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iptables rules for desktop computers

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Today I will show you the iptables rules I set on my main personal computer, with detailed comments about why I came to use these rules after several years of Linux desktop usage. The rules I use now have been simplified as much as I could and are based on common rules and advice that can be found on the network and also on input I got from experienced network administrators. I

Anthony Pell
Apr 06, 2010

Flint

Flint examines firewalls, quickly computes the effect of all the configuration rules, and then spots problems so you can: CLEAN UP RUSTY CONFIGURATIONS that are crudded up with rules that can

Anthony Pell
Mar 26, 2010

Port Knocking

Fred Stluka from Bristle.com just introduced me to port knocking -- a method of opening ports on a firewall by trying to connect with a series of ports in a pre-determined order. The sequence of "knocks" acts like a secret access code -- like tapping out the first couple of bars from your favorite song to tell someone inside that it's you.

Anthony Pell
Mar 03, 2010

Iptables Limits Connections Per IP

ow do I restrict the number of connections used by a single IP address to my server for port 80 and 25 using iptables? You need to use the connlimit modules which allows you to restrict the number of parallel TCP connections to a server per client IP address (or address block). This is useful to protect your server or vps box against flooding, spamming or content scraping.

Anthony Pell
Feb 11, 2010

Hacker pierces hardware firewalls with web page

On Tuesday, hacker Samy Kamkar demonstrated a way to identify a browser's geographical location by exploiting weaknesses in many WiFi routers. Now, he's back with a simple method to penetrate hardware firewalls using little more than some javascript embedded in a webpage.

Anthony Pell
Jan 07, 2010

DIY pfSense firewall system beats others for features, reliability, and security

With the prevalence of

Anthony Pell
Dec 07, 2009

Hitting a Wall: the Great UTM Challenge

In the beginning was the firewall, and it was pretty good. A big box of rules that sat between your network and the evils of the Internet, the firewall examined ports and protocols to decide which packets got in and which were barred at the door. Then things got, as things often do, complicated. New threats came sneaking in on trusted protocols, ports and protocols became tangled, and looking inside packets became just as important as noting their source, destination, and type.

Anthony Pell
May 27, 2009

5 Best Linux/BSD Firewall Tools

Over the course of recent years, some people have found the quality of most out-of-the-store firewall appliances either lacking functionality or worse, set at a price that has made them generally out of reach. Because of this issue, I thought it would be beneficial to write an article to better highlight what works and what does not with regard to turning an older PC into a standalone router/firewall appliance. What do you think about this list of firewall tools? Did they miss anyones that should be on it?

Bill Keys
Dec 19, 2008

OSF - Passive OS Fingerprinting For IPtables

Passive OS fingerprinting netfilter module allows to passively detect remote OS and perform various netfilter actions based on that knowledge. This module compares some data (WS, MSS, options and it's order, ttl, df and others) from packets with SYN bit set with dynamically loaded OS fingerprints. Starting from 2008_07_01 version OSF works only with Xtables, so you have to upgrade to recent kernels (and ename xtables support) and iptables (tested with 1.4.1.1). Also note, that Debian (starting from Lenny) has serious problems with iptables-dev package, which does not contain needed headers, so better install iptables from sources. Have you ever hear about a netfilter module that does passive OS fingerprinting? If you are interested in learning more about this check out this article.

Bill Keys
Dec 09, 2008

SmoothWall Simplifies Open Source Security

But Astaro is certainly not the only game in town

Brittany Day
Oct 24, 2008

Firewalk - Firewall Ruleset Testing Tool

Firewalk is an active reconnaissance network security tool that attempts to determine what layer 4 protocols a given IP forwarding device will pass. Firewalk works by sending out TCP or UDP packets with a TTL one greater than the targeted gateway. If the gateway allows the traffic, it will forward the packets to the next hop where they will expire and elicit an ICMP_TIME_EXCEEDED message. If the gateway hostdoes not allow the traffic, it will likely drop the packets on the floor and we will see no response. Do you need to test your firewall? This article look at the firewall rulset testing tool called Firwalk. Test it how and let us know what you think?

Bill Keys
Oct 16, 2008

Simplify System Security With the Uncomplicated Firewall

The Uncomplicated Firewall (UFW) is a new tool from Ubuntu whose goal is to make configuration of the built-in Linux packet filter less complicated and more secure for novice users. You must run UFW commands as root, so in Ubuntu, you must preface them with the sudo command. With UFW, enabling and disabling packet filtering is a simple matter of issuing the sudo ufw enable and sudo ufw disable commands. You set the default policy for filtering packets by running the sudo ufw default command and passing the allow or deny argument, depending on what you want to achieve. If you issue the sudo ufw default allow command, all incoming packets will be allowed by default, creating a very unsecure packet filter but giving you the broadest range of allowed services. Have you tested the new Firewall tool from Ubuntu that says that it makes packet filtering easier? There are tons of GUI firewall tools who's goal is to make it easy for novice users. So my question is why do we need another one?

Bill Keys
Oct 02, 2008

Devil-Linux Bundles Router/Firewall and Server in One Live CD

Devil-Linux might sound hellish for a Linux distribution, but this live CD offers many blessings for your server needs. Originally developed as a router/firewall distribution, Devil-Linux has expanded its functionality to include nearly every service that a server might offer. It can function as an LDAP server, a VPN server, an email or file server, and more. As stated in the documentation, Devil-Linux runs directly from a CD or DVD-ROM only, so you don't need to install anything to a hard disk -- just keep the Devil-Linux configuration files that automate the configuration upon reboot on a diskette or USB drive. Since access to the live CD is read-only, it's impossible to install rootkits or other malicious software to the distribution. Setting up a home firewall can be a great way to protect your network. This article looks at one Linux distro that is designed to be used as a firewall. What do you Devil-Linux for your home network's firewall?

Bill Keys
Sep 29, 2008

Set up Your Firewall With Firewall Builder

Firewall Builder (fwbuilder) is a graphical application that can help you to configure IP traffic filtering. It can compile the filtering policy you define into many specifications, including iptables and various languages used by Cisco and Linksys routers. Separating the actual policy you define and the implementation in this way should let you change what hardware is running your firewall without having to redefine your policy for that platform. How do you setup your firewall? Do you use an application to help or do you us just write your own Iptables? This article looks at a firewall application called fwbuilder and shows you some of the features of this software.

Bill Keys
Aug 14, 2008

Gibraltar Firewall 2.6 Launched

Gibraltar Firewall 2.6, a Linux firewall distribution based on Debian, was launched yesterday as announced by Rene Mayrhofer. This will be the last release that will use the Linux kernel 2.4, as the next Gibraltar editions will use the 2.6 kernel. Among other things, this edition of Gibraltar offers improved traffic shaping performance (the iptables marking rules were re-ordered and the pre-defined traffic classes were improved), and allows SSL Explorer plugins to be installed. Have you ever used the Gibraltar Firewall? Gibraltar provides the user with a web interface for setting up their firewall. Now it's available for the Linux 2.6 kernel. Also in this release they added full WLAN access point functionality.

Bill Keys
Jul 21, 2008

How To Set Up Shorewall (Shoreline) 4.0 Firewall On CentOS 5.1

The Shoreline Firewall, more commonly known as "Shorewall", is a high-level tool for configuring Netfilter. You describe your firewall/gateway requirements using entries in a set of configuration files. Shorewall reads those configuration files and with the help of the iptables utility, Shorewall configures Netfilter to match your requirements. Shorewall can be used on a dedicated firewall system, a multi-function gateway/router/server or on a standalone GNU/Linux system. Shorewall does not use Netfilter's ipchains compatibility mode and can thus take advantage of Netfilter's connection state tracking capabilities. https://shorewall.org/ Shorewall is a great firewall package for Linux it's, most distro's have packages available. What do you think about Shorewall? Do you have any other favorite firewall package.

Bill Keys
Jul 10, 2008

A Dedicated Firewall/Router: Devil-Linux

Devil-Linux is a distribution which boots and runs completely from CD. The configuration can be saved to a floppy diskette or a USB pen drive. It was originally intended to be a dedicated firewall/router but now Devil-Linux can also be used as a server for many applications. Attaching an optional hard drive is easy, and many network services are included in the distribution. Have you used any Linux distributions which are design to be used as a firewall or router? This article looks at the Devil-Linux distribution with some useful links to learn more about this Linux distro.

Bill Keys
May 20, 2008

Firewall Configurations With Guarddog

The KDE Guarddog program promises an easy Linux firewall setup with just a few clicks. Guarddog helps inexperienced users secure computers

Bill Keys
Apr 11, 2008

Linux Demilitarized Zone (DMZ) Ethernet Interface Requirements and Configuration

(The)Demilitarized zone, used to secure an internal network from external access. You can use Linux firewall to create DMZ easily. There are many different ways to design a network with a DMZ. The basic method is to use a single Linux firewall with 3 Ethernet cards. The following simple example discusses DMZ setup and forwarding public traffic to internal servers. There's a little advanced know-how required here and he recommends a couple good firewalls to set up such functionality just in case this very useful guide doesn't fit the bill. If you are looking to set up a Linux Demilitarized zone a couple of options include EnGarde, IpCop and others.

Brittany Day
Dec 17, 2007

Iptables as a Replacement for Commercial Enterprise Firewalls

Are you administrating a corporate network? How do you ensure securing your web services? There are many different solutions, but Iptables is one of the newer ones, and is up to the job. With IT budgets getting tighter, managers need to trim costs. Service contracts are expensive for any technology; firewalls are no exception. Netfilter, the project that provides the packet filtering program Iptables, is a free firewall alternative. While it lacks the service contract of commercial solutions and a pretty interfaces to make firewall modification easy, it has solid performance, performs effectively at firewalling, and allows for add-on functionality to enhance its reporting and response functions.

Brittany Day
Dec 14, 2007

Firewall - Page 2.75

An Introduction to UFW, Ubuntu’s ‘Uncomplicated’ Firewall

The Open Source Firewall – IPFire 2.27 – Core Update 173 Released: What’s New?

IPFire Hardened Linux Firewall Distro Is Now Powered by Linux Kernel 6.1 LTS