New iptables, no server. Hmm..
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Hi, I've just set up iptables based on Oskar Andreasson's template
(eth0/eth1, http://www.faqs.org/docs/iptables) but find I can't
connect to the server.
Luckily 'flush-iptables' is to hand.
I've added line 88 to log tcp options according to 'man psad'. Could
this have done it ?
I'd be grateful for any constructive comment (apologies Oskar).
Adam Bogacki,
afb@paradise.net.nz
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#!/bin/sh
INET_IP="192.168.0.1"
INET_IFACE="eth0"
INET_BROADCAST="192.168.0.100"
LAN_IP="192.168.0.2"
LAN_IP_RANGE="192.168.0.0/16"
LAN_IFACE="eth1"
LO_IFACE="lo"
LO_IP="127.0.0.1"
IPTABLES="/usr/sbin/iptables"
/sbin/depmod -a
/sbin/modprobe ip_tables
/sbin/modprobe ip_conntrack
/sbin/modprobe iptable_filter
/sbin/modprobe iptable_mangle
/sbin/modprobe iptable_nat
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_limit
/sbin/modprobe ipt_state
echo "1" > /proc/sys/net/ipv4/ip_forward
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP
iptables -N bad_tcp_packets
iptables -N allowed
iptables -N tcp_packets
iptables -N udp_packets
iptables -N icmp_packets
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
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
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
#$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 53 -j ACCEPT
#$IPTABLES -A udp_packets -p UDP -s 0/0 --destination-port 123 -j ACCEPT
iptables -A udp_packets -p UDP -s 0/0 --destination-port 2074 -j ACCEPT
iptables -A udp_packets -p UDP -s 0/0 --destination-port 4000 -j ACCEPT
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
iptables -A INPUT -p tcp -j bad_tcp_packets
iptables -A INPUT -p ALL -i $LAN_IFACE -s $LAN_IP_RANGE -j ACCEPT
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
iptables -A INPUT -p UDP -i $LAN_IFACE --dport 67 --sport 68 -j ACCEPT
iptables -A INPUT -p ALL -d $INET_IP -m state --state ESTABLISHED,RELATED \
-j ACCEPT
iptables -A INPUT -p TCP -i $INET_IFACE -j tcp_packets
iptables -A INPUT -p UDP -i $INET_IFACE -j udp_packets
iptables -A INPUT -p ICMP -i $INET_IFACE -j icmp_packets
iptables -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT INPUT packet died: "
iptables -A FORWARD -p tcp -j bad_tcp_packets
iptables -A FORWARD -i $LAN_IFACE -j ACCEPT
iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -p tcp -j LOG --log-tcp-options
iptables -A FORWARD -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT FORWARD packet died: "
iptables -A OUTPUT -p tcp -j bad_tcp_packets
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
iptables -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \
--log-level DEBUG --log-prefix "IPT OUTPUT packet died: "
iptables -t nat -A POSTROUTING -o $INET_IFACE -j SNAT --to-source $INET_IP
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