0201-listening-ports-del - Host Port Closed¶

Rule ID¶

• 0201-listening-ports-del

Category¶

• system

Severity¶

• warn

Compatible Versions¶

• Linux

Description¶

• A port is an outlet for communication between a device and the outside world. Ports can be divided into virtual ports and physical ports. Virtual ports refer to ports inside a computer or within switches and routers and are not visible, for example, port 80, port 21, and port 23 on a computer. Physical ports, also called interfaces, are visible ports such as the RJ45 Ethernet port on the back of a computer, or the RJ45 ports on switches, routers, and hubs. The RJ11 connector used by telephones is also a type of physical port.

Scan Frequency¶

• 1 */5 * * *

Rationale¶

• If a host port is closed, the corresponding service may become unavailable.

Risk Items¶

• Service unavailability

Audit Method¶

• Execute the following command to list the listening ports on Linux:

  netstat -nltp
  

  Verify that the ports listed are known ports.

Remediation¶

• None

Impact¶

• None

Default Value¶

• None

References¶

• None

CIS Controls¶

• None