Linux / FreeBSD: PDFCrack A Command Line Password Recovery Tool For PDF Files

Posted on in Categories FreeBSD, Linux, Linux desktop, Security last updated June 6, 2012

I already written about howto remove a password from all PDF files under Ubuntu or any other Linux distribution in a batch mode. However, many user want a simple command to recover password from pdf files. This is useful if you forgotten your password for pdf file. It is also useful for data-archaeologists, computer forensics professionals, people who want to test their password-strength (pdf files generated by webpass) and many more.

30 Best Sources For Linux / *BSD / Unix Documentation On the Web

Posted on in Categories Debian Linux, FreeBSD, HP-UX, Linux, Linux distribution, OpenBSD, RedHat/Fedora Linux, Ubuntu Linux, UNIX last updated December 21, 2011

Man pages are written by sys-admin and developers for IT techs, and are intended more as a reference than as a how to. Man pages are very useful for people who are already familiar with Linux, Unix, and BSD operating systems. Use man pages when you just need to know the syntax for particular commands or configuration file, but they are not helpful for new Linux users. Man pages are not good for learning something new for the first time. Here are thirty best documentation sites on the web for learning Linux and Unix like operating systems.

FreeBSD 8.0 Review: Enterprise Ready Server Operating System

Posted on in Categories FreeBSD, News, Sys admin last updated November 26, 2009

The FreeBSD Project is one of the oldest and successful project. FreeBSD is well known for its reliability, robustness, and performance.

A new version of the FreeBSD 8 is scheduled for release this week. A RC3 was made available for download few weeks ago for final round of testing before the official launch. nixCraft takes you for an in-depth look at the new features and major architectural changes in FreeBSD v8.0.

BIND 9 Dynamic Update DoS Security Update

Posted on in Categories BIND Dns, CentOS, Debian Linux, fedora linux, FreeBSD, Howto, Linux, Networking, package management, RedHat/Fedora Linux, Security, Solaris, Suse Linux, Sys admin, UNIX, Windows server last updated July 29, 2009

BIND 9 is an implementation of the Domain Name System (DNS) protocols. named daemon is an Internet Domain Name Server for UNIX like operating systems. Dynamic update messages may be used to update records in a master zone on a nameserver. When named receives a specially crafted dynamic update message an internal assertion check is triggered which causes named to exit. An attacker which can send DNS requests to a nameserver can cause it to exit, thus creating a Denial of Service situation. configuring named to ignore dynamic updates is NOT sufficient to protect it from this vulnerability. This exploit is public. Please upgrade immediately.

Top 20 OpenSSH Server Best Security Practices

Posted on in Categories CentOS, Debian Linux, fedora linux, FreeBSD, Gentoo Linux, Howto, Linux, Networking, package management, RedHat/Fedora Linux, Security, Suse Linux, Sys admin, Tips, Ubuntu Linux, UNIX last updated July 24, 2009
Don't tell anyone that I'm free

OpenSSH is the implementation of the SSH protocol. OpenSSH is recommended for remote login, making backups, remote file transfer via scp or sftp, and much more. SSH is perfect to keep confidentiality and integrity for data exchanged between two networks and systems. However, the main advantage is server authentication, through the use of public key cryptography. From time to time there are rumors about OpenSSH zero day exploit. Here are a few things you need to tweak in order to improve OpenSSH server security.

Lighttpd Traffic Shaping: Throttle Connections Per Single IP (Rate Limit)

Posted on in Categories Apache, CentOS, fedora linux, FreeBSD, Howto, Iptables, lighttpd, Linux, Networking, PF Firewall, RedHat/Fedora Linux, Security, Ubuntu Linux, UNIX last updated June 21, 2009

If you do not control or throttle end users, your server may run out of resources. Spammers, abuser and badly written bots can eat up all your bandwidth. A webserver must keep an eye on connections and limit connections per second. This is serving 101. The default is no limit. Lighttpd can limit the throughput for each single connection (per IP) or for all connections. You also need to a use firewall to limit connections per second. In this article I will cover firewall and lighttpd web server settings to throttle end users. The firewall settings can be applied to other web servers such as Apache / Nginx and IIS server behind PF / netfilter based firewall.

FreeBSD 7.2 Review: Improved Virtualization

Posted on in Categories FreeBSD, Hardware, News, package management last updated May 2, 2009

FreeBSD is just plain old good UNIX with rock solid networking stack. It is quite popular amongst hosting companies, ISPs, portals (such as Yahoo) and a few large financial institutions because of its reliability, robustness and performance.

A new version of the FreeBSD is scheduled for release next week (4-May-2009). A beta 2 was made available for download few weeks ago for final round of testing before the official launch.

Lighttpd Install mod_geoip For Country / City Level Geo Targeting

Posted on in Categories CentOS, Debian Linux, FreeBSD, Gentoo Linux, Howto, lighttpd, Linux, Networking, package management, RedHat/Fedora Linux, Suse Linux, Ubuntu Linux, UNIX last updated March 29, 2009

Geolocation software is used to get the geographic location of visitor using IP address. You can determine country, organization and guess visitors location. This is useful for:

a] Fraud detection.

b] Geo marketing and ad serving.

c] Target content.

d] Spam fighting.

e] And much more.

mod_geoip is a Lighttpd module for fast ip/location lookups. In this tutorial you will learn about mod_geoip installation and php server side examples to determine visitors country.

Security Through Obscurity: MAC Address Filtering ( Layer 2 Filtering )

Posted on in Categories data center, fedora linux, FreeBSD, Gentoo Linux, GNU/Open source, Hardware, Iptables, Linux, Networking, RedHat/Fedora Linux, Security, Ubuntu Linux, UNIX, Windows, windows vista, Wireless networking last updated February 17, 2009

MAC Filtering (layer 2 address filtering) refers to a security access control methodology whereby the 48-bit address assigned to each network card is used to determine access to the network. Iptables, pf, and IPFW can block a certain MAC address on a network, just like an IP. One can deny or allow from MAC address like 00:1e:2a:47:42:8d using open source firewalls. MAC address filtering is often used to secure LAN or wireless network / devices. Is this technique effective?

How To Tail (View) Multiple Files on UNIX / Linux Console

Posted on in Categories data center, Debian Linux, Download of the day, fedora linux, File system, FreeBSD, Gentoo Linux, GNU/Open source, Howto, Linux, Linux Log Management, Monitoring, package management, RedHat/Fedora Linux, Suse Linux, Sys admin, Tip of the day, UNIX last updated February 9, 2009

The tail command is one of the best tool to view log files in a real time using tail -f /path/to/log.file syntax on a Unix-like systems. The program MultiTail lets you view one or multiple files like the original tail program. The difference is that it creates multiple windows on your console (with ncurses). This is one of those dream come true program for UNIX sys admin job. You can browse through several log files at once and do various operations like search for errors and more.