How to know if your computer has a virus

A common question from users when dealing with computer viruses is how to know if your computer has a virus. Actually this is not a user concern to know if their computer is infected by viruses or not, but only if they had anti virus programs installed. That's why user recommended to at least install a free virus protection programs on their computer to protect system, data, programs or documents from virus infection. But if don't have it or you already used your computer without anti viruses installed before, then you have to track it down by your self based on several traits for the sign of viruses hosted on your computer.


1. Computer become lag or crash very often
Lag and crash can be a sign of viruses running on your system. They usually use some computer resource in the background such as memory, cpu and some also using internet to communicate to their server. Even thought it can be also problems on your hardware and system, but when it come in sudden then you have to warn your self as it could be viruses.

2. Some missing features or tools on Windows
This is definitely things that caused by viruses. If you felt that you didn't remove or delete anything on Windows but you can't find tools such Folder Options, Task Managermsconfig and regedit from your computer, than that certainly viruses roaming on your computer.

3. Error messages while opening Office documents
This is one of the most annoying virus, especially if you're working with Office documents everyday. Some of them injected them self into document files, some others pretend to be document files while hiding or removing the real documents from hard drive.

4. Accessing usb flash drive taking longer than usual
Most of them spreading them self to another computers though usb flash drive. When you plug in a flash drive into computer and then you see a warning or something suspicious running such as media scanning, or alert for un-formatted media, than you should be aware as it could be an autorun.inf on the drive tells computer to do so which is actually a way for viruses to inject them self into computer.

5. Missing or hidden files/documents on usb flash drive
If your computer infected by viruses, they sometime monitoring in the background waiting for a usb drive to be plugged into computer. When it happen, they usually attach infected files into flash drive by disguising as the files of documents inside the flash drive and then hiding the real files. You can retrieve the hidden files using attrib command. In the other cases files or documents inside usb drive sometime moved or even removed from the flash drive.

6. Can not access safe mode
In order to protect them self, they prevent user to access some windows tool (read section 2) including Windows safe mode. So when you restart computer and hit F8 to choose boot mode, and then select safe mode, you computer will be halted by blue screen of death (BOSD) or sometime it will restarted by it self.

7. Playing with keyboard and Mouse
In some rare cases, viruses also playing with keyboard or Mouse. When you can't control your mouse. like it always pointing to the middle of screen, or it always typing a certain character or can't use keyboard, than it could be malwares playing with your hardware.

8. Slow down or block internet access, block certain website 
If you can't use internet like you always be, or internet stats showing high bandwidth usage while you're only opening Facebook, or you can't access certain website like Microsoft or Anti virus website, or you completely can't use internet while your ISP said they're fine, than that could be sign of spywares or Trojan.

9. To many popups
If you suddenly see popups attacking your screen, your computer might be infected by adwares. Adwares usually send popups to your screen while your surfing to internet.

10. Programs stop working or missing system warning on startup
Sometime when you start-up you computer, you'll see several warning of missing system files. This could be due to the files is broken or deleted, or it's only a fake warning send by viruses. This could also caused for some programs or applications stop working.


The most important things is that you can't manually remove the viruses, well.., you actually can, but that's not an easy task since viruses usually spread or evolve them self to many things on computer, for example system files and registry. So you'll need lot of time to track all the files and registry created by viruses. That's why if you sure that the computer is infected, the first thing you have to do is install anti virus programs and let the program do the cleaning job. It is wise to have an anti viruses installed on your PC and updated frequently even if your computer wasn't attacked by viruses.


Simple bandwidth with exception management using cbq.init on Linux

In hotspot we got Mikrotik to handle bandwidth for every users. But Mikrotik only a box to handle client that connect to our network through wireless hotspot. We have main router installed with Linux (Centos 6.3) and also installed with several services such as web and MySql database server which is also a router for the hotspot.

We have to admit that Mikrotik it a great tool to deal with traffic, but Linux is better in serving various internet services. The problem is that our Linux box also is a main router for other users including Mikrotik hotspot that connect through LAN cable. Those users need high bandwidth for accessing local services in our network but will be be treated as other hotspot user if they want to access to internet.


Somehow we can't find any tutorials and examples around, so we want to share a simple rules we've created to managed bandwidth with cbq.init, which will managing high bandwidth for local or specific address while also limiting access to internet. Here it is:

Unlimited bandwidth to specific services or addresses

We created 4 cbq files in /etc/sysconfig/cbq which consists of :

cbq-0002.xxxx
cbq-0003.xxxx
cbq-0004.xxxx
cbq-0005.xxxx



The first two files (cbq-0002.xxxx and cbq-0003.xxxx) are created with high priority. This files is needed to give high bandwidth allocation for local or specific address. cbq-0002.xxx controlling unlimited download for specific address on local network devices, in this case eth2 (eth1 is device that connect to internet, eth2 connect to local network).

DEVICE=eth2,1000Mbit,100Mbit
RATE=1000Mbit
WEIGHT=100Mbit
PEAK=1000Mbit
LEAF=sfq
QUANTUM=1500
PRIO=1
ISOLATED=no
RULE = 192.168.32.0/24, #download from a specific network
RULE = 203.24.50.15, #download from a specific address
RULE = 10.10.8.0/24,10.10.8.0/24 #download from local to local


cbq-0003.xxx controlling unlimited upload traffic to specific address on internet devices.

DEVICE=eth1,1000Mbit,100Mbit
RATE=1000Mbit
WEIGHT=100Mbit
PEAK=1000Mbit
LEAF=sfq
QUANTUM=1500
PRIO=1
ISOLATED=no
RULE = 10.10.8.0/24,192.168.32.0/24 #upload to specific network
RULE = 10.10.8.0/24,203.24.50.15 #upload to specific address


As you can see, both files using highest priority (PRIO=1), which will give high access to only specified address provided on RULE on the file.

Limit for several users to other than exception address

cbq-0004.xxxx and cbq-0005.xxxx contain of bandwidth limiting rules with lower priority (PRIO=8) for specific users. cbq-0004.xxxx controlling download for local devices, all users provided in this rule will be limited to up-to 1Mbit download to internet,

DEVICE=eth2,1000Mbit,100Mbit
RATE=1Mbit
WEIGHT=100Kbit
PEAK=1Mbit
LEAF=sfq
QUANTUM=1500
PRIO=8
ISOLATED=no
RULE = 10.10.8.1
RULE = 10.10.8.2
RULE = 10.10.8.3
RULE = 10.10.8.4
RULE = 10.10.8.5


And cbq-0005.xxxx controlling upload for internet devices, all users will be limited to up-to 1Mbit upload to internet.

DEVICE=eth1,1000Mbit,100Mbit
RATE=1Mbit
WEIGHT=100Kbit
PEAK=1Mbit
LEAF=sfq
QUANTUM=1500
PRIO=8
ISOLATED=no
RULE = 10.10.8.1,
RULE = 10.10.8.2,
RULE = 10.10.8.3,
RULE = 10.10.8.4,
RULE = 10.10.8.5,



I hope this would helpful for peoples who still want to use cbq.init in their Linux box, although peoples said that htb.init is better than cbq.init, but for us those scripts are enough already.


Our alternatives to commercial software

Although for business purpose, you might prefer to choose Commercial software rather than open source, but you may also like to see what we used to use as alternative our daily software which also doing as great as commercial software.


Lazarus as alternative to Delphi
Since 2011 we decided to try Lazarus as our programming IDE.
Lazarus is a free cross-platform IDE which provides a Delphi-like development experience for Pascal and Object Pascal developers. It is developed for, and supported by, the Free Pascal compiler (Lazarus Wiki).

PSPP as alternative to SPSS
Some of us use this software in related to their educational research and this software work similar to SPSS.
PSPP is a program for statistical analysis of sampled data. It is a Free replacement for the proprietary program SPSS, and appears very similar to it with a few exceptions (PSPP Website).

ProjectLibre as alternative to Microsoft Project
If you work on a project development, you might know this software already, Microsoft Project. Recently we've found this open source software accidentally while browsing. This software name somehow remind me of LibreOffice.
ProjectLibre is an open source project management software. It intends to be a complete desktop replacement for Microsoft Project. ProjectLibre runs on the Java Platform, allowing it to run on a variety of different operating systems (ProjectLibre Wiki).
Those are powerful replacement for commercial software and really worth to try.