LX0-104 · Question #225
What does the following iptables rule accomplish: iptables A INPUT s 208.77.188.166 d 10.142.232.1 p tcp dport 22 j ACCEPT
The correct answer is C. Forwards all requests from the host 208.77.188.166 on port 22 the internal host 10.142.232.1. This iptables rule, when implemented on a gateway or firewall, allows SSH traffic from a specific external host to be directed to a particular internal host.
Question
Options
- AAccepts traffic on port 22 only from the hosts 208.77.188.166 and 10.142.232.1.
- BForwards all requests from the host 10.142.232.1 on port 22 the internal host 208.77.188.166
- CForwards all requests from the host 208.77.188.166 on port 22 the internal host 10.142.232.1
- DDrops traffic on port 22 only from the hosts 208.77.188.166 and 10.142.232.1.
How the community answered
(22 responses)- A9% (2)
- B5% (1)
- C86% (19)
Why each option
This iptables rule, when implemented on a gateway or firewall, allows SSH traffic from a specific external host to be directed to a particular internal host.
The rule specifies traffic from `208.77.188.166` to `10.142.232.1`, not from both hosts.
This option reverses the source and destination IP addresses specified in the rule.
Although the `INPUT` chain is primarily for traffic destined for the firewall itself, in a network context where the firewall performs NAT (Network Address Translation), this rule is intended to allow SSH (port 22, TCP) connections originating from the external host `208.77.188.166` to be forwarded to the internal host `10.142.232.1`.
The `-j ACCEPT` target explicitly means to allow the traffic, not to drop it.
Concept tested: Iptables rule interpretation for NAT/forwarding
Source: https://man7.org/linux/man-pages/man8/iptables.8.html
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