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Unix+clones

Streaming music with SlimServer

Post date: June 15, 2005, 16:06 Category: Network Views: 4210 Comments
Tutorial quote: Converting your CD collection into MP3 or another digital file format gives you the ability to enjoy the music on your computer and stream it all over the house and the Internet. To do the latter, however, you have to install and configure a streaming server on your computer. That might sound like a daunting task, but there is a streaming server application that makes the whole process pretty painless. SlimServer from Slim Devices is a cross-platform streaming server that runs on Windows, Linux, and Mac OS X and supports a wide range of formats, including AAC, AIFF, FLAC, Ogg Vorbis, MP3, WAV, and WMA. Although it was developed to stream music files to Slim Devices' Squeezebox2 hardware player, it works perfectly with any software MP3 player capable of working with network streams.
Linux

Change Ctrl + Alt + Delete Behavior To Open System Monitor, in Linux

Post date: September 24, 2009, 12:09 Category: Miscellaneous Views: 2943 Comments
Tutorial quote: Actually, I've written this post before (quite a few months ago) but then deleted it because it didn't work. In the mean time, I found out why, so I decided to post it again. I find pressing Control + Alt + Delete to open up System Monitor to be very useful, especially for Windows users who are used to it and may actually press this quite a few times before realizing it doesn't do anything or what it does in Windows. Using System Monitor, you can preview all running processes, end or kill them, see how much CPU a process is using, CPU + memory + network history, available disk space and even change how much CPU a process should use.

There are 2 ways of changing Ctrl + Alt + Delete behavior to open System Monitor: one if you are running Compiz, and one for Metacity, only to use if you are not running Compiz.
Linux

The Linux /proc Filesystem as a Programmers' Tool

Post date: June 22, 2005, 09:06 Category: Programming Views: 4200 Comments
Tutorial quote: My entry into systems programming was guided by my desire to understand further the operating systems I was working with daily as a contract UNIX and, later, Linux system administrator. The result of this was ifchk, a packet sniffer detector I wrote in C and released in June of 2003. ifchk initially was written under IRIX and then ported to Linux, mostly under the 2.4 kernel. The current ifchk revision, beta 4, recently was released and beta 5 is on the way.

My work on ifchk has allowed me to examine programmatically several areas of operating system functionality. Examples include the Linux netlink(7) and rtnetlink(7) facilities, device control--that is, network interfaces--via ioctl(2), signals and proc, the process filesystem. Proc and its ability to display a wide array of data concerning the runtime state of a system are the focus of our discussion here.
Linux

Connecting to a Wireless LAN with Linux, Part 2

Post date: April 13, 2005, 19:04 Category: Hardware Views: 4499 Comments
Tutorial quote: In Part 1 we reviewed hardware options, which wireless utilities should be present, how to use Windows drivers, and how to be open to connect to any available wireless access point. Today we'll cover configurations on Red Hat- and Debian-type systems, basic security, and hardware discovery.

Wireless connectivity can be rather overly friendly, allowing connections from anyone. This howto assumes you have a wireless access point on a LAN, which can be all wireless or mixed wired and wireless. You don't want it wide open to just any random person with a desire to snoop on your network or "borrow" your bandwidth, but you want some access controls and security. Your access point should have a unique SSID (service set identifier), WEP (wireless equivalent privacy) or WPA/WPA2 (Wi-fi protected access) set up and working, and either a DHCP server or a pool of assigned IP addresses for clients.
Linux

Creating a safe directory with PAM and Encfs

Post date: June 7, 2006, 20:06 Category: Security Views: 4192 Comments
Tutorial quote: Now, in my network (and others) the credentials provided at login could (and should) be used by those programs. How can you retrieve these credentials, providing enough security?
With a the PAM modules pam_script it's possible to store the password in a file, which will be used by fusemb and mount.cifs to read the password from.

To achieve security, one could make the user logging in owner and deny read/write for anybody else. Remove this file when the user ends his/her session.
This is enough, for runtime. But I was wondering, but what if the system crashes, and the file with the credentials remains on the harddrive? Anybody who is able to mount this harddrive with for example a lifecd, can read this file!

That's why I was looking for a way to encrypt this file.

With encfs this is very possible! At run time it gives an interface to encrypted files and directories, which does only exist at runtime! When the system is not running, there are only encrypted files, useless when you do not know the key to it. And this key is exactly the (encrypted) password! That's why I've chosen for a combination of PAM and Encfs.
Linux

Upstream Provider Woes? Point the Ping of Blame

Post date: April 14, 2005, 12:04 Category: Network Views: 3115 Comments
Tutorial quote: Your users are complaining that "the Internet is, like, all slow." Users are always complaining, but you're seeing a lot of timeouts when you check mail, surf the Web, or try to log in for remote administration. Or even worse, latency is so bad that you keep getting killed all to heck in your favorite gory violent online multi-player game, so you know there is a problem. But there a lot of potential bottlenecks between your PC and the outside world, like your Internet gateway, proxy server, firewall, Internet service provider, and so forth, so where do you begin?

One of the best and most versatile network tools you can have is a notebook PC running Linux. This lets you plug in anywhere to run tests and find out what is going on. Make it a nothing-to-lose box--don't keep data on it so you can wipe and reinstall the operating system as necessary, because you want to be able to run tests outside of firewalls. Don't run any services. You can put a minimal iptables firewall on it, as there is no point in being totally exposed, but keep it simple. (Use MondoRescue to make a system snapshot for fast restores.)
FreeBSD

Installing FreeBSD on IBM Netvista S40

Post date: May 8, 2005, 21:05 Category: Installing Views: 4351 Comments
Tutorial quote: In this note we shall talk about installing FreeBSD on a very interesting and elegant machine: IBM Netvista S40. In its creator own terminology, it is "legacy-free". The computer has no parallel, serial, AT keyboard, nor PS/2 mouse ports. No floppy controller either. Instead, it has 5 USB ports (2 frontal and 3 rear) connected to a single USB controller. Besides these USB ports, the system only counts with standard video and audio connectors. The video controller is Intel 82810E SVGA and audio chip is Intel ICH 82801AA, both integrated onboard. The CPU is Intel PIII at 866MHz. The machine is further equipped with a fast Intel Pro PCI network adapter containing a PXE/RIPL boot prom. A quiet 20G Quantum Fireball HDD and a Liteon ATAPI CD-ROM, both connected as masters, constitute the storage subsystem. The case is Flex ATX, a small form factor.
Linux

Removing A User

Post date: April 8, 2006, 00:04 Category: System Views: 4841 Comments
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

Three tools to help you configure iptables

Post date: May 25, 2005, 14:05 Category: Network Views: 3806 Comments
Tutorial quote: Every user whose client connects to the Internet should configure his firewall immediately after installation. Some Linux distributions include firewall configuration as a part of installation, often offering a set of defaults configurations to choose from. However, to ensure that your machine presents the minimum "attack surface" (a measure of the number of vulnerable ports, user accounts, and sockets exposed to attack) to the predatory inhabitants of the Internet, you may need to do some manual configuration of your firewall. Here are three tools that can help.
The Linux kernel (version 2.4 onwards) contains a framework for packet filtering and firewalling using netfilter and iptables. Netfilter is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. Iptables is a generic table structure for the definition of rulesets. Each rule within an IP table consists of a number of classifiers (iptables matches) and one connected action (iptables target). Iptables has extensive documentation that can be accessed online or by typing man iptables at the command line. Yet despite the depth of the documentation available for iptables, its complexity can be baffling.
Linux

Linux Web Filtering in 7 steps

Post date: April 12, 2005, 18:04 Category: Network Views: 4822 Comments
Tutorial quote: How to install a transparent Squid proxy server with real-time HTTP virus scanning on Mandrake 10.0 using DansGuardian and ClamAV?

People quickly and easily access volumes of research on the Internet and correspond with a mouse click. For more and more companies, content filtering is part of the large battle to combat all kinds of online threats, including hackers, worms and viruses. Linux content filtering allows administrators to configure and manage Internet access across the entire network and to block unwanted Web content like pornography, shopping Web sites, games and gambling.

This guide contains all the necessary information for installing and understanding the architectural layout of the implementation. It was written with the assumption that you understand how to install programs and have a basic understanding of Linux Mandrake. This includes installing Linux Mandrake and RPM packages, editing files, making directories, compiling software and understanding general UNIX commands. This guide doesn’t explain how to use or configure Squid, DansGuardian and ClamAV but information on where to obtain this information can be found in the “Additional information” section.
Web-based applications and online marketing solutions - LumoLink