LX0-104 · Question #221
Which of the following are builtin chains for the iptables nat table? (Select THREE correct answers)
The correct answer is A. OUTPUT D. POSTROUTING E. PREROUTING. The iptables nat table uses specific built-in chains to handle Network Address Translation for packets at various points in their traversal.
Question
Options
- AOUTPUT
- BINPUT
- CPROCESSING
- DPOSTROUTING
- EPREROUTING
How the community answered
(42 responses)- A90% (38)
- B5% (2)
- C5% (2)
Why each option
The iptables `nat` table uses specific built-in chains to handle Network Address Translation for packets at various points in their traversal.
The `OUTPUT` chain in the `nat` table is used for altering packets originating from the local system before they are routed, typically for Source NAT (SNAT).
The `INPUT` chain is a built-in chain in the `filter` table for packets destined for the local host, but it is not a built-in chain in the `nat` table.
`PROCESSING` is not a standard built-in chain in any iptables table.
The `POSTROUTING` chain in the `nat` table is used for altering packets as they are about to leave the system, commonly for Source NAT (SNAT).
The `PREROUTING` chain in the `nat` table is used for altering incoming packets as soon as they arrive but before routing decisions are made, commonly for Destination NAT (DNAT).
Concept tested: Iptables nat table built-in chains
Source: https://man7.org/linux/man-pages/man8/iptables.8.html
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