iptables -
*filter # Allows all loopback (lo0) traffic and drop all traffic to 127/8 that doesn't use lo0 -A INPUT -i lo -j ACCEPT -A INPUT ! -i lo -d 127.0.0.0/8 -j REJECT # Accepts all established inbound connections -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT # Allows all outbound traffic # You could modify this to only allow certain traffic -A OUTPUT -j ACCEPT # Allows HTTP and HTTPS connections from anywhere (the normal ports for websites) -A INPUT -p tcp --dport 80 -j ACCEPT -A INPUT -p tcp --dport 443 -j ACCEPT # Allows SSH connections # The --dport number is the same as in /etc/ssh/sshd_config -A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT # Now you should read up on iptables rules and consider whether ssh access # for everyone is really desired. Most likely you will only allow access from certain IPs. # Allow ping # note that blocking other types of icmp packets is considered a bad idea by some # remove -m icmp --icmp-type 8 from this line to allow all kinds of icmp: # https://security.stackexchange.com/questions/22711 -A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT # log iptables denied calls (access via 'dmesg' command) -A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7 # Reject all other inbound - default deny unless explicitly allowed policy: -A INPUT -j REJECT -A FORWARD -j REJECT