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Topic: Firewalls

O'Reilly Network articles about this topic:

Greylisting with PF (BSD DevCenter)
Greylisting--delaying mail delivery briefly per the SMTP RFCs--is an effective way to reduce the amount of incoming spam. While many greylisting solutions require customization of your SMTP server, OpenBSD's PF can do it too. Dan Langille shows how to use the powerful packet filter to identify and pass legitimate mail, delay and divert potential spammers, and throw in some OS fingerprinting to ward off certain zombie clients.

Sharing Internet Connections (BSD DevCenter)
Protecting your computer when you're online is good. If you have multiple computers in your home or small business, protecting all of them is also good--especially if you can share your internet connection. Dru Lavigne demonstrates how to allow other computers to use the network safely with a FreeBSD or similar Unix system and fwbuilder.

Using IPFW Rulesets with BSD Firewalls (BSD DevCenter)
The IPFW firewall comes with FreeBSD, but its documentation isn't entirely clear. Dennis Olvany demonstrates how to create and maintain IPFW rulesets to keep you secure but also to prevent network outages during updates.

Building a Desktop Firewall (BSD DevCenter)
By now, many internet users know that they need a firewall to protect their computers while they're online. Knowing that doesn't convey the knowledge of how to create and maintain a firewall. A nice GUI firewall builder called fwbuilder makes it possible to set up a working firewall in ten minutes--on Linux, *BSD, and Mac OS X. Dru Lavigne shows how it works on FreeBSD.

Network Filtering by Operating System (BSD DevCenter)
Some operating systems are better networking citizens than others. Depending on your network, you may want to prioritize traffic from certain machines over traffic from other operating systems--especially when the latest Windows worm strikes. Avleen Vig shows how to use pf, altq, and Squid on FreeBSD to shape your bandwidth with respect to the systems you run.

Building an OpenBSD Live CD (BSD DevCenter)
Linux isn't the only operating system that boots and runs off a CD. OpenBSD does as well. Kevin Lo uses his for didactic purposes, but this is a good example for taking your desktop or firewall along with you. Here's how to build and customize an OpenBSD installation on a CD.

Preventing Denial of Service Attacks (SysAdmin DevCenter)
If you have servers on the public Internet, you're likely vulnerable to external Denial of Service (DoS) attacks. (You may be vulnerable to accidental internal attacks, too.) Fortunately, you can limit their likelihood and severity. Avleen Vig discusses strategies for diagnosing and defending against DoS attacks.

OpenBSD PF Developer Interview, Part 2 (SysAdmin DevCenter)
With the release of OpenBSD 3.5, users and administrators gear up for new features. Federico Biancuzzi interviewed six leading OpenBSD developers responsible for PF, the powerful packet filter, on new features and goals. This is the second half of the interview.

OpenBSD PF Developer Interview (SysAdmin DevCenter)
On the eve of OpenBSD's 3.5 release, users and administrators gear up for new features. Federico Biancuzzi interviewed six leading OpenBSD developers responsible for PF, the powerful packet filter, on new features and goals.

Changes in pf: Packet Filtering (BSD DevCenter)
OpenBSD's packet filter has really grown up. Since its introduction in OpenBSD 3.0, it's become an advanced tool for networking and security. In the third of four articles, Jacek Artymiak explores new options for packet filtering with pf in OpenBSD 3.2, after NAT and redirection have taken place.

Changes in pf: More on NAT (BSD DevCenter)
OpenBSD's packet filter has really grown up. Since its introduction in OpenBSD 3.0, it has become an advanced tool for networking and security. In the second of four articles, Jacek Artymiak presents a sample NAT and DMZ ruleset that is easily customized.

NAT with pf (BSD DevCenter)
OpenBSD's packet filter has really grown up. Since its introduction in OpenBSD 3.0, it has become an advanced tool for networking and security. In the first of four articles, Jacek Artymiak examines recent updates to pf. This week, he looks at Network Address Translation.

Patching OpenBSD (BSD DevCenter)
The nice thing about software is that you can patch it to fix problems. The tricky thing about software is that you have to patch it to fix problems. Your systems are only as secure as your patching strategy allows. Jacek Artymiak explains how to apply patches to your OpenBSD machines.

Downloading Files from Behind the Firewall (BSD DevCenter)
Securing your network often means saying "no" to some user requests and "try this instead" to others. Instead of punching holes in your firewall, can you educate your users to use better tools? Jacek Artymiak describes effective downloading utilities, and strategies to promote them.

VPNs and IPSec Demystified (BSD DevCenter)
How do you allow remote users to access resources on your network securely over an insecure connection? With a VPN. Never fear, Dru Lavigne's latest Cryptosystems column explains the concepts and terminology behind the technology.

Cryptosystems: Configuring SSH (BSD DevCenter)
Cryptosystems are handy, but they're not for everyone right out of the box. In her second article on SSH, Dru Lavigne explores some of the more common configuration options for clients and servers.

Managing Advanced PF Logs (BSD DevCenter)
Jacek Artymaik shows us how to implement a Perl script that reads pf logs from the pflog fifo pipe, archives logs on the monitoring firewall, and sends them to another fifo pipe so that log analysis software can pick them up for analysis.

Securing Remote PF Firewall Logs (BSD DevCenter)
Jacek Artymiak shows us how to improve the security of remotely logged firewall logs and how to calculate how much storage space we need to keep a reasonable amount of logs for convenient analysis.

Archiving PF Firewall Logs (BSD DevCenter)
Jacek Artymiak tackles automating the transfer of logs from the firewall to one of the workstations connected to the internal private network segment.

Securing Small Networks with OpenBSD, Part 5 (BSD DevCenter)
On a busy network, your firewall logs could quickly fill up your hard drive or be deleted by log file rotations. Jacek Artymiak shows how not to let this happen.

Securing Small Networks with OpenBSD, Part 4 (BSD DevCenter)
Jacek Artymiak covers pf log file analysis.

Securing Small Networks With OpenBSD, Part 2 (BSD DevCenter)
OpenBSD switched from using IPFilter as its default firewall to PF, or Packet Filter, as the new default. Jacek Artymiak explains how to make a smooth transition from ipf to pf.

Securing Small Networks with OpenBSD, Part 1 (BSD DevCenter)
Small networks are often more vulnerable than large ones because they lack the money to implement good security. Artymiak Jacek explains how to secure a small network on a tight budget.

Monitoring IPFW Logs (BSD DevCenter)
Dru Lavigne shows us how to monitor ipfw logs and more importantly how to deal with what we find.

IPFW Logging (BSD DevCenter)
Firewalls can potentially block huge amounts of traffic. Dru Lavigne shows us how to fine-tune our firewall logs to reveal the traffic that concerns us most.

BSD Firewalls: Fine-Tuning Rulesets (BSD DevCenter)
Dru Lavigne helps us fine-tune our firewall rules. She uses DHCP as an example, steps through its requirements and shows how to implement the appropriate firewall rules.

BSD Firewalls: IPFW Rulesets (BSD DevCenter)
Dru Lavigne explains how to create IPFW firewall rules.

BSD Firewalls: IPFW (BSD DevCenter)
Building a firewall? Dru Lavigne gets you started with an IPFW firewall on FreeBSD.

BSD Firewalls: IPFW (BSD DevCenter)
Building a firewall? Dru Lavigne gets you started with an IPFW firewall on FreeBSD.

Scanning Your Network (BSD DevCenter)
Dru Lavigne shows us how to use nmap, a port scanning utility, to secure Unix servers and workstations.

Capturing TCP Packets (BSD DevCenter)
Want to capture network packets? Dru Lavigne shows how simple the process is and explains how to analyze the captured data.

TCP Protocol Layers Explained (BSD DevCenter)
Dru Lavigne explains how to read IP packet headers.

Java JDE Allows Unauthorized Commands (Linux DevCenter)
Noel Davis shows us a problem in Java that allows Java code to execute unauthorized commands; buffer overflows in CUPS and sudo; temporary file problems with StarOffice, MicroFocus COBOL, and CUPS; and vulnerabilities in pgp4pine, the Solaris LDAP PAM module, adcycle, and Zope.

Buffer-Overflow Problems in BIND (Linux DevCenter)
Buffer-overflow bugs are discovered in BIND, gnuserv, tinyProxy, and INN; developers report issues with ntop and LPRng.

PalmOS, Half-Life Server, and Ethereal Vulnerabilities (Linux DevCenter)
Problems this week include more symlink problems with catman and dialog, buffer overflows in oops, halflifeserver, and ethereal, key problems with gnupg, problems with PalmOS devices, and a prime example of amazing vulnerabilities in third-party software packages.

Security Alerts: SAMBA, pine, ircd, and More (Linux DevCenter)
Noel Davis summarizes recent open source and Unix security-related advisories. Problems this week include symlink problems with joe, pico, and samba, a buffer overflow in bftpd, and problems with pine.

Security Alerts: Twig, Midnight Commander, and More (Linux DevCenter)
Noel Davis summarizes published open source and Unix exploits. Problems this week include arbitrary code execution in Twig, new symlink attacks, a hidden control code attack on Midnight Commander, and a LANGUAGE attack on glibc.

Security Alerts: Koules Local Root Exploit And More. (Linux DevCenter)
This week's exploits include a local root compromise in Koules 1.4, a buffer overflow in modutilities, and various problems with Alladin Ghostscript.

Security Alerts: OpenBSD Non-exploit and More (Linux DevCenter)
Noel Davis reviews the published exploits from Unix and open source. This week's Insecurities column includes a satirical non-exploit against OpenBSD

Setting Up a Firewall Under OpenBSD (BSD DevCenter)
A tutorial on the basic components that make up a firewall and how to set them up.


Other documents about this topic:

Below are other references available on the web for this topic. Since other sites may change their links, please if you find any that may need to be updated.

Building an ATM Firewall
[Source: Daemon News]



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