Hello, I'm looking for suggestions on my iptables rule set.
There are three interfaces in this server: eth0 - <internet-address> eth1 - <lan-address> eth2 - <dmz-address> ### Create Chains iptables -N IN_LO iptables -N OUT_LO iptables -N IN_ETH0 iptables -N OUT_ETH0 iptables -N IN_ETH1 iptables -N OUT_ETH1 iptables -N IN_ETH2 iptables -N OUT_ETH2 iptables -N BLOCKED_PACKETS iptables -N ICMP_PACKETS ### POLICIES iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP ### INPUT iptables -A INPUT -j BLOCKED_PACKETS iptables -A INPUT -p icmp -j ICMP_PACKETS iptables -A INPUT -i lo -j IN_LO iptables -A INPUT -i eth0 -j IN_ETH0 iptables -A INPUT -i eth1 -j IN_ETH1 iptables -A INPUT -i eth2 -j IN_ETH2 ### FORWARD iptables -A FORWARD -j BLOCKED_PACKETS iptables -A FORWARD -p icmp -j ICMP_PACKETS iptables -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT ### OUTPUT iptables -A OUTPUT -j BLOCKED_PACKETS iptables -A OUTPUT -p icmp -j ICMP_PACKETS iptables -A OUTPUT -o lo -j OUT_LO iptables -A OUTPUT -o eth0 -j OUT_ETH0 iptables -A OUTPUT -o eth1 -j OUT_ETH1 iptables -A OUTPUT -o eth2 -j OUT_ETH2 ### BLOCKING_PACKETS iptables -A BLOCKED_PACKETS -m state --state INVALID -j DROP iptables -A BLOCKED_PACKETS -p tcp -m tcp --tcp-flags SYN,ACK \ SYN,ACK -m state --state NEW -j REJECT --reject-with tcp-reset iptables -A BLOCKED_PACKETS -p tcp ! --syn -m state --state NEW \ -j DROP iptables -A BLOCKED_PACKETS -d 224.0.0.0/8 -j DROP # should this be all three interfaces? iptables -A BLOCKED_PACKETS -d <internet-broadcast> -i eth0 -p udp \ --dport 135:139 -j DROP iptables -A BLOCKED_PACKETS -d 255.255.255.255 -i eth0 -p udp \ --dport 67:68 -j DROP ### ICMP_PACKETS # are all of these really needed? Which ones should I not accept? iptables -A ICMP_PACKETS -p icmp --icmp-type 0 -j ACCEPT iptables -A ICMP_PACKETS -p icmp --icmp-type 3 -j ACCEPT iptables -A ICMP_PACKETS -p icmp --icmp-type 4 -j ACCEPT iptables -A ICMP_PACKETS -p icmp --icmp-type 8 -j ACCEPT iptables -A ICMP_PACKETS -p icmp --icmp-type 11 -j ACCEPT iptables -A ICMP_PACKETS -p icmp --icmp-type 12 -j ACCEPT ### IN_LO (localhost) # are these really needed? Why? iptables -A IN_LO -s 127.0.0.1 -i lo -j ACCEPT iptables -A IN_LO -s <lan-address> -i lo -j ACCEPT iptables -A IN_LO -s <dmz-address> -i lo -j ACCEPT iptables -A IN_LO -s <internet-address> -i lo -j ACCEPT ### IN_ETH0 (Internet) iptables -A IN_ETH0 -d <internet-address> -i eth0 -m state \ --state RELATED,ESTABLISHED -j ACCEPT ### IN_ETH1 (LAN) iptables -A IN_ETH1 -d <lan-address> -i eth1 -m state \ --state RELATED,ESTABLISHED -j ACCEPT ### IN_ETH2 (DMZ) iptables -A IN_ETH2 -d <dmz-address> -i eth2 -m state \ --state RELATED,ESTABLISHED -j ACCEPT ### OUT_LO (Localhost) # are these really needed? Why? iptables -A OUT_LO -d 127.0.0.1 -o lo -j ACCEPT iptables -A OUT_LO -d <lan-address> -o lo -j ACCEPT iptables -A OUT_LO -d <dmz-address> -o lo -j ACCEPT iptables -A OUT_LO -d <internet-address> -o lo -j ACCEPT ### OUT_ETH0 (Internet) iptables -A OUT_ETH0 -s <internet-address> -o eth0 -m state \ --state RELATED,ESTABLISHED -j ACCEPT ### OUT_ETH1 (LAN) iptables -A OUT_ETH1 -s <lan-address> -o eth1 -m state \ --state RELATED,ESTABLISHED -j ACCEPT ### OUT_ETH2 (DMZ) iptables -A OUT_ETH2 -d <dmz-address> -o eth2 -m state \ --state RELATED,ESTABLISHED -j ACCEPT Specific Services: ------------------ ### DNS iptables -t nat -A PREROUTING -d <dns-internet-IP> -p tcp \ --dport 53 -j DNAT --to-destination <dns-DMZ-IP> iptables -t nat -A PREROUTING -d <dns-internet-IP> -p udp \ --dport 53 -j DNAT --to-destination <dns-DMZ-IP> iptables -A FORWARD -d <dns-DMZ-IP> -p tcp --syn --dport 53 \ -m state --state NEW -j ACCEPT iptables -A FORWARD -d <dns-DMZ-IP> -p udp --dport 53 -m state \ --state NEW -j ACCEPT iptables -t nat -A POSTROUTING -s <dns-DMZ-IP> -p tcp --sport 53 \ -j SNAT --to-source <dns-internet-IP> iptables -t nat -A POSTROUTING -s <dns-DMZ-IP> -p udp --sport 53 \ -j SNAT --to-source <dns-internet-IP> ### FTP iptables -t nat -A PREROUTING -d <ftp-internet-IP> -p tcp \ --dport 21 -j DNAT --to-destination <ftp-DMZ-IP> iptables -A FORWARD -d <ftp-DMZ-IP> -p tcp --syn --dport 21 \ -m state --state NEW -j ACCEPT iptables -t nat -A POSTROUTING -s <ftp-DMZ-IP> -p tcp --sport 21 \ -j SNAT --to-source <ftp-internet-IP> # I have other services, but if these are right I should be fine What about these two lines? - iptables -A INPUT -i eth2 -d <dmz-address> -j ACCEPT - iptables -A INPUT -i eth1 -d <lan-address> -j ACCEPT Thanks, Joseph
