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Port Knocking
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03 March 2010
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Source: IT World - Posted by anthony
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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. |
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Source: cyberciti - Posted by anthony
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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. |
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Source: The Register - Posted by anthony
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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. |
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Source: Tech Republic - Posted by anthony
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With the prevalence of “black box” appliance firewalls available for $50 or less, one might wonder why you would look for a do-it-yourself solution. Linksys and D-Link, among other vendors, create simple and easy to configure firewall solutions for cheap. And let’s face it, a firewall isn’t something you can choose to use anymore; a firewall is your first line of defense, and a critical one at that. |
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Source: CIO / InfoWorld - Posted by anthony
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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. |
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Source: IntranetJournal - Posted by Bill Keys
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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? |
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Source: ioremap.net - Posted by Bill Keys
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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. |
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Source: enterprise networking planet - Posted by John P. Forman
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But Astaro is certainly not the only game in town — another well known name in this market is SmoothWall Ltd, a UK based company which maintains an open source firewall project also called SmoothWall. This software has been evolving for the last eight years, the current version being called SmoothWall Express 3.0
The latest open source firewall appliance from UK company SmoothWall includes load balancing, web filtering, and can also act as a VPN gateway. Check it out in this informative article. |
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Source: DarkNet - Posted by Bill Keys
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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? |
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Source: Linux.com - Posted by Bill Keys
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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? |
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