Security

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HowTo: Install And Configure FWKNOP (Using EnGarde Linux)

HowTo: Install And Configure FWKNOP (Using EnGarde Linux)

Secret knocks have been used for purposes as simple and childish as identifying friend or foe during a schoolyard fort war. Fraternities teach these knocks as a rite of passage into their society, and in our security world we can implement this layer of security to lock down an SSH server. The FireWall KNock Operator (fwknop) is an excellent port knocking implementation that combines encrypted port knocking with passive OS finger-printing. This makes it possible to define specifically which Linux systems are allowed access to your SSH server. fwknop combines its functionality with iptables rules and log messages to grant or deny access to the SSH daemon.

Virtual Users And Domains With Postfix, Courier And MySQL (CentOS 5.1)

Virtual Users And Domains With Postfix, Courier And MySQL (CentOS 5.1)

This document describes how to install a Postfix mail server that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses. The resulting Postfix server is capable of SMTP-AUTH and TLS and quota (quota is not built into Postfix by default, I'll show how to patch your Postfix appropriately). Passwords are stored in encrypted form in the database (most documents I found were dealing with plain text passwords which is a security risk). In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses.

Configuring SSH To Use Freeradius And WiKID For Two-Factor Authentication

Configuring SSH To Use Freeradius And WiKID For Two-Factor Authentication

Radius is a great standard. It is powerful enough to accomplish a great deal and simple enough to be easy to handle. Freeradius is an excellent, open source radius server that ships with many Linux variants. It is well documented and well supported. The WiKID Strong Authentication server is a commercial/open source two-factor authentication system that uses public key encryption to transmit PINs and one-time passcodes securely to software tokens running on Blackberries, cell phones, Palms, PocketPCs or, using the J2SE client, Linux, Macs and Windows PCs. You can think of WiKID like certificates, but without the hassles of white lists/black lists and more secure - because the PIN is validated on the server preventing offline brute-force attacks.

Virtual Users And Domains With Postfix, Courier And MySQL (Ubuntu 7.10)

Virtual Users And Domains With Postfix, Courier And MySQL (Ubuntu 7.10)

This document describes how to install a mail server based on Postfix that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses. The resulting Postfix server is capable of SMTP-AUTH and TLS and quota (quota is not built into Postfix by default, I'll show how to patch your Postfix appropriately). Passwords are stored in encrypted form in the database (most documents I found were dealing with plain text passwords which is a security risk). In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses.

Adding And Updating SpamAssassin Rulesets With RulesDuJour

Adding And Updating SpamAssassin Rulesets With RulesDuJour

This article explains how you can download additional SpamAssassin rulesets resp. automatically update these rulesets with a shell script called RulesDuJour. These additional rulesets can increase your spam recognition rate dramatically. Most of the rulesets that RulesDuJour supports can be found on the SA Rules Emporium web site.

Intrusion Detection: Snort, Base, MySQL, And Apache2 On Ubuntu 7.10 (Gutsy Gibbon)

Intrusion Detection: Snort, Base, MySQL, and Apache2 On Ubuntu 7.10 (Gutsy Gibbon)

In this tutorial I will describe how to install and configure Snort (an intrusion detection system (IDS)) from source, BASE (Basic Analysis and Security Engine), MySQL, and Apache2 on Ubuntu 7.10 (Gutsy Gibbon). Snort will assist you in monitoring your network and alert you about possible threats. Snort will output its log files to a MySQL database which BASE will use to display a graphical interface in a web browser.

Virtual Users And Domains With Postfix, Courier And MySQL (Fedora 8)

Virtual Users And Domains With Postfix, Courier And MySQL (Fedora 8)

This document describes how to install a mail server based on Postfix that is based on virtual users and domains, i.e. users and domains that are in a MySQL database. I'll also demonstrate the installation and configuration of Courier (Courier-POP3, Courier-IMAP), so that Courier can authenticate against the same MySQL database Postfix uses. The resulting Postfix server is capable of SMTP-AUTH and TLS and quota (quota is not built into Postfix by default, I'll show how to patch your Postfix appropriately). Passwords are stored in encrypted form in the database (most documents I found were dealing with plain text passwords which is a security risk). In addition to that, this tutorial covers the installation of Amavisd, SpamAssassin and ClamAV so that emails will be scanned for spam and viruses.

Full Mail Server Solution w/ Virtual Domains & Users (Debian Etch, Postfix, Mysql, Dovecot, DSpam, ClamAV, Postgrey, RBL)

Full Mail Server Solution w/ Virtual Domains & Users (Debian Etch, Postfix, MySQL, DoveCot, DSpam, ClamAV, Postgrey, RBL)

This guide describes how to set up a full email solution in Debian Linux (all code is from Debian Etch).  I was asked to design a secure, scalable, portable solution for a small company.  While the guide references many 'servers', the company only had 4 physical machines, Xen was used to virtualize the entire solution.  That particular aspect of the system is not discussed in this guide, although I will try to get it into the next revision.

Chrooted SSH/SFTP On Fedora 7

Chrooted SSH/SFTP On Fedora 7

This document describes how to set up a chrooted SSH/SFTP environment on Fedora 7. The chrooted users will be jailed in a specific directory where they can't break out. They will be able to access their jail via SSH and SFTP.

Preventing Brute Force Attacks With Fail2ban On OpenSUSE 10.3

Preventing Brute Force Attacks With Fail2ban On OpenSUSE 10.3

In this article I will show how to install and configure fail2ban on an OpenSUSE 10.3 system. Fail2ban is a tool that observes login attempts to various services, e.g. SSH, FTP, SMTP, Apache, etc., and if it finds failed login attempts again and again from the same IP address or host, fail2ban stops further login attempts from that IP address/host by blocking it with an iptables firewall rule.

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