Iptables Tutorial 1.1.19
Шрифт:
# 4.1.3 Create content in userspecified chains
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# bad_tcp_packets chain
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$IPTABLES -A bad_tcp_packets -p tcp –tcp-flags SYN,ACK SYN,ACK \
–m state –state NEW -j REJECT –reject-with tcp-reset
$IPTABLES -A bad_tcp_packets -p tcp ! –syn -m state –state NEW -j LOG \
–log-prefix «New not syn:»
$IPTABLES -A bad_tcp_packets -p tcp ! –syn -m state –state NEW -j DROP
#
# allowed chain
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$IPTABLES -A allowed -p TCP –syn -j ACCEPT
$IPTABLES -A allowed -p TCP -m state –state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A allowed -p TCP -j DROP
#
# TCP rules
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$IPTABLES -A tcp_packets -p TCP -s 0/0 –dport 21 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 –dport 22 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 –dport 80 -j allowed
$IPTABLES -A tcp_packets -p TCP -s 0/0 –dport 113 -j allowed
#
# UDP ports
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#$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 53 -j ACCEPT
#$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 123 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 2074 -j ACCEPT
$IPTABLES -A udp_packets -p UDP -s 0/0 –source-port 4000 -j ACCEPT
#
# In Microsoft Networks you will be swamped by broadcasts. These lines
# will prevent them from showing up in the logs.
#
#$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d $INET_BROADCAST \
#–destination-port 135:139 -j DROP
#
# If we get DHCP requests from the Outside of our network, our logs will
# be swamped as well. This rule will block them from getting logged.
#
#$IPTABLES -A udp_packets -p UDP -i $INET_IFACE -d 255.255.255.255 \
#–destination-port 67:68 -j DROP
#
# ICMP rules
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$IPTABLES -A icmp_packets -p ICMP -s 0/0 –icmp-type 8 -j ACCEPT
$IPTABLES -A icmp_packets -p ICMP -s 0/0 –icmp-type 11 -j ACCEPT
#
# 4.1.4 INPUT chain
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#
# Bad TCP packets we don't want.
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$IPTABLES -A INPUT -p tcp -j bad_tcp_packets
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# Rules for special networks not part of the Internet
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$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LO_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $LAN_IP -j ACCEPT
$IPTABLES -A INPUT -p ALL -i $LO_IFACE -s $INET_IP -j ACCEPT
#
# Rules for incoming packets from anywhere.
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$IPTABLES -A INPUT -p ALL -d $INET_IP -m state –state ESTABLISHED,RELATED \
–j ACCEPT
$IPTABLES -A INPUT -p TCP -j tcp_packets
$IPTABLES -A INPUT -p UDP -j udp_packets
$IPTABLES -A INPUT -p ICMP -j icmp_packets
#
# If you have a Microsoft Network on the outside of your firewall, you may
# also get flooded by Multicasts. We drop them so we do not get flooded by
# logs
#
#$IPTABLES -A INPUT -i $INET_IFACE -d 224.0.0.0/8 -j DROP
#
# Log weird packets that don't match the above.
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$IPTABLES -A INPUT -m limit –limit 3/minute –limit-burst 3 -j LOG \
–log-level DEBUG –log-prefix "IPT INPUT packet died: "
#
# 4.1.5 FORWARD chain
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#
# Bad TCP packets we don't want
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$IPTABLES -A FORWARD -p tcp -j bad_tcp_packets
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# Accept the packets we actually want to forward
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$IPTABLES -A FORWARD -p tcp –dport 21 -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -p tcp –dport 80 -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -p tcp –dport 110 -i $LAN_IFACE -j ACCEPT
$IPTABLES -A FORWARD -m state –state ESTABLISHED,RELATED -j ACCEPT
#
# Log weird packets that don't match the above.
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$IPTABLES -A FORWARD -m limit –limit 3/minute –limit-burst 3 -j LOG \
–log-level DEBUG –log-prefix "IPT FORWARD packet died: "
#
# 4.1.6 OUTPUT chain
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#
# Bad TCP packets we don't want.
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$IPTABLES -A OUTPUT -p tcp -j bad_tcp_packets
#
# Special OUTPUT rules to decide which IP's to allow.
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$IPTABLES -A OUTPUT -p ALL -s $LO_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $LAN_IP -j ACCEPT
$IPTABLES -A OUTPUT -p ALL -s $INET_IP -j ACCEPT
#
# Log weird packets that don't match the above.
#
$IPTABLES -A OUTPUT -m limit –limit 3/minute –limit-burst 3 -j LOG \
–log-level DEBUG –log-prefix "IPT OUTPUT packet died: "
######
# 4.2 nat table
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