Tag: Firewall

Anti SYN Flood with IPTables

#!/bin/sh # A simple shell to build a Firewall anti SYN Flood # Under CentOS, Fedora and RHEL / Redhat Enterprise Linux # servers. # —————————————————————————- # Written by LongVNIT # (c) 2009 lifeLinux under GNU GPL v2.0+ IPT=”iptables” MODPROBE=”modprobe” IF=”eth0″ IP=”″ PORT=”22 80 443″ CHECK_TIME=60 BAN_TIME=120 HITCOUNT=10 MOD=”ip_tables ip_conntrack […]

Detecting DoS / DDoS Attack on a Windows 2003 / 2008 Server

Question: How do I detect a DDOS (Distributed denial of service) / DOS attack on a Windows Server 2003 / 2000 / 2008? Can I use Linux netstat command syntax to detect DDoS attacks? Answer:A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource […]

Linux: Block Port With IPtables

How do I block port number with iptables under Linux operating systems? Port numbers which are recognized by Internet and other network protocols, enabling the computer to interact with others. Each Linux server has a port number (see /etc/services file). For example: TCP port 80 – HTTP Server TCP port […]

How to Block Ftp Access/Port using iptables OR CSF?

The default firewall that comes along with Linux is “iptables” and you can use iptables to block Ftp access/port on your server. Completely block Ftp access on the server: # iptables -A INPUT -p tcp –dport 21 -j DROP Block Ftp access for a specific IP address, say # […]

VPS iptables rule limit is too low.

You may come across with a “numiptent” error message while restarting iptables or whatever firewall (say csf) you have installed on your VPS. The error appear as follows: The VPS iptables rule limit (numiptent) is too low (200/250) – stopping firewall to prevent iptables blocking all connections There is a […]

HowTo: Add iptable modules on a VPS

If you receive the following error on restating iptables on a VPS: error message: from firewall software ~ iptables: Unknown error 4294967295 you need to make sure the required iptable modules are loaded in the host server kernel. You have to use modprobe to load the following modules in the […]

Howto: Change the FTP port to a non-standard port?

If you are looking to change the Ftp port on your server from 21 to a non-standard port say 2121, you need tweak the ‘bind’ option in the Ftp configuration file.  On a cPanel server with pure-ftp as a Ftp server, you need to edit the pure-ftpd.conf file # pico […]

The Perfect Linux Firewall Part II — IPCop & Copfilter

This document is the second segment in a series on installing IPCop firewall. We will be creating a “DMZ” for hosting your own web server or mail server and the Copfilter proxy for filtering your application layer ingress and egress network traffic. This is intended to be a rough overview […]

The Perfect Linux Firewall Part I — IPCop

The Perfect Linux Firewall Part I — IPCop Version 2.3 Author: Joseph Guarino Last edited 02/22/2006 This document describes how to install the GNU/Linux GPL IPCop firewall and create a small home office network. In the second installment we cover creating a DMZ for hosting your own web server or […]