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120 lines
5.3 KiB
Django/Jinja
120 lines
5.3 KiB
Django/Jinja
{% set subnets = ([strongswan_network_ipv6] if ipsec_enabled else []) + ([wireguard_network_ipv6] if wireguard_enabled else []) %}
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{% set ports = (['500', '4500'] if ipsec_enabled else []) + ([wireguard_port] if wireguard_enabled else []) + ([wireguard_port_actual] if wireguard_enabled and wireguard_port|int == wireguard_port_avoid|int else []) %}
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#### The mangle table
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# This table allows us to modify packet headers
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# Packets enter this table first
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#
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*mangle
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:PREROUTING ACCEPT [0:0]
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:INPUT ACCEPT [0:0]
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:FORWARD ACCEPT [0:0]
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:OUTPUT ACCEPT [0:0]
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:POSTROUTING ACCEPT [0:0]
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{% if reduce_mtu|int > 0 and ipsec_enabled %}
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-A FORWARD -s {{ strongswan_network_ipv6 }} -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss {{ 1340 - reduce_mtu|int }}
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{% endif %}
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COMMIT
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#### The nat table
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# This table enables Network Address Translation
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# (This is technically a type of packet mangling)
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#
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*nat
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:PREROUTING ACCEPT [0:0]
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:POSTROUTING ACCEPT [0:0]
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{% if wireguard_enabled and wireguard_port|int == wireguard_port_avoid|int %}
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# Handle the special case of allowing access to WireGuard over an already used
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# port like 53
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-A PREROUTING --in-interface {{ ansible_default_ipv6['interface'] }} -p udp --dport {{ wireguard_port_avoid }} -j REDIRECT --to-port {{ wireguard_port_actual }}
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{% endif %}
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# Allow traffic from the VPN network to the outside world, and replies
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-A POSTROUTING -s {{ subnets|join(',') }} -m policy --pol none --dir out -j SNAT --to {{ ipv6_egress_ip | ipaddr('address') }}
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COMMIT
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#### The filter table
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# The default ipfilter table
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#
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*filter
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# By default, drop packets that are destined for this server
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:INPUT DROP [0:0]
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# By default, drop packets that request to be forwarded by this server
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:FORWARD DROP [0:0]
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# By default, accept any packets originating from this server
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:OUTPUT ACCEPT [0:0]
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# Create the ICMPV6-CHECK chain and its log chain
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# These chains are used later to prevent a type of bug that would
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# allow malicious traffic to reach over the server into the private network
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# An instance of such a bug on Cisco software is described here:
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# https://www.insinuator.net/2016/05/cve-2016-1409-ipv6-ndp-dos-vulnerability-in-cisco-software/
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# other software implementations might be at least as broken as the one in CISCO gear.
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:ICMPV6-CHECK - [0:0]
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:ICMPV6-CHECK-LOG - [0:0]
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# Accept packets destined for localhost
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-A INPUT -i lo -j ACCEPT
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# Accept any packet from an open TCP connection
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-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
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# Accept packets using the encapsulation protocol
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-A INPUT -p esp -j ACCEPT
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-A INPUT -m ah -j ACCEPT
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# rate limit ICMP traffic per source
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-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
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# Accept IPSEC/WireGuard traffic to ports {{ subnets|join(',') }}
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-A INPUT -p udp -m multiport --dports {{ ports|join(',') }} -j ACCEPT
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# Allow new traffic to port {{ ansible_ssh_port }} (SSH)
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-A INPUT -p tcp --dport {{ ansible_ssh_port }} -m conntrack --ctstate NEW -j ACCEPT
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# Accept properly formatted Neighbor Discovery Protocol packets
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-A INPUT -p icmpv6 --icmpv6-type router-advertisement -m hl --hl-eq 255 -j ACCEPT
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-A INPUT -p icmpv6 --icmpv6-type neighbor-solicitation -m hl --hl-eq 255 -j ACCEPT
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-A INPUT -p icmpv6 --icmpv6-type neighbor-advertisement -m hl --hl-eq 255 -j ACCEPT
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-A INPUT -p icmpv6 --icmpv6-type redirect -m hl --hl-eq 255 -j ACCEPT
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# DHCP in AWS
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-A INPUT -m conntrack --ctstate NEW -m udp -p udp --dport 546 -d fe80::/64 -j ACCEPT
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# TODO:
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# The IP of the resolver should be bound to a DUMMY interface.
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# DUMMY interfaces are the proper way to install IPs without assigning them any
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# particular virtual (tun,tap,...) or physical (ethernet) interface.
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# Accept DNS traffic to the local DNS resolver
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-A INPUT -d {{ local_service_ipv6 }}/128 -p udp --dport 53 -j ACCEPT
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# Drop traffic between VPN clients
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-A FORWARD -s {{ subnets|join(',') }} -d {{ subnets|join(',') }} -j {{ "DROP" if BetweenClients_DROP else "ACCEPT" }}
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# Drop traffic to VPN clients from SSH tunnels
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-A OUTPUT -d {{ subnets|join(',') }} -m owner --gid-owner 15000 -j {{ "DROP" if BetweenClients_DROP else "ACCEPT" }}
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-A FORWARD -j ICMPV6-CHECK
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-A FORWARD -p tcp --dport 445 -j {{ "DROP" if block_smb else "ACCEPT" }}
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-A FORWARD -p udp -m multiport --ports 137,138 -j {{ "DROP" if block_netbios else "ACCEPT" }}
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-A FORWARD -p tcp -m multiport --ports 137,139 -j {{ "DROP" if block_netbios else "ACCEPT" }}
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-A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
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{% if ipsec_enabled %}
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-A FORWARD -m conntrack --ctstate NEW -s {{ strongswan_network_ipv6 }} -m policy --pol ipsec --dir in -j ACCEPT
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{% endif %}
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{% if wireguard_enabled %}
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-A FORWARD -m conntrack --ctstate NEW -s {{ wireguard_network_ipv6 }} -m policy --pol none --dir in -j ACCEPT
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{% endif %}
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# Use the ICMPV6-CHECK chain, described above
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-A ICMPV6-CHECK -p icmpv6 -m hl ! --hl-eq 255 --icmpv6-type router-solicitation -j ICMPV6-CHECK-LOG
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-A ICMPV6-CHECK -p icmpv6 -m hl ! --hl-eq 255 --icmpv6-type router-advertisement -j ICMPV6-CHECK-LOG
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-A ICMPV6-CHECK -p icmpv6 -m hl ! --hl-eq 255 --icmpv6-type neighbor-solicitation -j ICMPV6-CHECK-LOG
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-A ICMPV6-CHECK -p icmpv6 -m hl ! --hl-eq 255 --icmpv6-type neighbor-advertisement -j ICMPV6-CHECK-LOG
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-A ICMPV6-CHECK-LOG -j LOG --log-prefix "ICMPV6-CHECK-LOG DROP "
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-A ICMPV6-CHECK-LOG -j DROP
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COMMIT
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