Identifying Services Listening on TCP and UDP Ports

C.

The tool that an administrator should use to generate a list of services that are listening on TCP and/or UDP ports is netstat.

Netstat is a command-line utility tool that is used to display information about the network connections, open ports, and routing tables on a Linux system. It is installed by default on most Linux distributions, so you don't need to install it separately.

To list the services listening on TCP and/or UDP ports, you can use the following command:

Copy code
netstat -tulpn 

Here is what each option means:

• -t shows the TCP connections.
• -u shows the UDP connections.
• -l shows the listening sockets.
• -p shows the process that is using the socket.
• -n shows the numerical addresses instead of resolving them to hostnames.

The output of the command will display all the services that are listening on TCP and/or UDP ports, along with their corresponding Process IDs (PIDs) and the name of the program or service that is using them.

Option A, ethtool, is a command-line utility tool that is used to display and change the Ethernet device settings, such as speed, duplex, and link status. It is not used to display the services that are listening on TCP and/or UDP ports.

Option B, route, is a command-line utility tool that is used to display and manipulate the IP routing table. It is not used to display the services that are listening on TCP and/or UDP ports.

Option D, portmap, is a daemon process that provides an RPC port mapping service for the NFS (Network File System) and NIS (Network Information Service) services. It is not used to display the services that are listening on TCP and/or UDP ports.