ASCII Tools

Visual Firewall Simulator

Build iptables rules and simulate how packets are filtered
Ruleset

INPUT

policy
#1-A INPUT -i lo -m comment --comment "allow loopback" -j ACCEPT

FORWARD

policy

No rules — every packet falls through to the DROP policy.

OUTPUT

policy

No rules — every packet falls through to the ACCEPT policy.

Add rule
Packet
Describe a packet, then simulate it against the ruleset above.
Simulation log

No simulations yet this session.

iptables commands
#!/usr/bin/env bash
# Generated by https://asciitools.com/firewall
set -euo pipefail

# Start from a clean filter table
iptables -F
iptables -X

# Default policies
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT

# INPUT
iptables -A INPUT -i lo -m comment --comment "allow loopback" -j ACCEPT