Introduction

Security of network infrastructure is of utmost importance for enterprises of every scale. The MikroTik Firewall becomes the layer-three choice due to the advanced configuration possibilities, low pricing, and high performance. With a powerful firewall capability in MikroTik RouterOS, simple security scenarios as well as very complex ones can be configured. We will explain all details of installation, rule writing, configuration, and performance optimization of the MikroTik firewall in this paper.

1. What is MikroTik Firewall?

MikroTik Firewall is a packet filtering system based on the Router OS. It allows writing fairly advanced rules for incoming, outgoing, and routed traffic. Its main functions are as follows:

IP filtering

NAT (Network Address Translation)

Mangle

Raw

Connection tracking

2. MikroTik Device Setup (Basic Preparation)

Router does possess RouterOS

Winbox or WebFig access

At least 2 ethernet ports (for LAN/WAN separation)

You can access the router using Winbox with either the MAC address or IP.

3. Basic NAT and IP Setup

WAN and LAN interfaces:

/ip address add address=192.168.88.1/24 interface=ether2
/ip address add address=1.2.3.4/24 interface=ether1
NAT configuration (for Internet sharing):

/ip firewall nat add chain=srcnat out-interface=ether1 action=masquerade
4. How to Write MikroTik Firewall Rules?

MikroTik firewall rules are divided into three basic chains:

Input: Controls traffic coming to the Router

Forward: Controls traffic passing from LAN to WAN or vice versa

Output: Controls the traffic going out from the Router

Example of blocking ICMP (ping):

/ip firewall filter add chain=input protocol=icmp action=drop comment="Ping engelle"
Example of blocking traffic from a specific IP:

/ip firewall filter add chain=input src-address=203.0.113.5 action=drop comment="IP engelle"
5. Protection Against DDoS and Other Attacks

Connection limit:

/ip firewall filter add chain=forward connection-limit=100,32 protocol=tcp action=drop comment="Aşırı bağlantı engeller"
SYN Flood protection:

/ip firewall filter add chain=input protocol=tcp tcp-flags=syn connection-limit=30,32 action=drop comment="SYN flood"
6. MikroTik Firewall Performance Optimization

Take care of rule order: The most matching rules should be at the top.

Raw table usage: Faster rejection of unwanted connections.

Disable connection tracking, if unnecessary.

Add comments: Describe each rule for easy management.

7. Backup and Restore

All of your settings, including your firewall rules, can be backed up simply by exporting them:

/export file=backup
Restoring:

/import file=backup.rsc
Conclusion

MikroTik Firewall is a strong tool for the home consumer and enterprise network manager. Once set up correctly, it would usually guard the network from external threats, keeping it running at high performance. The examples in this article and optimization recommendations would go a long way.