source: lab.git/iptables/ufw/before.rules @ 46dc3f4

#
# 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
#

# 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 -i lo -j ACCEPT

# connection tracking rules
-A ufw-before-input -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A ufw-before-forward -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT

# drop INVALID packets
# uncomment to log INVALID packets
-A ufw-before-input -m conntrack --ctstate INVALID -j LOG --log-prefix "[UFW BLOCK INVALID]: " --log-level err -m limit --limit 3/min --limit-burst 10
-A ufw-before-input -m conntrack --ctstate INVALID -j DROP

## Ingress filter (see RFC 2827) (eth0:LAN<192.168.100.0/24>)
-A ufw-before-forward -i eth0 -s ! 192.168.100.0/24 -j LOG --log-tcp-options --log-ip-options --log-prefix "[UFW BLOCK LOG_INGRESS]: " --log-level err -m limit --limit 3/min --limit-burst 10
-A ufw-before-forward -i eth0 -s ! 192.168.100.0/24 -j DROP

## DROP CIFS(Samba) access from/to WAN(eth1)
-A ufw-before-input   -i eth1 -p tcp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-input   -i eth1 -p udp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-forward -i eth1 -p tcp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-forward -i eth1 -p udp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-forward -o eth1 -p tcp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-forward -o eth1 -p udp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-output  -o eth1 -p tcp -m multiport --dports 135,137:139,445 -j DROP
-A ufw-before-output  -o eth1 -p udp -m multiport --dports 135,137:139,445 -j DROP

## Access from LAN
-A ufw-before-input -i eth0 -j ACCEPT
-A ufw-before-forward -i eth0 -j ACCEPT

# connection tracking for outbound
-A ufw-before-output -p tcp -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
-A ufw-before-output -p udp -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

# ok icmp codes
-A ufw-before-input -p icmp --icmp-type destination-unreachable -j ACCEPT
-A ufw-before-input -p icmp --icmp-type source-quench -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

# 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

-A ufw-not-local -m limit --limit 3/min --limit-burst 10 -j LOG --log-prefix "[UFW BLOCK NOT-TO-ME]: " --log-level err

# all other non-local packets are dropped
-A ufw-not-local -j DROP

# allow MULTICAST, be sure the MULTICAST line above is uncommented
-A ufw-before-input -s 224.0.0.0/4 -j ACCEPT
-A ufw-before-input -d 224.0.0.0/4 -j ACCEPT


# don't delete the 'COMMIT' line or these rules won't be processed
COMMIT