Set Up a Firewall on Linux (UFW & IPTables) | FastLayer
A firewall is an essential part of any server configuration. It controls network access and protects your server from unauthorized access. In this guide, we'll show you how to set up a secure firewall using UFW or IPTables on Debian/Ubuntu (and partly CentOS/Fedora) — specifically for FastLayer servers.
✅ Requirements
- Root access or use of
sudo - Debian/Ubuntu, or alternatively CentOS/RHEL with UFW support
- SSH access configured
⚡ Step 1: Gain Root Privileges
sudo su -Step 2: Install UFW
Debian/Ubuntu:
sudo apt update
sudo apt install ufwCentOS/Fedora/RHEL:
sudo dnf install ufw
# or for older versions
sudo yum install ufwStep 3: Whitelist SSH Port
If you changed the SSH port, edit the OpenSSH profile file:
nano /etc/ufw/applications.d/openssh-serverExample:
[OpenSSH]
title=Secure shell server
description=OpenSSH implementation
ports=2222/tcpThen:
ufw app update OpenSSH
ufw app info OpenSSHStep 4: Enable UFW and Allow Ports
ufw allow OpenSSH
ufw allow 5555
ufw enableCheck with:
ufw status
ufw status verbose
ufw status numbered❌ Step 5: Delete Rules
By number:
ufw delete 2Directly:
ufw delete allow 5555⚖️ Step 6: Allow or Block Specific IPs
Allow:
ufw allow from 10.1.2.3
ufw allow from 10.1.0.0/24 to any port 4444Block:
ufw deny from 10.3.2.5
ufw deny from 10.3.2.4 to any port 3333Block outgoing connections:
ufw deny out 25
ufw deny out to 10.4.4.4Alternative: Use IPTables Directly
Basic rules:
iptables -I INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -I INPUT -p icmp -j ACCEPT
iptables -I INPUT -i lo -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPTIPv6:
ip6tables -A INPUT -p tcp --dport 22 -j ACCEPTBlock:
iptables -A INPUT -p tcp --dport 3333 -j DROP
iptables -A INPUT -s 10.4.5.6 -j DROPAllow:
iptables -I INPUT -s 10.1.2.3 -j ACCEPT
iptables -I INPUT -s 10.4.0.0/24 -p tcp -m multiport --dports 2222,3333 -j ACCEPTSave IPTables Permanently (Debian/Ubuntu)
apt install netfilter-persistent
iptables-save > /etc/iptables/rules.v4
ip6tables-save > /etc/iptables/rules.v6
systemctl enable netfilter-persistent
systemctl restart netfilter-persistentCheck after reboot:
sudo reboot
iptables-save
ip6tables-saveFastLayer
Our servers come without a pre-installed firewall, giving you full control. With this guide, you can set up your own secure environment in just a few minutes.
More Linux tutorials + hosting: https://fastlayer.eu
