After editing the TCP wrapper configuration to grant specific hosts access to a service, when do these changes become effective?

Question

Options

• AThe new configuration becomes effective after restarting the respective service.
• BThe new configuration becomes effective at the next system reboot.
• CThe new configuration becomes effective when the last established connection to the service is
• DThe new configuration becomes effective after restarting the tcpd service.
• EThe new configuration becomes effective immediately for all new connections.

• A
  3% (1)
• C
  6% (2)
• D
  10% (3)
• E
  81% (25)

Explanation

TCP wrappers (/etc/hosts.allow and /etc/hosts.deny) are read by tcpd or the libwrap library on every new incoming connection, so edits take effect immediately without any restart - making E correct. Options A and D are wrong because TCP wrappers have no running daemon of their own to restart, and the service being wrapped (e.g., SSH) doesn't need restarting either. Option B is wrong because a reboot is never required for flat file configuration changes of this type. Option C is a plausible-sounding distractor, but connection state is irrelevant - the wrapper checks the files fresh each time a new connection arrives, regardless of existing ones.

Memory tip: Think of TCP wrapper config files like a bouncer's guest list - the bouncer checks the list for every new person who walks up, so updating the list works instantly for the next arrival.

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