Block all incoming traffic but

Author: AbrahamAlgorithm

0x13-firewall/0-block_all_incoming_traffic_but

@@ -0,0 +1,80 @@
+#
+# rules.before
+#
+# Rules that should be run before the ufw command line added rules. Custom
+# rules should be added to one of these chains:
+#   ufw-before-input
+#   ufw-before-output
+#   ufw-before-forward
+#
+
+*nat
+:PREROUTING ACCEPT [0:0]
+-A PREROUTING -p tcp --dport 8080 -j REDIRECT --to-port 80
+COMMIT
+
+# Don't delete these required lines, otherwise there will be errors
+*filter
+:ufw-before-input - [0:0]
+:ufw-before-output - [0:0]
+:ufw-before-forward - [0:0]
+:ufw-not-local - [0:0]
+# End required lines
+
+
+# allow all on loopback
+-A ufw-before-input -i lo -j ACCEPT
+-A ufw-before-output -o lo -j ACCEPT
+
+# quickly process packets for which we already have a connection
+-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+-A ufw-before-output -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
+
+# drop INVALID packets (logs these in loglevel medium and higher)
+-A ufw-before-input -m conntrack --ctstate INVALID -j ufw-logging-deny
+-A ufw-before-input -m conntrack --ctstate INVALID -j DROP
+
+# ok icmp codes for INPUT
+-A ufw-before-input -p icmp --icmp-type destination-unreachable -j ACCEPT
+-A ufw-before-input -p icmp --icmp-type time-exceeded -j ACCEPT
+-A ufw-before-input -p icmp --icmp-type parameter-problem -j ACCEPT
+-A ufw-before-input -p icmp --icmp-type echo-request -j ACCEPT
+
+# ok icmp code for FORWARD
+-A ufw-before-forward -p icmp --icmp-type destination-unreachable -j ACCEPT
+-A ufw-before-forward -p icmp --icmp-type time-exceeded -j ACCEPT
+-A ufw-before-forward -p icmp --icmp-type parameter-problem -j ACCEPT
+-A ufw-before-forward -p icmp --icmp-type echo-request -j ACCEPT
+
+# allow dhcp client to work
+-A ufw-before-input -p udp --sport 67 --dport 68 -j ACCEPT
+
+#
+# ufw-not-local
+#
+-A ufw-before-input -j ufw-not-local
+
+# if LOCAL, RETURN
+-A ufw-not-local -m addrtype --dst-type LOCAL -j RETURN
+
+# if MULTICAST, RETURN
+-A ufw-not-local -m addrtype --dst-type MULTICAST -j RETURN
+
+# if BROADCAST, RETURN
+-A ufw-not-local -m addrtype --dst-type BROADCAST -j RETURN
+
+# all other non-local packets are dropped
+-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j ufw-logging-deny
+-A ufw-not-local -j DROP
+
+# allow MULTICAST mDNS for service discovery (be sure the MULTICAST line above
+# is uncommented)
+-A ufw-before-input -p udp -d 224.0.0.251 --dport 5353 -j ACCEPT
+
+# allow MULTICAST UPnP for service discovery (be sure the MULTICAST line above
+# is uncommented)
+-A ufw-before-input -p udp -d 239.255.255.250 --dport 1900 -j ACCEPT
+
+# don't delete the 'COMMIT' line or these rules won't be processed
+COMMIT