Articles taggués ‘iptables ipv4’

Basic iptables Rulesets for IPv4 and IPv6

15/10/2015 Comments off

iptables ipv4Appropriate firewall rules heavily depend on the services being run. Below are iptables rulesets to secure your Linode if you’re running a web server. These are given as an example! A real production web server may want or require more or less configuration and these rules would not be appropriate for a file or database server, Minecraft or VPN server, etc.

iptables rules can always be modified or reset later, but these basic rulesets serve only as a beginning demonstration.



# Allow all loopback (lo0) traffic and reject traffic
# to localhost that does not originate from lo0.
-A INPUT -i lo -j ACCEPT
-A INPUT ! -i lo -s -j REJECT

# Allow ping and traceroute.
-A INPUT -p icmp --icmp-type 3 -j ACCEPT
-A INPUT -p icmp --icmp-type 8 -j ACCEPT
-A INPUT -p icmp --icmp-type 11 -j ACCEPT

# Allow SSH connections.
-A INPUT -p tcp -m state --state NEW --dport 22 -j ACCEPT

# Allow HTTP and HTTPS connections from anywhere
# (the normal ports for web servers).
-A INPUT -p tcp --dport 80 -j ACCEPT
-A INPUT -p tcp --dport 443 -j ACCEPT

# Accept inbound traffic from established connections.

# Log what was incoming but denied (optional but useful).
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables_INPUT_denied: " --log-level 7

# Reject all other inbound.

# Log any traffic which was sent to you
# for forwarding (optional but useful).
-A FORWARD -m limit --limit 5/min -j LOG --log-prefix "iptables_FORWARD_denied: " --log-level 7

# Reject all traffic forwarding.


Optional: If you plan to use Linode Longview, add this additional rule below the section for allowing HTTP and HTTPS connections:
# Allow incoming Longview connections 
-A INPUT -s -m state --state NEW -j ACCEPT


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