[Level 3] Firewall in Ubuntu.
install gui tool for ufw # apt-get -y install gufw # gufw use command(ufw) to setting firewall, and the config file in in /lib/ufw/user.rules # ufw deny from any to any port 22 # ls -al /lib/ufw/user.rules -rw-r----- 1 root root 1405 2011-04-01 17:36 /lib/ufw/user.rules # ufw delete deny from any to any port 22 # ls -al /lib/ufw/user.rules -rw-r----- 1 root root 1263 2011-04-01 17:36 /lib/ufw/user.rules my setting history (reference only): ufw disable ufw default deny ufw logging ON ufw enable ufw allow 22/tcp ufw allow proto tcp from 192.168.1.0/24 to 192.168.1.101 port 80 use iptables command: #!/bin/bash MY_IP=192.168.100.101 # Flushing all rules and chains iptables -F iptables -X # Setting default policy iptables -P INPUT DROP iptables -P OUTPUT ACCEPT iptables -P FORWARD DROP # Allow traffic on loopback iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT # Allow ssh for in/out iptables -A INPUT -p tcp -s 0/0 -d $MY_IP --sport 513:65535 --dport 22 -m state...