Дефолтные настройки фаервола на mikrotik:
/ip firewall address-list add address=0.0.0.0/8 comment="Self-Identification [RFC 3330]" disabled=no list=bogons add address=10.0.0.0/8 comment="Private[RFC 1918] - CLASS A # Check if you need this subnet before enable it"\ disabled=yes list=bogons add address=127.0.0.0/8 comment="Loopback [RFC 3330]" disabled=no list=bogons add address=169.254.0.0/16 comment="Link Local [RFC 3330]" disabled=no list=bogons add address=172.16.0.0/12 comment="Private[RFC 1918] - CLASS B # Check if you need this subnet before enable it"\ disabled=yes list=bogons add address=192.168.0.0/16 comment="Private[RFC 1918] - CLASS C # Check if you need this subnet before enable it"\ disabled=yes list=bogons add address=192.0.2.0/24 comment="Reserved - IANA - TestNet1" disabled=no list=bogons add address=192.88.99.0/24 comment="6to4 Relay Anycast [RFC 3068]" disabled=no list=bogons add address=198.18.0.0/15 comment="NIDB Testing" disabled=no list=bogons add address=198.51.100.0/24 comment="Reserved - IANA - TestNet2" disabled=no list=bogons add address=203.0.113.0/24 comment="Reserved - IANA - TestNet3" disabled=no list=bogons add address=224.0.0.0/4 comment="MC, Class D, IANA # Check if you need this subnet before enable it"\ disabled=yes list=bogons /ip firewall filter add action=add-src-to-address-list address-list=Syn_Flooder address-list-timeout=30m chain=input \ comment="Add Syn Flood IP to the list" connection-limit=30,32 disabled=no protocol=tcp tcp-flags=syn add action=drop chain=input comment="Drop to syn flood list" disabled=no src-address-list=Syn_Flooder add action=add-src-to-address-list address-list=Port_Scanner address-list-timeout=1w chain=input comment="Port Scanner Detect"\ disabled=no protocol=tcp psd=21,3s,3,1 add action=drop chain=input comment="Drop to port scan list" disabled=no src-address-list=Port_Scanner add action=jump chain=input comment="Jump for icmp input flow" disabled=no jump-target=ICMP protocol=icmp add action=drop chain=input\ comment="Block all access to the winbox - except to support list # DO NOT ENABLE THIS RULE BEFORE ADD YOUR SUBNET IN THE SUPPORT ADDRESS LIST"\ disabled=yes dst-port=8291 protocol=tcp src-address-list=!support add action=jump chain=forward comment="Jump for icmp forward flow" disabled=no jump-target=ICMP protocol=icmp add action=drop chain=forward comment="Drop to bogon list" disabled=no dst-address-list=bogons add action=add-src-to-address-list address-list=spammers address-list-timeout=3h chain=forward comment="Add Spammers to the list for 3 hours" connection-limit=30,32 disabled=no dst-port=25,587 limit=30/1m,0:packet protocol=tcp add action=drop chain=forward comment="Avoid spammers action" disabled=no dst-port=25,587 protocol=tcp src-address-list=spammers add action=accept chain=input comment="Accept DNS - UDP" disabled=no port=53 protocol=udp add action=accept chain=input comment="Accept DNS - TCP" disabled=no port=53 protocol=tcp add action=accept chain=input comment="Accept to established connections" connection-state=established\ disabled=no add action=accept chain=input comment="Accept to related connections" connection-state=related disabled=no add action=accept chain=input comment="Full access to SUPPORT address list" disabled=no src-address-list=support add action=drop chain=input comment="Drop anything else! # DO NOT ENABLE THIS RULE BEFORE YOU MAKE SURE ABOUT ALL ACCEPT RULES YOU NEED"\ disabled=yes add action=accept chain=ICMP comment="Echo request - Avoiding Ping Flood" disabled=no icmp-options=8:0 limit=1,5:packet protocol=icmp add action=accept chain=ICMP comment="Echo reply" disabled=no icmp-options=0:0 protocol=icmp add action=accept chain=ICMP comment="Time Exceeded" disabled=no icmp-options=11:0 protocol=icmp add action=accept chain=ICMP comment="Destination unreachable" disabled=no icmp-options=3:0-1 protocol=icmp add action=accept chain=ICMP comment=PMTUD disabled=no icmp-options=3:4 protocol=icmp add action=drop chain=ICMP comment="Drop to the other ICMPs" disabled=no protocol=icmp add action=jump chain=output comment="Jump for icmp output" disabled=no jump-target=ICMP protocol=icmp
Источник: http://wiki.mikrotik.com/wiki/Basic_universal_firewall_script