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Search results for Using the 'snort' Intrusion Detection System

Linux Removing A User
Post date: April 7, 2006, 20:04 Category: System Views: 10
Tutorial quote: Employee turnover in most organizations runs high. So unless you run a small shop with a stable user base, you need to learn how to clean up after an employee leaves. Too many so-called system administrators do not understand the stakes involved when they manage users. Disgruntled former employees can often cause significant trouble for a company by gaining access to the network.

To remove a user, you need to learn to manage all of his or her files, mailboxes, mail aliases, print jobs, recurring –(automatic) personal processes such as the backing up of data or remote syncing of directories, and other references to the user. It is a good idea at first to disable the account in /etc/passwd, after which you can search for the user's files and other references. Once all traces of the user have been cleaned up, you can remove the user completely—but if you remove the entry from /etc/passwd while these other references exist, you have a harder time referring to them .

When you remove a user, it's a good idea to follow a pre-determined course of action so you don't forget any important steps; it may even be a good idea to make a checklist so that you have a routine. Following, you will find several items requiring attention.
Linux Creating Really Teensy ELF Executables for Linux
Post date: April 12, 2005, 14:04 Category: Miscellaneous Views: 34
Tutorial quote: If you're a programmer who's become fed up with software bloat, then may you find herein the perfect antidote.

This document explores methods for squeezing excess bytes out of simple programs. (Of course, the more practical purpose of this document is to describe a few of the inner workings of the ELF file format and the Linux operating system. But hopefully you can also learn something about how to make really teensy ELF executables in the process.)

Please note that the information and examples given here are, for the most part, specific to ELF executables on a Linux platform running under an Intel-386 architecture. I imagine that a good bit of the information is applicable to other ELF-based Unices, but my experiences with such are too limited for me to say with certainty.

The assembly code that appears in this document is written for use with Nasm. (Besides being more appropriate for our needs, Nasm's syntax beats the hell out of AT&T syntax for anyone who learned x86 assembly language before learning to use Gas.) Nasm is freely available and extremely portable; see http://nasm.sourceforge.net/.

Please also note that if you aren't a little bit familiar with assembly code, you may find parts of this document sort of hard to follow.
Unix+clones Keeping Your Life in Subversion
Post date: October 2, 2005, 12:10 Category: Software Views: 119
Tutorial quote: I keep my life in a Subversion repository. For the past five years, I've checked every file I've created and worked on, every email I've sent or received, and every config file I've tweaked into revision control. Five years ago, when I started doing this using CVS, people thought I was nuts to use revision control in this way. Today it's still not a common practice, but thanks to my earlier article "CVS homedir" (Linux Journal, issue 101), I know I'm not alone. In this article I will describe how my new home directory setup is working now that I've switched from CVS to Subversion.

Subversion is a revision-control system. Like the earlier and much cruftier CVS, its purpose is to manage chunks of code, such as free software programs with multiple developers, or in-house software projects involving several employees. Unlike CVS, Subversion handles directories and file renaming reasonably, which is more than sufficient reason to switch to it if you're already using CVS. It also fixes most of CVS's other misfeatures. Subversion still has its warts, though, such as an inability to store symbolic links and some file permissions, and its need for twice as much disk space as you'd expect thanks to the copies of everything in those .svn directories. These problems can be quite annoying when you're keeping your whole home directory in svn. Why bother?
Linux The Serial Console
Post date: April 14, 2005, 09:04 Category: Hardware Views: 71
Tutorial quote: In these modern times, a hardworking admin might be tempted to turn her back on the Old Ways, and indulge in increasingly exotic methods of interfacing with servers: SSH over ethernet, USB, Firewire, wireless, infrared, KVM switches, VNC, VPN... next stop: direct neural implants.

There's one old timer that still has useful place in the admin's tool kit: the serial console. Sure, it's slow and funky. But there are times it can be a real lifesaver. When nothing else works, it's a direct pipeline into your system. It's simple and cheap. You don't need to install drivers or expansion cards, it's just there.

Administration via serial console is common in data centers. Just imagine the nightmare of trying to connect all those rack units to keyboards and displays. The cabling can be extended to a nice comfortable ops center (well, an ops center, anyway). (This Lantronix Console Manager is an example of the type of device used to administer these.)

There are a number of ways to make the physical connection. You can connect an external modem--the kind us old timers fondly refer to as "real" modems--and do remote administration via dialup. It couldn't be any simpler, just dial direct. Or grab a null modem cable, connect to a laptop or a nearby workstation, and you have an instant terminal.
Unix+clones How to Set Up a Jabber Server
Post date: April 12, 2005, 12:04 Category: Software Views: 37
Tutorial quote: Unless you have been living under a rock for the past few years, you must have heard about instant messaging and how it has changed the world of communications over the Internet. According to http://www.webopedia.com, Instant Messaging (IM) is a service that alerts users when their friends or colleagues are on line and allows them to communicate in real time through private online chat areas. Two of the most popular IM services are AOL Instant Messenger (AIM) and MSN Messenger. Unfortunately, most of the publicly available servers use proprietary protocols that only allow you to communicate with users on the same system. These systems are not compatible with each other and can't be accessed from other clients.

Jabber is an open source implementation of the IM server that aims to change this. It uses streaming XML protocols that are free, open, and public. These protocols have been formalized by the Internet Engineering Task Force (IETF) as the approved instant messaging and presence technology under the name of XMPP. The first Jabber technologies were developed in 1998 by Jeremie Miller and is now used on thousands of servers world-wide to enable millions of users to communicate with each other.

The biggest advantage of the Jabber server when compared with commercial IM servers is that, since it is open source, anyone can run a Jabber server and it can be restricted to a specific community like a company work force or a group of friends. In this article, I will document the steps I took to set up a Jabber server and how I managed to overcome the difficulties I faced. Hopefully this will make it easier for you to set up your own Jabber server.