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@asifiqbal
Forked from rbdcti/firewall.sh
Last active August 29, 2015 14:12
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# Drop ICMP echo-request messages sent to broadcast or multicast addresses
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
# Drop source routed packets
echo 0 > /proc/sys/net/ipv4/conf/all/accept_source_route
# Enable TCP SYN cookie protection from SYN floods
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
# Don't accept ICMP redirect messages
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects
# Don't send ICMP redirect messages
echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
# Enable source address spoofing protection
echo 1 > /proc/sys/net/ipv4/conf/all/rp_filter
# Log packets with impossible source addresses
echo 1 > /proc/sys/net/ipv4/conf/all/log_martians
# Flush all chains
/sbin/iptables --flush
# Allow unlimited traffic on the loopback interface
/sbin/iptables -A INPUT -i lo -j ACCEPT
/sbin/iptables -A OUTPUT -o lo -j ACCEPT
# Set default policies
/sbin/iptables --policy INPUT DROP
/sbin/iptables --policy OUTPUT DROP
/sbin/iptables --policy FORWARD DROP
# Previously initiated and accepted exchanges bypass rule checking
# Allow unlimited outbound traffic
/sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A OUTPUT -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#Ratelimit SSH for attack protection
/sbin/iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP
/sbin/iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set
/sbin/iptables -A INPUT -p tcp --dport 22 -m state --state NEW -j ACCEPT
# Allow certain other ports
/sbin/iptables -A INPUT -p tcp --dport 80 -m state --state NEW -j ACCEPT #HTTP
/sbin/iptables -A INPUT -p tcp --dport 443 -m state --state NEW -j ACCEPT #HTTPS
# Drop all other traffic
/sbin/iptables -A INPUT -j DROP
# Have these rules take effect when iptables is started
#/etc/init.d/iptables save
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