Overview
We strongly suggest keeping the default firewall on. Here are a few adjustments to make it more secure. Make sure you configure additional changes when you completely understand the benefit of these particular firewall rules.
To see the default firewall rules through the CLI you can type:
/system default configuration print
Ipv4 firewall
Protect the router itself
- work with new connections to decrease load on a router;
- create address-list for IP addresses, that are allowed to access your router;
- enable ICMP access (optionally);
- drop everything else, log=yes might be added to log packets that hit the specific rule;
/ip firewall filter add action=accept chain=input comment="default configuration" connection-state=established,related add action=accept chain=input src-address-list=allowed_to_router add action=accept chain=input protocol=icmp add action=drop chain=input /ip firewall address-list add address=192.168.88.2-192.168.88.254 list=allowed_to_router
Protect the LAN devices
- established/related packets are added to FastTrack for faster data throughput, firewall will work with new connections only;
- drop invalid connection and log them with prefix invalid;
- drop attempts to reach not public addresses from your local network, apply address-list=not_in_internet before, bridge1 is local network interface, log attempts with !public_from_LAN;
- drop incoming packets that are not NATed, ether1 is public interface, log attempts with !NAT prefix;
- drop incoming packets from the Internet, which are not public IP addresses, ether1 is public interface, log attempts with prefix !public;
- drop packets from LAN that does not have LAN IP, 192.168.88.0/24 is local network used subnet;
/ip firewall filter add action=fasttrack-connection chain=forward comment=FastTrack connection-state=established,related add action=accept chain=forward comment="Established, Related" connection-state=established,related add action=drop chain=forward comment="Drop invalid" connection-state=invalid log=yes log-prefix=invalid add action=drop chain=forward comment="Drop tries to reach not public addresses from LAN" dst-address-list=not_in_internet in-interface=bridge1 log=yes log-prefix=!public_from_LAN out-interface=!bridge1 add action=drop chain=forward comment="Drop incoming packets that are not NATted" connection-nat-state=!dstnat connection-state=new in-interface=ether1 log=yes log-prefix=!NAT add action=drop chain=forward comment="Drop incoming from internet which is not public IP" in-interface=ether1 log=yes log-prefix=!public src-address-list=not_in_internet add action=drop chain=forward comment="Drop packets from LAN that do not have LAN IP" in-interface=bridge1 log=yes log-prefix=LAN_!LAN src-address=!192.168.88.0/24
/ip firewall address-list add address=0.0.0.0/8 comment=RFC6890 list=not_in_internet add address=172.16.0.0/12 comment=RFC6890 list=not_in_internet add address=192.168.0.0/16 comment=RFC6890 list=not_in_internet add address=10.0.0.0/8 comment=RFC6890 list=not_in_internet add address=169.254.0.0/16 comment=RFC6890 list=not_in_internet add address=127.0.0.0/8 comment=RFC6890 list=not_in_internet add address=224.0.0.0/4 comment=Multicast list=not_in_internet add address=198.18.0.0/15 comment=RFC6890 list=not_in_internet add address=192.0.0.0/24 comment=RFC6890 list=not_in_internet add address=192.0.2.0/24 comment=RFC6890 list=not_in_internet add address=198.51.100.0/24 comment=RFC6890 list=not_in_internet add address=203.0.113.0/24 comment=RFC6890 list=not_in_internet add address=100.64.0.0/10 comment=RFC6890 list=not_in_internet add address=240.0.0.0/4 comment=RFC6890 list=not_in_internet add address=192.88.99.0/24 comment="6to4 relay Anycast [RFC 3068]" list=not_in_internet
IPv6 firewall
Protect the router itself
- work with new packets, accept established/related packets;
- drop link-local addresses from Internet interface;
- accept access to a router from link-local addresses, accept multicast addresses for management purposes, accept your address for router access;
- drop anything else;
/ipv6 firewall filter add action=accept chain=input comment="allow established and related" connection-state=established,related add chain=input action=accept protocol=icmpv6 comment="accept ICMPv6" add chain=input action=accept protocol=udp port=33434-33534 comment="defconf: accept UDP traceroute" add chain=input action=accept protocol=udp dst-port=546 src-address=fe80::/16 comment="accept DHCPv6-Client prefix delegation." add action=drop chain=input in-interface=sit1 log=yes log-prefix=dropLL_from_public src-address=fe80::/16 add action=accept chain=input comment="allow allowed addresses" src-address-list=allowed add action=drop chain=input /ipv6 firewall address-list add address=fe80::/16 list=allowed add address=xxxx::/48 list=allowed add address=ff02::/16 comment=multicast list=allowed
Protect the LAN devices
Enabled IPv6 puts your clients available for public networks, set proper firewall to protect your customers.
- accept established/related and work with new packets;
- drop invalid packets and put prefix for rules;
- accept ICMP packets;
- accept new connection from your clients to the Internet;
- drop everything else.
/ipv6 firewall filter add action=accept chain=forward comment=established,related connection-state=established,related add action=drop chain=forward comment=invalid connection-state=invalid log=yes log-prefix=ipv6,invalid add action=accept chain=forward comment=icmpv6 in-interface=!sit1 protocol=icmpv6 add action=accept chain=forward comment="local network" in-interface=!sit1 src-address-list=allowed add action=drop chain=forward log-prefix=IPV6