How can I configure firewall rules for minimal attack surface?
Asked on Oct 08, 2025
Answer
To configure firewall rules for a minimal attack surface, focus on allowing only necessary traffic and blocking everything else. This approach reduces potential entry points for attackers.
<!-- BEGIN COPY / PASTE -->
# Example firewall configuration using iptables
# Default policy to drop all incoming and forwarding traffic
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
# Allow incoming traffic on port 80 (HTTP) and 443 (HTTPS)
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
# Allow traffic from established connections
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
# Allow loopback interface traffic
iptables -A INPUT -i lo -j ACCEPT
<!-- END COPY / PASTE -->Additional Comment:
- Start with a default deny policy and explicitly allow only necessary services.
- Regularly review and update firewall rules to adapt to changing requirements.
- Use logging to monitor and analyze blocked traffic for potential threats.
✅ Answered with Security best practices.
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