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Firewall

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OSF - Passive OS Fingerprinting For IPtables

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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.

Firewalk - Firewall Ruleset Testing Tool

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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?

Simplify System Security With the Uncomplicated Firewall

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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?

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

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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?

Set up Your Firewall With Firewall Builder

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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.

Gibraltar Firewall 2.6 Launched

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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.

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