After adding ALL : ALL to hosts.deny, a network daemon still accepts connections.
Check TCP Wrappers applicability separately from the firewall.
What should be checked first?
hosts.allow and hosts.deny apply only to daemons using libwrap or running through tcpd. Unsupported services need firewall or service-specific controls.
Detailed explanation
Incorrect. Privileged-port status does not determine libwrap support.
Incorrect. Privileged-port status does not determine libwrap support.
Correct. Only a libwrap-aware or tcpd-wrapped daemon consults these files.
Correct. Only a libwrap-aware or tcpd-wrapped daemon consults these files.
Incorrect. SUID is unrelated to TCP Wrappers rule lookup.
Incorrect. SUID is unrelated to TCP Wrappers rule lookup.
Incorrect. The address family alone does not determine libwrap support.
Incorrect. The address family alone does not determine libwrap support.
Try it yourself
An example you can run in a temporary verification environment.
printf '%s
' 'hosts.allow/deny effective only when daemon invokes TCP Wrappers access checks'Expected result
hosts.allow/deny effective only when daemon invokes TCP Wrappers access checksKey points
- Check daemon libwrap support
- Not every service is covered
- Separate from the firewall layer
Notes
- Environment: TCP Wrappers適用条件の表示のみ
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.