iptables

Configure firewall rules.

$ iptables

Command mode

List rules

Append rule

Delete rule

Flush rules

Set policy

Table

filter

nat

mangle

raw

security

Chain

INPUT

OUTPUT

FORWARD

Verbose (-v)Numeric output (-n)Show line numbers (--line-numbers)

Examples

# List rules in filter table
iptables -t filter -L -n --line-numbers

# Allow SSH on port 22
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

# Block traffic from a subnet
iptables -A INPUT -s 10.0.0.0/8 -j DROP

# Set default policy to DROP
iptables -P INPUT DROP

# Delete rule 3 from INPUT chain
iptables -D INPUT 3

# Flush all rules
iptables -F