List All Open Ports on Linux

List All Open Ports on Linux is a Bash script designed to audit every port a Linux server listens on, helping users identify services that may be unintentionally exposed to external networks. The script provides a comprehensive overview of open TCP and UDP ports, showing which processes are associated with each port and clarifying whether a port is bound to all interfaces or restricted to localhost. This aids in detecting misconfigured services, forgotten debug ports, or unexpected packages that may have opened network access without the user's knowledge.

The script operates by first checking for the availability of the 'ss' command, which has replaced 'netstat' as the default tool on modern Linux distributions for listing socket information. For process-to-port mapping, it leverages 'lsof' to provide a process-centric view of listening sockets. Running the script with root privileges (using sudo) enables it to display complete process details for all ports; when run without root, ports owned by other users may not display their associated process names. 1 or ::1), making it straightforward to assess network exposure.

Additional usage examples are provided, such as filtering for a specific port, identifying only externally reachable ports, and checking port status on remote hosts. The script can be scheduled to run at regular intervals, with output differences emailed to an administrator, enabling ongoing monitoring for newly opened ports that might result from configuration changes or software updates.

This tool is intended for Linux users, particularly system administrators and security-conscious operators, who need to regularly audit network exposure on their servers. It is delivered as a Bash script to be executed from the command line.