RHEL9-CIS/tasks/section_3/cis_3.4.3.x.yml

---

- name: "3.4.3.1 | L1 | PATCH | Ensure iptables are flushed with nftables"
  command: ip6tables -F
  when:
      - rhel9cis_rule_3_4_3_1
      - rhel9cis_firewall != "iptables"
      - rhel9cis_ipv6_required
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.1

- name: "3.4.3.2 | L1 | AUDIT | Ensure an nftables table exists"
  block:
      - name: "3.4.3.2 | L1 | AUDIT | Ensure a table exists | Check for tables"
        command: nft list tables
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_2_nft_tables

      - name: "3.4.3.2 | L1 | AUDIT | Ensure an nftables table exists | Show existing tables"
        debug:
            msg:
                - "Below are the current nft tables, please review"
                - "{{ rhel9cis_3_4_3_2_nft_tables.stdout_lines }}"
        when: rhel9cis_3_4_3_2_nft_tables.stdout | length > 0

      - name: "3.4.3.2 | L1 | AUDIT | Ensure an nftables table exists | Alert on no tables"
        debug:
            msg:
                - "Warning! You currently have no nft tables, please review your setup"
                - 'Use the command "nft create table inet <table name>" to create a new table'
        when:
            - rhel9cis_3_4_3_2_nft_tables.stdout | length == 0
            - not rhel9cis_nft_tables_autonewtable

      - name: "3.4.3.2 | L1 | PATCH | Ensure a table exists | Create table if needed"
        command: nft create table inet "{{ rhel9cis_nft_tables_tablename }}"
        failed_when: no
        when: rhel9cis_nft_tables_autonewtable
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_2
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.2

- name: "3.4.3.3 | L1 | PATCH | Ensure nftables base chains exist"
  block:
      - name: "3.4.3.3 | L1 | Ensure nftables base chains exist | Get current chains for INPUT"
        shell: nft list ruleset | grep 'hook input'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_3_input_chains

      - name: "3.4.3.3 | L1 | AUDIT | Ensure nftables base chains exist | Get current chains for FORWARD"
        shell: nft list ruleset | grep 'hook forward'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_3_forward_chains

      - name: "3.4.3.3 | L1 | AUDIT | Ensure nftables base chains exist | Get current chains for OUTPUT"
        shell: nft list ruleset | grep 'hook output'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_3_output_chains

      - name: "3.4.3.3 | L1 | AUDIT | Ensure nftables base chains exist | Display chains for review"
        debug:
            msg:
                - "Below are the current INPUT chains"
                - "{{ rhel9cis_3_4_3_3_input_chains.stdout_lines }}"
                - "Below are the current FORWARD chains"
                - "{{ rhel9cis_3_4_3_3_forward_chains.stdout_lines }}"
                - "Below are teh current OUTPUT chains"
                - "{{ rhel9cis_3_4_3_3_output_chains.stdout_lines }}"
        when: not rhel9cis_nft_tables_autochaincreate

      - name: "3.4.3.3 | L1 | PATCH | Ensure nftables base chains exist | Create chains if needed"
        shell: "{{ item }}"
        args:
            warn: no
        failed_when: no
        with_items:
            - nft create chain inet "{{ rhel9cis_nft_tables_tablename }}" input { type filter hook input priority 0 \; }
            - nft create chain inet "{{ rhel9cis_nft_tables_tablename }}" forward { type filter hook forward priority 0 \; }
            - nft create chain inet "{{ rhel9cis_nft_tables_tablename }}" output { type filter hook output priority 0 \; }
        when: rhel9cis_nft_tables_autochaincreate
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_3
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.3

- name: "3.4.3.4 | L1 | PATCH | Ensure nftables loopback traffic is configured"
  block:
      - name: "3.4.3.4 | L1 | AUDIT | Ensure nftables loopback traffic is configured | Gather iif lo accept existence"
        shell: nft list ruleset | awk '/hook input/,/}/' | grep 'iif "lo" accept'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_4_iiflo

      - name: "3.4.3.4 | L1 | AUDIT | Ensure nftables loopback traffic is configured | Gather ip saddr existence"
        shell: nft list ruleset | awk '/hook input/,/}/' | grep 'ip saddr'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_4_ipsaddr

      - name: "3.4.3.4 | L1 | AUDIT | Ensure nftables loopback traffic is configured | Gather ip6 saddr existence"
        shell: nft list ruleset | awk '/hook input/,/}/' | grep 'ip6 saddr'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_4_ip6saddr

      - name: "3.4.3.4 | L1 | PATCH | Ensure nftables loopback traffic is configured | Set iif lo accept rule"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input iif lo accept
        when: '"iif \"lo\" accept" not in rhel9cis_3_4_3_4_iiflo.stdout'

      - name: "3.4.3.4 | L1 | PATCH | Ensure nftables loopback traffic is configured | Set ip sddr rule"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input ip saddr 127.0.0.0/8 counter drop
        when: '"ip saddr 127.0.0.0/8 counter packets 0 bytes 0 drop" not in rhel9cis_3_4_3_4_ipsaddr.stdout'

      - name: "3.4.3.4 | L1 | PATCH | Ensure nftables loopback traffic is configured | Set ip6 saddr rule"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input ip6 saddr ::1 counter drop
        when: '"ip6 saddr ::1 counter packets 0 bytes 0 drop" not in rhel9cis_3_4_3_4_ip6saddr.stdout'
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_4
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.4

- name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured"
  block:
      - name: "3.4.3.5 | L1 | AUDIT | Ensure nftables outbound and established connections are configured | Gather incoming connection rules"
        shell: nft list ruleset | awk '/hook input/,/}/' | grep -E 'ip protocol (tcp|udp|icmp) ct state'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_5_inconnectionrule

      - name: "3.4.3.5 | L1 | AUDIT | Ensure nftables outbound and established connections are configured | Gather outbound connection rules"
        shell: nft list ruleset | awk '/hook output/,/}/' | grep -E 'ip protocol (tcp|udp|icmp) ct state'
        changed_when: false
        failed_when: false
        register: rhel9cis_3_4_3_5_outconnectionrule

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add input tcp established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input ip protocol tcp ct state established accept
        when: '"ip protocol tcp ct state established accept" not in rhel9cis_3_4_3_5_inconnectionrule.stdout'

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add input udp established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input ip protocol udp ct state established accept
        when: '"ip protocol udp ct state established accept" not in rhel9cis_3_4_3_5_inconnectionrule.stdout'

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add input icmp established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input ip protocol icmp ct state established accept
        when: '"ip protocol icmp ct state established accept" not in rhel9cis_3_4_3_5_inconnectionrule.stdout'

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add output tcp new, related, established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" output ip protocol tcp ct state new,related,established accept
        when: '"ip protocol tcp ct state established,related,new accept" not in rhel9cis_3_4_3_5_outconnectionrule.stdout'

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add output udp new, related, established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" output ip protocol udp ct state new,related,established accept
        when: '"ip protocol udp ct state established,related,new accept" not in rhel9cis_3_4_3_5_outconnectionrule.stdout'

      - name: "3.4.3.5 | L1 | PATCH | Ensure nftables outbound and established connections are configured | Add output icmp new, related, established accept policy"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" output ip protocol icmp ct state new,related,established accept
        when: '"ip protocol icmp ct state established,related,new accept" not in rhel9cis_3_4_3_5_outconnectionrule.stdout'
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_5
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.5

- name: "3.4.3.6 | L1 | PATCH | Ensure nftables default deny firewall policy"
  block:
      - name: "3.4.3.6 | L1 | AUDIT | Ensure nftables default deny firewall policy | Check for hook input deny policy"
        shell: nft list table inet "{{ rhel9cis_nft_tables_tablename }}" | grep 'hook input'
        failed_when: false
        changed_when: false
        register: rhel9cis_3_4_3_6_inputpolicy

      - name: "3.4.3.6 | L1 | AUDIT | Ensure nftables default deny firewall policy | Check for hook forward deny policy"
        shell: nft list table inet "{{ rhel9cis_nft_tables_tablename }}" | grep 'hook forward'
        failed_when: false
        changed_when: false
        register: rhel9cis_3_4_3_6_forwardpolicy

      - name: "3.4.3.6 | L1 | AUDIT | Ensure nftables default deny firewall policy | Check for hook output deny policy"
        shell: nft list table inet "{{ rhel9cis_nft_tables_tablename }}" | grep 'hook output'
        failed_when: false
        changed_when: false
        register: rhel9cis_3_4_3_6_outputpolicy

      - name: "3.4.3.6 | L1 | AUDIT | Ensure nftables default deny firewall policy | Check for SSH allow"
        shell: nft list table inet "{{ rhel9cis_nft_tables_tablename }}" | grep 'ssh'
        failed_when: false
        changed_when: false
        register: rhel9cis_3_4_3_6_sshallowcheck

      - name: "3.4.3.6 | L1 | PATCH | Ensure nftables default deny firewall policy | Enable SSH traffic"
        command: nft add rule inet "{{ rhel9cis_nft_tables_tablename }}" input tcp dport ssh accept
        when: '"tcp dport ssh accept" not in rhel9cis_3_4_3_6_sshallowcheck.stdout'

      - name: "3.4.3.6 | L1 | PATCH | Ensure nftables default deny firewall policy | Set hook input deny policy"
        command: nft chain inet "{{ rhel9cis_nft_tables_tablename }}" input { policy drop \; }
        when: '"type filter hook input priority 0; policy drop;" not in rhel9cis_3_4_3_6_inputpolicy.stdout'

      - name: "3.4.3.6 | L1 | PATCH | Ensure nftables default deny firewall policy | Create hook forward deny policy"
        command: nft chain inet "{{ rhel9cis_nft_tables_tablename }}" forward { policy drop \; }
        when: '"type filter hook forward priority 0; policy drop;" not in rhel9cis_3_4_3_6_forwardpolicy.stdout'

      - name: "3.4.3.6 | L1 | PATCH | Ensure nftables default deny firewall policy | Create hook output deny policy"
        command: nft chain inet "{{ rhel9cis_nft_tables_tablename }}" output { policy drop \; }
        when: '"type filter hook output priority 0; policy drop;" not in rhel9cis_3_4_3_6_outputpolicy.stdout'
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_6
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.6

- name: "3.4.3.7 | L1 | PATCH | Ensure nftables service is enabled | Check if nftables is enabled"
  service:
      name: nftables
      enabled: yes
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_7
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.7

- name: "3.4.3.8 | L1 | PATCH | Ensure nftables rules are permanent"
  lineinfile:
      path: /etc/sysconfig/nftables.conf
      state: present
      insertafter: EOF
      line: include "/etc/nftables/inet-{{ rhel9cis_nft_tables_tablename }}"
  when:
      - rhel9cis_firewall == "nftables"
      - rhel9cis_rule_3_4_3_8
  tags:
      - level1-server
      - level1-workstation
      - patch
      - rule_3.4.3.8