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CompTIA XK0-005 Exam - Topic 3 Question 57 Discussion
Topic #: 3
Users report that they are unable to reach the company website https://www.comptia.org. A systems administrator confirms the issue with the following command:
# curl https://www.comptia.org
curl: (7) Failed to connect to www.comptia.org port 443: No route to host
The administrator logs in to the company's web server to check its configuration and sees the following output:
root@comptia.org:-># firewall-cmd --list-all
public (active)
target: default
icmp-block-inversion: no
interfaces: dummy0 eth0
sources:
services: cockpit dhcpv6-client http ssh
ports: 3001/tcp
protocols:
forward: no
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:
rule family="ipv4" source address="61.177.173.6" port port="ssh" protocol="tcp" reject type="icmp-port-unreachable"
rule family="ipv4" source address="185.143.45.164" port port="ssh" protocol="tcp" reject type="icmp-port-unreachable"
rule family="ipv4" source address="143.198.60.41" port port="ssh" protocol="tcp" reject type="icmp-port-unreachable"
root@comptia.org:-># ip route
default via 172.31.1.1 dev eth0 proto dhcp src 65.21.187.65 metric 100
10.0.6.0/24 dev dummy0 proto kernel scope link src 10.0.6.65 metric 550
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1
172.18.0.0/16 dev br-28ac2eaeeca1 proto kernel scope link src 172.18.0.1
172.19.0.0/16 dev br-fb3897555ca3 proto kernel scope link src 172.19.0.1 linkdown
172.31.1.1 dev eth0 proto dhcp scope link src 65.21.187.65 metric 100
192.168.224.0/20 dev br-e949ab177d79 proto kernel scope link src 192.168.224.1 linkdown
192.168.240.0/20 dev br-6adf72ac0ae3 proto kernel scope link src 192.168.240.1 linkdown
Which of the following is causing the issue?
The curl error 'No route to host' suggests that the server is unreachable on port 443 (HTTPS).
The firewall-cmd --list-all output shows the active firewall rules:
The firewall is only allowing the following services:services: cockpit dhcpv6-client http ssh
The firewall is only allowing the following services:services: cockpit dhcpv6-client http ssh
The firewall is only allowing the following services:services: cockpit dhcpv6-client http ssh
The firewall is only allowing the following services:services: cockpit dhcpv6-client http ssh
Port 443 (HTTPS) is missing from the allowed services list.
Port 3001/tcp is open, but port 443 is not listed, which means HTTPS traffic is being blocked.
The routing table (ip route output) appears correct, as the default route is properly set to 172.31.1.1 via eth0. This rules out option B.
Option A is incorrect because eth0 is active and configured (default via 172.31.1.1 dev eth0), meaning the network interface is not down.
Option D is misleading because the firewall rules are only rejecting SSH traffic from specific IP addresses, not HTTPS traffic.
Fixing the Issue:
To allow HTTPS traffic, the administrator should enable HTTPS in the firewall:
# firewall-cmd --add-service=https --permanent
# firewall-cmd --reload
This will allow HTTPS (port 443) through the firewall.
:
CompTIA Linux+ Official Documentation
firewalld Documentation - Red Hat
Linux Firewall Configuration - CompTIA Security+ Guide
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