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Virus is blocking Internet access, how to eliminate it?

Internet access is blocked due to malware infection, how to eliminate it?

This tutorial describes how to re-establish Internet access if blocked by malware. Some malware variants modify Internet browser settings by adding a Proxy Server. In these cases, you will be unable to visit any websites, and thus not able to download the required software to eliminate the security infections. Other types of malware change the computer's DNS settings or add various entries to your operating system's Hosts file. By altering these settings, computer viruses can cause redirect issues or completely block the Internet connection. If you cannot access the Internet, and suspect that this is caused by a virus infection, check the settings below.

If you cannot access the Internet due to a malware infection, first try booting your computer in Safe Mode with Networking. You can find out how to do this in our 'how to remove spyware?' section. If you are still unable to access the Internet, use these instructions:

Check Proxy Server settings in Internet Explorer:

1. Open Internet Explorer. At the top right corner of the main window, click the 'wrench' icon. In the opened drop down menu, choose 'Internet Options'.

Internet Explorer Internet settings

2. In the opened window, select the 'Connections' tab.

Internet options connections tab

3. In the 'Connections' tab, click the 'LAN settings' button.

Internet Explorer lan settings

4. In the 'Lan settings' window, ensure that the 'Use a proxy server for your LAN' option is not checked (otherwise, uncheck it and click 'OK').

lan settings proxy server

Check your computer's DNS settings:

1. Click the 'Windows logo' (Start button).

click start

2. In the opened menu, select 'Control Panel'.

control panel

3. In the opened window, click 'Network and Internet'.

network and Internet

4. In the opened window, click 'View network status and stats'.

view network status and tasks

5. Click 'Local Area Connection'.

local area connection

6. In the opened window, click the 'Properties' button.

local area connection properties

7. In the 'Properties' window, select 'Internet Protocol (TCP/IP)' and click the 'Properties' button.

Internet protocol settings

8. In the opened window, check if 'Obtain DNS server address automatically' is checked.

obtain DNS server automatically

Check your operating system's Hosts file.

Locate your Hosts file. You should find it at %systemroot% \system32\drivers\etc (commonly, it will be c:\windows\system32\drivers\etc). Open the Hosts file with Notepad and verify that no unusual values have been added to it.

These are the default values, and yours should be the same:

Default Windows XP Hosts File:

# Copyright (c) 1993-1999 Microsoft Corp.

#

# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.

#

# This file contains the mappings of IP addresses to host names. Each

# entry should be kept on an individual line. The IP address should

# be placed in the first column followed by the corresponding host name.

# The IP address and the host name should be separated by at least one

# space.

#

# Additionally, comments (such as these) may be inserted on individual

# lines or following the machine name denoted by a '#' symbol.

#

127.0.0.1 localhost

Default Windows Vista Hosts File:

# Copyright (c) 1993-2006 Microsoft Corp.

#

# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.

#

# This file contains the mappings of IP addresses to host names. Each

# entry should be kept on an individual line. The IP address should

# be placed in the first column followed by the corresponding host name.

# The IP address and the host name should be separated by at least one

# space.

#

# Additionally, comments (such as these) may be inserted on individual

# lines or following the machine name denoted by a '#' symbol.

#

127.0.0.1 localhost

::1 localhost

Default Windows 7 Hosts File:

# Copyright (c) 1993-2006 Microsoft Corp.

#

# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.

#

# This file contains the mappings of IP addresses to host names. Each

# entry should be kept on an individual line. The IP address should

# be placed in the first column followed by the corresponding host name.

# The IP address and the host name should be separated by at least one

# space.

#

# Additionally, comments (such as these) may be inserted on individual

# lines or following the machine name denoted by a '#' symbol.

#

# localhost name resolution is handle within DNS itself.

# 127.0.0.1 localhost

# ::1 localhost

After checking and correcting these settings, your Internet connection should be back to normal. If you are dealing with malware infections, we recommend downloading anti-spyware software from our Top Anti-Spyware programs list and running a full system scan.

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About the author:

Tomas Meskauskas

I am passionate about computer security and technology. I have an experience of 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an editor for pcrisk.com since 2010. Follow me on Twitter to stay informed about the latest tech news or online security threats. Contact Tomas Meskauskas.

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