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{{ ansible_managed | comment }}
*filter
# By default, drop incoming packets:
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
# By default, accept outgoing packets:
:OUTPUT ACCEPT [0:0]
# Accept packets for localhost:
-A INPUT -i lo -j ACCEPT
# Accept any packet for an open connection:
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# The SSH port is always open:
{% set ssh_port = hostvars[inventory_hostname].ansible_port %}
# Open TCP ports:
{% set tcp_ports = [ssh_port] + firewall_ports_tcp + firewall_ports6_tcp %}
{% set tcp_ports = tcp_ports | unique %}
{% for port in tcp_ports %}
{% set num = port.port if port.port is defined else port %}
{% set src = '-s ' + port.source if port.source is defined else '' %}
-A INPUT -p tcp {{ src }} --dport {{ num }} -m conntrack --ctstate NEW -j ACCEPT
{% endfor %}
# Open UDP ports:
{% set udp_ports = firewall_ports_udp + firewall_ports6_udp %}
{% set udp_ports = udp_ports | unique %}
{% for port in udp_ports %}
{% set num = port.port if port.port is defined else port %}
{% set src = '-s ' + port.source if port.source is defined else '' %}
-A INPUT -p udp {{ src }} --dport {{ num }} -j ACCEPT
{% endfor %}
# Any additional IPv6 rules:
{{ firewall_rules6 | join('\n') }}
# ICMP; allow only pings and rate-limit them:
-A INPUT -p icmpv6 --icmpv6-type echo-request -m hashlimit --hashlimit-upto 5/s --hashlimit-mode srcip --hashlimit-srcmask 32 --hashlimit-name icmp-echo-drop -j ACCEPT
# ICMP; IPv6 stuff. To be honest, I don't really understand it; this was copied
# from trailofbits/algo's rules.v6 template at
#
# https://github.com/trailofbits/algo/blob/master/roles/common/templates/rules.v6.j2
#
-A INPUT -p icmpv6 --icmpv6-type router-advertisement -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p icmpv6 --icmpv6-type neighbor-solicitation -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p icmpv6 --icmpv6-type neighbor-advertisement -m hl --hl-eq 255 -j ACCEPT
-A INPUT -p icmpv6 --icmpv6-type redirect -m hl --hl-eq 255 -j ACCEPT
# Log denies (this must be at the bottom of the file):
-A INPUT -m limit --limit 3/min -j LOG --log-prefix "iptables denied: " --log-level 4
COMMIT
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