Restrictive linux server firewall

#!/bin/sh
#Tight rc.firewall configuration
#Author - Avinash Duduskar 15/03/06
#This uses a dynamic flatfile called /etc/hosts.deny as a block list
touch /etc/hosts.deny

# Define our interface, static IP and DNS servers to tighten UDP
IP="66.141.68.217"
INT="eth0"
DNS1="151.164.23.201"
DNS2="151.164.1.8"
IPT="/usr/sbin/iptables"

## Flush and delete tables, states and disable forwarding

$IPT -F
$IPT -X

echo "0" > /proc/sys/net/ipv4/ip_forward


## Default chain policies - DROP ALL IN & OUT; ALLOW lo

$IPT -P INPUT DROP
$IPT -P OUTPUT DROP
$IPT -P FORWARD DROP
$IPT -A INPUT -i lo -j ACCEPT
$IPT -A OUTPUT -o lo -j ACCEPT
$IPT -A INPUT -s $IP -i $INT -j DROP
$IPT -A INPUT -s 127.0.0.1 -i $INT -j DROP



# Log SSH and other SYN|ACKs so we have logs of all successful completed connections

$IPT -N SYNACK
$IPT -A SYNACK -j LOG --log-level debug
$IPT -A SYNACK -j ACCEPT
#$IPT -A INPUT -j LOG --log-level debug
#$IPT -A OUTPUT -j LOG --log-level debug

#$IPT -A OUTPUT -p tcp --sport 22 --tcp-flags ALL SYN,ACK -j LOG \
#    --log-level debug --log-prefix "SSH LOGIN: "

#$IPT -A OUTPUT -p tcp ! --sport 22 --tcp-flags ALL SYN,ACK -j LOG \
#    --log-level debug --log-prefix "3-SYN-ACK: "
   
#$IPT -A INPUT -m tcp -p tcp ! --syn -m state --state NEW -j LOG \
#    --log-level debug --log-prefix "New not syn: "

$IPT -A INPUT -s ! $DNS1 -d ! $IP -m udp -p udp -j LOG --log-level debug \
    --log-prefix "UDP PASSED: "
   
$IPT -A INPUT -s ! $DNS2 -d ! $IP -m udp -p udp -j LOG --log-level debug \
    --log-prefix "UDP PASSED: "
   
$IPT -A OUTPUT -d ! $DNS1 -s ! $IP -m udp -p udp -j LOG --log-level debug \
    --log-prefix "UDP PASSED: "

$IPT -A OUTPUT -d ! $DNS2 -s ! $IP -m udp -p udp -j LOG --log-level debug \
    --log-prefix "UDP PASSED: "
   

$IPT -A INPUT -m tcp -p tcp -m state --state NEW -j LOG --log-level debug \
    --log-prefix "NEW CONNECTION: "

#$IPT -N LOG_DROP
#$IPT -A LOG_DROP -j LOG --log-tcp-options --log-ip-options --log-prefix "[IPTABLES DROP] : "
#$IPT -A LOG_DROP -j DROP
#$IPT -A INPUT -j LOG_DROP   
#$IPT -A OUTPUT -m owner --uid-owner 1003 -m state --state NEW -p tcp -j LOG --log-level debug \
     --log-tcp-options --log-ip-options --log-prefix "[IRCD-BOT SPEAK]: "

# Check states, match and allow sane connections

$IPT -A INPUT -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -m state --state NEW -j DROP
$IPT -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT



## Allow UID 99 for HTTPD & UID 1003 for IRCD


$IPT -A INPUT -p tcp --dport 80 --sport 1024:65535 -m state --state NEW -j ACCEPT
$IPT -A INPUT -p tcp --dport 443 --sport 1024:65535 -m state --state NEW -j ACCEPT
$IPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 6667 -j ACCEPT
$IPT -A INPUT -p tcp -m state --state NEW -m tcp --dport 6697 -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 1003 -p tcp -j ACCEPT       
$IPT -A OUTPUT -m owner --uid-owner 99 -p tcp -j ACCEPT
$IPT -A OUTPUT -m owner --uid-owner 0 -p tcp -j ACCEPT
$IPT -A OUTPUT -m owner --uid-owner 1009 -p tcp -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 99 -d $DNS1 -p tcp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1003 -d $DNS1 -p tcp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 99 -d $DNS1 -p udp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1003 -d $DNS1 -p udp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 99 -d $DNS2 -p tcp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
       
$IPT -A OUTPUT -m owner --uid-owner 1003 -d $DNS2 -p tcp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
               
$IPT -A OUTPUT -m owner --uid-owner 99 -d $DNS2 -p udp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
                       
$IPT -A OUTPUT -m owner --uid-owner 1003 -d $DNS2 -p udp \
    --dport 53 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 1003 -p tcp \
    --dport 113 -d 0/0 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1003 -p udp \
    --dport 113 -d 0/0 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   


## Allow incoming/outgoing SMTP and root to do DNS queries

$IPT -A INPUT -p tcp --dport 25 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 0 -p tcp --sport 25 \
    -m state --state ESTABLISHED,RELATED -j ACCEPT
   

$IPT -A OUTPUT -o $INT -m owner --uid-owner 0 -d $DNS1 -p udp \
    --dport 53 --sport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 0 -d $DNS1 -p tcp \
    --dport 53 --sport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -o $INT -m owner --uid-owner 0 -d $DNS2 -p udp \
    --dport 53 --sport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
       
$IPT -A OUTPUT -m owner --uid-owner 0 -d $DNS2 -p tcp \
    --dport 53 --sport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 1005 -d $DNS2 -p udp \
    --dport 53 --sport 1024:65535 \
        -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT   
       
$IPT -A OUTPUT -m owner --uid-owner 1005 -d $DNS1 -p udp \
    --dport 53 --sport 1024:65535 \
        -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT


## Allow incoming Dovecot PoP server connections

$IPT -A INPUT -p tcp --dport 110 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A INPUT -p tcp --dport 995 --sport 1024:65535 -m state \
    --state NEW,ESTABLISHED,RELATED -j ACCEPT


## Allow users root, h4x0r3d and fwaggle to request DNS based on UID

$IPT -A OUTPUT -m owner --uid-owner 0 -p tcp --dport 53 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1003 -p tcp --dport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1005 -p tcp --dport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 0 -p udp --dport 53 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
   
$IPT -A OUTPUT -m owner --uid-owner 1003 -p udp --dport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

$IPT -A OUTPUT -m owner --uid-owner 1005 -p udp --dport 1024:65535 \
    -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

## Allow and rate-limit SSH and drop more than 2 connections/min and pass my ISP subnet thru

$IPT -A INPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT
$IPT -A INPUT -p tcp -s 9.8.0.0/255.0.0.0 --dport 22 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$IPT -A INPUT -p tcp -s 9.9.0.0/255.0.0.0 --dport 22 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
$IPT -I INPUT -i eth0 -p tcp --dport 22 -m state --state NEW -m recent --set
$IPT -I INPUT -i eth0 -p tcp --dport 22 -m state --state NEW -m recent \
    --update --seconds 60 --hitcount 2 -j DROP



## Allow my ISP subnet to access webmin and the BOINC client

$IPT -A INPUT -s 59.88.0.0/255.248.0.0 -p tcp -m state --state NEW -m tcp --dport 10000 -j ACCEPT
$IPT -A INPUT -s 59.96.0.0/255.252.0.0 -p tcp -m state --state NEW -m tcp --dport 10000 -j ACCEPT

$IPT -A INPUT -s 59.88.0.0/255.248.0.0 -p tcp -m state --state NEW -m tcp --dport 65500 -j ACCEPT
$IPT -A INPUT -s 59.96.0.0/255.252.0.0 -p tcp -m state --state NEW -m tcp --dport 65500 -j ACCEPT



## Allow and rate-limit ICMP echo and time exceeded requests

$IPT -A INPUT -j REJECT --reject-with icmp-port-unreachable
$IPT -A INPUT -p icmp --icmp-type 8 -m limit --limit 3/second -j ACCEPT
$IPT -A INPUT -p ICMP --icmp-type 11 -m limit --limit 2/second -j ACCEPT


##Deny using /etc/deny.hosts

    for host in `cat /etc/deny.hosts`; do
        $IPT -I INPUT -s $host -j DROP
        $IPT -I OUTPUT -d $host -j DROP
   
done