ansible/roles/firewall/templates/iptables.j2

*filter
:INPUT {{ firewall_iptables_input_policy }}
:FORWARD {{ firewall_iptables_forward_policy }}
:OUTPUT {{ firewall_iptables_output_policy }}

-N LOG_ACCEPT
-A LOG_ACCEPT -m limit --limit {{ firewall_log_limit }} --limit-burst {{ firewall_log_limit_burst }} -j LOG --log-prefix "[iptables ACCEPT] " --log-level info
-A LOG_ACCEPT -j ACCEPT

-N LOG_DROP
-A LOG_DROP -m limit --limit {{ firewall_log_limit }} --limit-burst {{ firewall_log_limit_burst }} -j LOG --log-prefix "[iptables DROP] " --log-level info
-A LOG_DROP -p tcp -m tcp -m comment --comment "reject tcp" -j REJECT --reject-with tcp-reset
-A LOG_DROP -p udp -m udp -m comment --comment "drop udp" -j DROP
-A LOG_DROP -m comment --comment "reject all" -j REJECT --reject-with icmp-admin-prohibited

{% if firewall_limit_ssh %}
-N LIMIT_SSH
-A LIMIT_SSH -m recent --set --name SSH --rsource
-A LIMIT_SSH -m recent --update --seconds {{ firewall_limit_ssh_seconds }} --hitcount {{ firewall_limit_ssh_hitcount }} --name SSH --rsource -m limit --limit {{ firewall_log_limit }} --limit-burst {{ firewall_log_limit_burst }} -j LOG --log-prefix "[iptables SSH BRUTE] " --log-level info
-A LIMIT_SSH -p tcp -m tcp -m recent --update --seconds {{ firewall_limit_ssh_seconds }} --hitcount {{ firewall_limit_ssh_hitcount }} --name SSH --rsource -m comment --comment "rate limit ssh v4" -j REJECT --reject-with tcp-reset
-A LIMIT_SSH -j ACCEPT
{% endif %}

{% if firewall_drop_icmp_flood %}
-N ICMP_FLOOD
-A ICMP_FLOOD -m recent --set --name ICMP --rsource
-A ICMP_FLOOD -m recent --update --seconds 1 --hitcount 6 --name ICMP --rsource --rttl -m limit --limit {{ firewall_log_limit }} --limit-burst {{ firewall_log_limit_burst }} -j LOG --log-prefix "[iptables ICMP FLOOD] " --log-level info
-A ICMP_FLOOD -m recent --update --seconds 1 --hitcount 6 --name ICMP --rsource --rttl -m comment --comment "drop icmp flood v4" -j REJECT --reject-with icmp-admin-prohibited
-A ICMP_FLOOD -j ACCEPT
{% endif %}

-A INPUT -i lo -m comment --comment "lo accept all" -j ACCEPT

-A INPUT -m state --state INVALID -m comment --comment "drop invalid IPv4" -j DROP

{% if firewall_ipset_mgmt.v4 is defined %}
-A INPUT -p tcp -m tcp --dport 22 -m set --match-set mgmt_v4 src -m comment --comment "accept mgmt ssh" -j ACCEPT
{% endif %}

{% if firewall_ipset_blacklist.v4 is defined %}
-A INPUT -m set --match-set mgmt_v4 src -m comment --comment "drop blacklist" -j LOG_DROP
{% endif %}

{% if firewall_ipset_bogons.v4 is defined %}
-A INPUT -i {{ firewall_bogon_interface }} -m set --match-set bogons_v4 src,dst -m comment --comment "drop bogons" -j LOG_DROP
{% endif %}

-A INPUT -p icmp -m icmp --icmp-type destination-unreachable -m comment --comment "accept icmp destination-unreachable" -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type time-exceeded -m comment --comment "accept icmp time-exceeded" -j ACCEPT
-A INPUT -p icmp -m icmp --icmp-type parameter-problem -m comment --comment "accept icmp parameter-problem" -j ACCEPT
{% if firewall_drop_icmp_flood %}
-A INPUT -p icmp -m icmp --icmp-type echo-request -m comment --comment "accept icmp echo-request" -j ICMP_FLOOD
{% else %}
-A INPUT -p icmp -m icmp --icmp-type echo-request -m comment --comment "accept icmp echo-request" -j ACCEPT
{% endif %}
-A INPUT -p icmp -m icmp --icmp-type echo-reply -m comment --comment "accept icmp echo-reply" -j ACCEPT

{% for type in firewall_allowed_icmp_types.v4 | default([]) %}
-A INPUT -p icmp -m icmp --icmp-type {{ type }} -m comment --comment "accept icmp {{ type }}" -j ACCEPT
{% endfor %}

{% if firewall_limit_ssh %}
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m comment --comment "accept ssh" -j LIMIT_SSH
{% else %}
-A INPUT -p tcp -m tcp --dport 22 -m state --state NEW -m comment --comment "accept ssh" -j ACCEPT
{% endif %}

{% for port in firewall_allowed_tcp_ports.v4 | default([]) %}
-A INPUT -p tcp -m tcp --dport {{ port }} -m comment --comment "accept {{ port }}/tcp" -j ACCEPT
{% endfor %}

{% for port in firewall_allowed_udp_ports.v4 | default([]) %}
-A INPUT -p udp -m udp --dport {{ port }} -m comment --comment "accept {{ port }}/udp" -j ACCEPT
{% endfor %}

-A INPUT -m state --state RELATED,ESTABLISHED -m comment --comment "accept related/established" -j ACCEPT

-A INPUT -m comment --comment "log drop" -j LOG_DROP

COMMIT