Linux+ V7 iptables Firewall Rules Quiz

1. What is the purpose of the OUTPUT chain in iptables?

Filter packets generated by the local system

Filter incoming packets

Route packets between interfaces

Log rejected packets

2. Which iptables command sets the default policy for a chain to DROP?

Iptables -P INPUT DROP

Iptables -F INPUT DROP

Iptables -D INPUT DROP

Iptables -I INPUT DROP

3. What is the purpose of the -i flag in an iptables rule?

Specify the input network interface

Specify the insertion position

Specify the IP address

Specify the protocol

4. To block ICMP ping requests, which iptables rule would you use?

Iptables -A INPUT -p icmp --icmp-type echo-request -j DROP

Iptables -A INPUT -p icmp -j DROP

Iptables -A OUTPUT -p icmp -j DROP

Iptables -A FORWARD -p icmp --icmp-type echo-reply -j DROP

5. Which command inserts a rule at a specific position in an iptables chain?

Iptables -I INPUT 5 -p tcp --dport 22 -j ACCEPT

Iptables -A INPUT 5 -p tcp --dport 22 -j ACCEPT

Iptables -R INPUT 5 -p tcp --dport 22 -j ACCEPT

Iptables -P INPUT 5 -p tcp --dport 22 -j ACCEPT

6. What does the -d flag specify in an iptables rule?

Destination IP address

Source IP address

Destination port

Device interface

7. Which file stores iptables rules persistently across reboots on most systems?

/etc/iptables/rules.v4

/etc/firewall.conf

/proc/iptables

/sys/net/iptables

8. What does REJECT do differently than DROP in iptables?

REJECT sends an error message back to the sender

REJECT logs the packet

REJECT blocks the entire connection

REJECT only works for UDP

9. To deny all traffic from a specific IP address, which rule would you use?

Iptables -A INPUT -s 192.168.1.10 -j DROP

Iptables -A OUTPUT -s 192.168.1.10 -j DROP

Iptables -A FORWARD -d 192.168.1.10 -j DROP

Iptables -A INPUT -d 192.168.1.10 -j REJECT

10. Which iptables option allows you to specify a range of ports?

--dport 80:443

--dport 80,443

--dport 80-443

--port-range 80:443

11. Which iptables chain is responsible for filtering incoming packets destined for the local system?

INPUT

OUTPUT

FORWARD

PREROUTING

12. Which iptables command removes all rules from a specific chain?

Iptables -F INPUT

Iptables -D INPUT

Iptables -P INPUT DROP

Iptables -Z INPUT

13. What does the -p flag specify in an iptables rule?

Protocol (tcp, udp, icmp)

Port number

Policy action

Packet priority

14. Which command lists all current iptables rules with line numbers?

Iptables -L -n --line-numbers

Iptables -S

Iptables -P

Iptables -F

15. What does the -m state --state ESTABLISHED,RELATED option allow in iptables?

Return traffic from established connections

Block all incoming connections

Log all packets

Enable IP forwarding

16. To allow SSH access on port 22 from any source, which iptables rule would you use?

Iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Iptables -A OUTPUT -p tcp --dport 22 -j ACCEPT

Iptables -A FORWARD -p tcp --dport 22 -j ACCEPT

Iptables -A INPUT -p udp --dport 22 -j ACCEPT

17. Which iptables target is used to silently discard packets without sending a response?

DROP

REJECT

ACCEPT

LOG

18. What does the -s flag represent in an iptables rule?