Re: Confirm: letting certain packages pass through un-natted

[David Leangen <dleangen@canada.com>]

Ok, I'm obviously doing a horrible job at troubleshooting...

Here's the gist of my iptables rules on my router box 
192.168.1.2/192.168.2.1. I'm trying to figure out why machines on my 
local network can't communicate with 192.168.1.1.

BTW, don't even ask about the entries in the mangle table... I just 
copied them mindlessly. :-(


*mangle
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG 
FIN,PSH,URG -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j 
DROP
-A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG 
FIN,PSH,URG -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j 
DROP
-A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG 
FIN,PSH,URG -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j 
DROP
-A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG 
FIN,PSH,URG -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j 
DROP
-A PREROUTING -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -j DROP
-A PREROUTING -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
COMMIT

*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A PREROUTING -p tcp --dport 443 -j DNAT --to 192.168.2.2:443
-A POSTROUTING -d 192.168.2.2 -s 192.168.0.0/255.255.0.0 -p tcp --dport 
443 -j S
NAT --to 192.168.1.2
-A PREROUTING -p tcp --dport 8180 -j DNAT --to 192.168.2.10:8180
-A POSTROUTING -d 192.168.2.10 -s 192.168.0.0/255.255.0.0 -p tcp --dport 
8180 -j
  SNAT --to 192.168.1.2
-A PREROUTING -p tcp --dport 8182 -j DNAT --to 192.168.2.2:8182
-A POSTROUTING -d 192.168.2.2 -s 192.168.0.0/255.255.0.0 -p tcp --dport 
8182 -j
SNAT --to 192.168.1.2
-A POSTROUTING -o ppp0 -j MASQUERADE
COMMIT

*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:LOG_ACCEPT - [0:0]
:LOG_DROP - [0:0]
:icmp_packets - [0:0]
# I don't even think this next line is necessary, though, since the 
default policy is "ACCEPT"...
-A FORWARD -s 192.168.0.0/16 -d 192.168.1.1 -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j LOG_ACCEPT
# Open up some other ports (edited out)
-A INPUT -s 127.0.0.1 -j ACCEPT
-A INPUT -p icmp -j icmp_packets
-A INPUT -j LOG_DROP
-A LOG_ACCEPT -j LOG --log-prefix "[IPTABLES ACCEPT] : " 
--log-tcp-options --log
-ip-options
-A LOG_ACCEPT -j ACCEPT
-A LOG_DROP -j LOG --log-prefix "[IPTABLES DROP] : " --log-tcp-options 
--log-ip-
options
-A LOG_DROP -j DROP
-A icmp_packets -p icmp -m icmp --icmp-type 0 -j ACCEPT
-A icmp_packets -s 192.168.0.0/255.255.255.0 -p icmp -m icmp --icmp-type 
8 -j AC
CEPT
-A icmp_packets -s 192.168.1.0/255.255.255.0 -p icmp -m icmp --icmp-type 
8 -j AC
CEPT
-A icmp_packets -s 192.168.2.0/255.255.255.0 -p icmp -m icmp --icmp-type 
8 -j AC
CEPT
-A icmp_packets -p icmp -m icmp --icmp-type 8 -j ACCEPT
-A icmp_packets -p icmp -m icmp --icmp-type 3 -j ACCEPT
-A icmp_packets -p icmp -m icmp --icmp-type 11 -j ACCEPT
COMMIT