Linux Firewall and Network Security 2

Question 1

Which iptables table is responsible for altering packet headers such as TTL and TOS fields?

Accepted Answer

mangle

Answer

The mangle table is used to modify packet headers, including TTL, TOS, and MARK fields.

Question 2

What nftables command lists all current rules across all tables and chains?

Accepted Answer

nft list ruleset

Answer

'nft list ruleset' outputs the complete nftables configuration including all tables, chains, and rules.

Question 3

Which firewalld zone is most restrictive and drops all incoming connections without any notification?

Accepted Answer

drop

Answer

The 'drop' zone silently discards all incoming packets, while 'block' sends an ICMP rejection message.

Question 4

In iptables, what does the '-j RETURN' target do when used inside a user-defined chain?

Accepted Answer

Returns to the calling chain and continues matching

Answer

RETURN exits the current user-defined chain and resumes rule matching in the parent chain that invoked it.

Question 5

Which command adds a permanent firewalld service rule to the public zone without applying it immediately?

Accepted Answer

firewall-cmd --zone=public --add-service=http --permanent

Answer

The --permanent flag writes the rule to the persistent configuration but requires --reload to take effect at runtime.

Linux Practice Test