in high-traffic scenarios (e.g., a busy web server) where a large number of connections are rapidly opened and closed, potentially consuming all available ephemeral ports. For a typical home or small business network, a high number of TIME_WAIT states is rare. (Team, 2024)

The entry TCP 192.168.40.69:59780 57.144.181.32:443 CLOSE_WAIT indicates a half-closed connection, likely from a server, where the remote client has initiated a shutdown, but the local application has not yet closed its end of the connection.

Breaking down the entry

• TCP: This specifies the Transmission Control Protocol, a connection-oriented protocol used for reliable communication.
• 192.168.40.69: This is the local machine’s IP address on a private network.
• 59780: This is the dynamic or ephemeral source port on your local machine used for this specific connection.
• 57.144.181.32: This is the IP address of the remote machine (the client).
• 443: This is the standard port for HTTPS traffic on the remote machine.
• CLOSE_WAIT: This is the state of the TCP connection on your local machine.

The CLOSE_WAIT state explained

A TCP connection transitions through several states during its lifecycle, and CLOSE_WAIT signifies a specific phase in the closing sequence. The sequence of events is as follows:

1. The client (57.144.181.32) sends a FIN (Finish) packet to signal it is done sending data and wants to close its side of the connection.
2. Your server (192.168.40.69) receives this FIN and acknowledges it. The connection on your server’s side then enters the CLOSE_WAIT state.
3. In this state, the server is expected to stop sending any remaining data and then close its end of the connection.
4. The problem: If a connection remains in the CLOSE_WAIT state for a long time, it typically means the local application has failed to close the socket. This can lead to issues like resource exhaustion if too many connections accumulate in this state.

What I found based upon what my operating system reported.

Potential causes of persistent CLOSE_WAIT connections

• Application bug: A flaw in the application code prevents it from properly closing the socket after the remote end has disconnected.
• Slow application processing: The application is too busy with other tasks and is delayed in processing the connection closure request.
• Stuck or hung process: The application process that owns the socket has crashed or become unresponsive, leaving the socket open.
• Client abruptly terminated: The client machine may have lost power or crashed without sending a proper TCP shutdown message. (Team, 2024)

These may expose security issues.

I can reduce workstation TCP/IP vulnerabilities by leveraging SANS controls such as;

2. Inventory and Control of Software Assets-This CIS critical security control, requires the organization to inventory (track, analyze, correct, and delete) all software that is installed on the network. This is to ensure that unauthorized software is not installed or executed.

3. Continuous Vulnerability Management-This requires the continuous identification of weaknesses and security vulnerabilities and their effective remediation. The focus in CIS critical security control 3 is on information, specifically the gaining of current information and the active response to new information about cybersecurity vulnerabilities.

4. Controlled Use of Administrative Privileges- This CIS critical security control requires that the organization tracks and manages (analyze, correct, remediate, or delete) who has administrative privileges (admin privileges).

5. Secure Configuration for Hardware and Software on Mobile Devices, Laptops, Workstations, and Servers-Implement this  through stringent hardware and software change management and configuration protocols .Out of the box hardware and software are usually configured to make installation and initial operation easy for the user. In practice, this means that security settings are at their lowest and bad actors and attackers exploit these well-known vulnerabilities.

References

RSI Security. (2024, November 18). What are the 20 CIS critical security controls? https://blog.rsisecurity.com/what-are-the-20-cis-critical-security-controls/

Team, H. (2024, August 16). Loopback address – what is IT & how does it work?: Hostwinds. Hostwinds Blog. https://www.hostwinds.com/blog/loopback-address