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Currency Traders Telnet Game

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A new, large Currency Traders game is up. To connect enter the following command from an xterm, konsole, or other terminal/command line window:

telnet teotwawkigames.com

It runs on port 23, just like traditional telnet. It's free to play and no software is required to play. All you need is an internet connection.

This is an old-school, no-graphics strategy game. All you need is a telnet client to play -- and every modern operating system comes with one. It's free and you can play anonymously. Just choose a name and a password and log in. If you don't know what to do, just press your H key for a Hint and a context-sensitive Tip.

This game is played in a persistent world where whatever you build, buy, or otherwise 'acquire' in the game will still be there tomorrow. Unless you make an enemy of another player, that is. PVP (player-versus-player) is always enabled here so other players can attack your deployed fortifications -- or even, heaven forbid, you.

This is a turn-based game that can be played any time of the day, night, or week. Each player is issued a certain amount of energy (turns) per day that is used to travel, trade, or play at the arcade in the several Malls. If you don't use your turns, they accumulate for as much as several months -- so there's no disadvantage to skipping a day or even a few weeks.

A slightly longer description of Currency Traders is here.
mail this link | permapage | score:9540 | -Ray, January 23, 2013

VPS: Xen vs. OpenVZ

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This is a short overview of the key differences between OpenVZ and Xen that you might consider when choosing a VPS. Note that this article is based on my opinions and that you must do your own research to determine which, if either, technology is best for you and your application.

First, some terminology. OpenVZ isn't fully virtualized and could be more properly referred to as a 'container', not a VPS. That shouldn't affect your choice. It's the technical differences that matter.

Cheap VPS offers are everywhere lately, it seems. However, upon closer inspection I saw that almost all of the low-priced offers were for OpenVZ. While both Xen and OpenVZ offer their advantages, I chose Xen. So, there's my first bias, right up front. :)

OpenVZ advantages:

  • Efficient (fast)
OpenVZ disadvantages:
  • Shared kernel (no custom kernel)
  • Shared memory with other users
  • Vendor can easily oversell, killing performance
Xen advantages:
  • Dedicated memory
  • fully virtualized (can run other kernels or even OS's)
  • vendor more limited in overselling
Xen disadvantages
  • Less efficient (more overhead due to a kernel-per-VPS)

You'll notice I left price out of the above comparison. In theory, there should be a small price advantage for OpenVZ. I don't know how big it should be but it pertains to two things: 1) Xen uses more memory due to each VPS having its own kernel, and 2) Xen uses more CPU, also due to the additional software layer required to virtualize the kernel.

In practice, however, the price gap appears larger than the above technical differences suggest it should be. I think the remainder of OpenVZ's price advantage is based on 1) the ability for a vendor to easily oversell OpenVZ, and 2) The price competition that results from some vendors overselling OpenVZ.

OpenVZ doesn't encapsulate its containers into a fixed amount of memory, so it runs processes in the host environment to monitor memory usage and kill processes as a container allocates more than its assigned amount.

As a result of this difference, loading down an OpenVZ container is problematic. To partially offset this disadvantage, most OpenVZ vendors offer 'burst' memory in addition to 'dedicated' memory. That is, the monitor process is set to allow the container to use more than its allocated memory -- for a short period of time. This messy situation results in a potentially unreliable environment as some of your processes may be arbitrarily killed -- at the busiest times.

Xen, on the other hand, allows the use of a swap space and excess memory allocation results in (hopefully) idle segments being rolled out to the swap area. While this is good for the memory-hungry VPS user, it can consume significant I/O capacity when memory is overallocated to the point of busy segments getting swapped out. This is bad for everyone sharing the underlying hardware.

I see Xen as clearly the superior technology. A Xen VPS feels and behaves more like a dedicated server. However, I still would have purchased OpenVZ at some price difference. After a bit of research, however, I located Xen VPS's at practically the same price as the cheapest OpenVZ containers. That made my decision easy.

With that said, keep in mind that a bad hosting vendor can ruin either technology through various means. Both technologies share the disk drives and I/O paths as well as the processor cores. Hardware can be poorly configured and managed in any case. A reputable vendor is probably the single most important consideration in choosing a virtual server.

Lastly, carefully check the 'allowed use' policy. Make sure your application is allowed on the server you intend to purchase. Note that due to their different characteristics, the allowed use policy may differ between OpenVZ and Xen for the same host. Also, it's good to understand the memory usage characteristics of your applications. If you know how much memory/swap they require on a physical system, it'll probably work with that same amount of memory/swap on Xen.

[I'll post a review shortly of my current VPS vendor and I will then add a link to that article here.]

mail this link | permapage | score:9490 | -Ray, June 13, 2011

Apple DIY Repair

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I won't be buying any more Apple products. Here's why:

I'm generally capable of repairing my own equipment and can recognize when self-repair has been deliberately undermined. I recently had to replace a hard drive in an early generation white Intel iMac. Innocently, I believed the interior was accessible and serviceable in the manner of the externally identical white PowerPC iMacs.

No such luck. Not only do you have to remove the LCD to get to the hard drive, but you must also remove shielding around the LCD -- mostly by tearing it to bits. No doubt it is attached this way so that an authorized Apple technician will be able to confidently void your warranty if you've ever worked on the system yourself.

You'll also need a #10 torx magnetic screwdriver. And, no, #10 torx bits just won't do due to the narrow and deeply recessed screw holes. Also, since most torx screwdrivers aren't magnetic, you'll probably need to tape the screws to the screwdriver to reattach the LCD. Good thing there's a hardware store near you.

Oh, and don't forget to pick up some rubber cement to 'properly' reattach the hard drive temperature sensor while you're out looking for magnetic torx screwdrivers.

Considering the logical design of its predecessor and the tamper-evident shielding, I'm certain that this machine has been deliberately designed to prevent the owner from performing DIY upgrades and repairs.

While that is all quite annoying, at least working on the system is possible for someone with experience and determination.

Now, Apple has improved their anti-customer techniques with the 'Pentalobe' screw. It doesn't solve any problem but one: it'll keep customers from even being able to open the case.

If you're curious about Apple's evil new invention, you can read its rap sheet and view its mug shot here.
mail this link | permapage | score:9476 | -Ray, January 25, 2011

Install a Mail Server with Antivirus and Antispam in minutes

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This article illustrates a situation where you need to set up your own mail server (be it your home mail server, or a small office one). It actually shows that, if using an integrated service mail server, anyone can do the job, all in a matter of minutes.

AXIGEN Mail Server, the solution chosen for this example, can send and receive e-mails securely via "mydomain.com" and is able to retrieve them in a WebMail interface - this means that it includes all mail services needed for a fully functional mail server (SMTP, IMAP, POP3, WebMail, WebAdmin).

To get an idea of the amount of time you can spare by installing such a solution, just think of all the different open source applications you would need to install instead (i.e. an MTA, Squirrelmail for Webmail, QmailAdmin for web configuration, Courier for IMAP and POP3 and many others.)

AXIGEN Mail Server can virtually integrate with any Antivirus/Antispam application and it comes with built-in connectors ClamAV Antivirus and SpamAssassin. The second part of this article shows you how to install these applications and configure these connectors for use with AXIGEN.

Thus, at the end of this process which can take up half an hour at most, you will not only have your mail server up and running, but also virus and spam protection for your incoming and outgoing mail traffic.

AXIGEN runs on several Linux distributions (Gentoo, Redhat/Fedora Core, Slackware, Debian, Ubuntu, Mandrake/Mandriva, SUSE), on BSD versions (FreeBSD, OpenBSD and NetBSD) and on Solaris but for the purpose of this article, let's suppose you are setting up your mail system on a Fedora Core 6 platform.In five easy steps, you will have your server installed, your primary domain running and access to the Web configuration interface (WebAdmin).

1. Download / unpack corresponding package

Download AXIGEN rpm package from the AXIGEN website (packages are available as 30 day evaluation versions). Save the corresponding package for Fedora Core 6 "axigen-2.0.4.i386.rpm.gcc4.tar.gz" on your local machine and unpack the file, by issuing in the same directory as the download file:
tar xzvf axigen-2.0.4.i386.rpm.gcc4.tar.gz

2. Install command

Then, in order to install the RPM package, issue (while logged in as root) the following command, from the same directory as the rpm file:
rpm -ivh axigen-2.0.4.gcc4-1.i386.rpm
This will create the entire directory structure needed for AXIGEN to run. After the installation, no daemons or related application will be started.


3. Configuration options

AXIGEN provides several configuration options (configuration file, Command Line Interface), but the most intuitive and comprehensive one is WebAdmin, the Web configuration interface.

The corresponding WebAdmin service is enabled by default, as well as the other default services: IMAP, Logging, POP3, Processing and SMTP.

4. Initial configuration

The first configuration steps take place using the configuration wizard. You will set the administrator's password, select which services are started and what interfaces will be used. In this stage of the setup you also create the primary domain that your server will use.


The wizard can be run by issuing the following command in the console right after the installation of the package has finished:
/opt/axigen/bin/axigen-cfg-wizard
NOTE: You have to make sure you do not start the mail server before the initial configuration.

5. Start AXIGEN

You can then start AXIGEN, using its initscript, by issuing this command:
/etc/init.d/axigen start
Now that your server is running, you can connect the antivirus and anti-spam applications. By default, AXIGEN comes with connectors for the ClamAV Antivirus and SpamAssasin Antispam application. The setup process below describes how to make these two applications work with AXIGEN. However, note that AXIGEN implements a proprietary filter scripting language that allows you to implement connectors for any third party Antivirus and Antispam applications.

Connecting to ClamAV


A. Install ClamAV (daemon), on the same machine on which AXIGEN Mail Server is installed. Follow these steps in order to configure ClamAv for use with AXIGEN and start the clamd daemon.

1. Install clamav-server, using yum (Yellow Dog Updater, Modified):
yum install clamav-server
2. Copy the sample config file shipped with clamav-server:
cp /usr/share/doc/clamav-server-*/clamd.conf /etc/clamd.d/axigen.conf
3. Edit: /etc/clamd.d/axigen.conf
# comment out the Example line 
# Example
# insert/modify the following lines:
LogFile /var/log/clamd.axigen
PidFile /var/run/clamd.axigen/clamd.pid
LocalSocket /var/run/clamd.axigen/clamd.sock
User axigen
4. Create a link to the clamd binary:
ln -s /usr/sbin/clamd /usr/sbin/clamd.axigen
5. Create the run directory, where the PID file and clamd socket will be stored, and change its permissions:
mkdir -p /var/run/clamd.axigen chown axigen:axigen /var/run/clamd.axigen
6. Create and setup the initscript:
cp /usr/share/doc/clamav-server-*/clamd.init /etc/init.d/clamd.axigen 
chmod 755 /etc/init.d/clamd.axigen /sbin/chkconfig clamd.axigen on
7. Edit: /etc/init.d/clamd.axigen and modify the following lines, as specified below:
# description: The clamd server running for axigen CLAMD_SERVICE=axigen
8. Finally, start the clamd daemon:
/etc/init.d/clamd.axigen

B. Configure AXIGEN antivirus filter at server level using WebAdmin

In order to activate the ClamAV filter, go through the following steps:

In the "Server" context, click on the Add new filter button. This will open up and display the Active Filter list. It is empty right now, so we need to add the clamav filter to the list.



In the Priority field, enter a priority between 0 and 500 (a filter with priority 0 will be applied first and the one with 500, last).

Important - the domain-level filters have the priority limited to range 100-400 and the user-level filters are limited to the 200-300 range. A value of "10" should be fine, leaving you space to apply some other future filters before this one.

After setting the filter priority, select the socket value from in the Filter type dropdown list and the clamav value from the Filter Name list.

In the Apply on checklist, select the relay option, to apply the filter on outgoing mails. To make sure you scan both incoming and outgoing mails, you have to create the filter and select both values, local and relay.

In AXIGEN, it is possible to enable filters either at domain or user level, in the corresponding WebAdmin tabs. The filters activated at server level will be automatically applied for all domains and accounts. However, you have the possibility to add additional filters at domain or account level.

Connecting to SpamAssasin


The process for Connecting SpamAssassin is similar and even less time-consuming as no configurations are necessary after the product installation.

C. Install SpamAssassin using the yum application:
yum install spamassassin
No further configurations are necessary.

D. Configure SpamAssassin at server level, using Webadmin

The connector for SpamAssassin is a socket filter for AXIGEN, so the configuration procedure is the same as for ClamAV. The difference would be that for SpamAssassin, a TCP socket is more likely to be used.

Also, when activating the SpamAssassin filter, you need to keep in mind the following:
  • Enter a different priority value for the SpamAssasin filter (if you have chosen 10 for ClamAV, choose a higher value for SpamAssassin in order to apply this filter after ClamAV in the filtering chain)
  • Select the corresponding filter name, spamassassin in the Filter name list

Access AXIGEN WebMail


At this step of the way, your mail server is ready to go, and you can also you can access the AXIGEN WebMail to send and receive test messages. Then, use the full email address and password to log on to AXIGEN WebMail, at the default address: http://127.0.0.1:8000, or use the address you specified in the initial configuration phase when you ran the setup wizard.


Now you're really done: you can securely send and receive messages from your home domain and easily make any further configurations, to accommodate your specific network requirements. As you have seen, installing all mail services from one single executable and an intuitive Web configuration interface make things a lot easier and a lot less time-consuming.

Authors:
Liviu Anghel, Chief Security Officer, Gecad Technologies
Ciprian Negrila, Technical Support Engineer, Gecad Technologies

read more...
mail this link | permapage | score:9385 | -Kayla Vincent, February 6, 2007
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