AVAST antivirus completely blocks the local network on Windows XP. No Internet connection after removing the virus After removing Avast, the Internet disappeared

If you are faced with a lack of access to the Internet or some sites have stopped opening, then two options are possible: a virus is blocking access to some sites or your antivirus has removed a malicious program that changed the settings operating system defining a connection to the Internet. These may be browser proxy server settings, settings network card(Internet Protocol version 4), LSP stack configuration, etc.

As a result, you are faced with a situation where websites stop opening. Messages appear that “The web page is unavailable”, “You are not connected to the network”, “The proxy server is not responding” and other similar ones.

Ways to solve the problem “No Internet access”

The instructions below will help you solve problems with Internet access. Moreover, a variety of methods are used, from the simplest to those requiring special programs. Do them one by one. If Internet access is restored at any stage, then you can stop and not perform the following. If you have any questions, leave a comment below, ask a question in the section on our website, or contact us for help.

1. Restore your browser's proxy server settings.

Internet Explorer, Microsoft Edge and Google Chrome

All three of these browsers Internet Explorer, Microsoft Edge And Google Chrome use the same proxy server settings. To return them to their original values, do the following.

Launch Internet Explorer. Click on the gear-shaped button located on the right top corner browser(). A menu will open as shown in the following picture.

Click on the item Browser properties. You will be shown a window with several tabs. Select a tab Connections.

Click on the button Network setup as shown below.

In the section Proxy server uncheck the box next to the inscription Use a proxy server for local connections . Click OK and again OK.

Mozilla Firefox

Launch Firefox. Open the browser menu by clicking on the button in the form of three horizontal stripes (), which is located in the upper right part of the window. You will see the main Firefox menu, like in the picture below.

Here click on the gear icon with the inscription Settings. A window will open in front of you with Firefox settings. Click on the inscription Additional.

In the window that opens, in the section Compound, click on the button Tune. This action will open the settings that determine which proxy server the browser should use.

Select an item No proxy and click on the button OK. Restart your browser.

2. Restore Internet Protocol version 4 settings.

Windows XP, Vista, 7

Click on the button Start, in the menu that opens, select Network connections .

Windows 8, 8.1, 10

Press on the keyboard at the same time Windows keys and the X(H) key. A menu will open as in the following figure.

Select an item Network connections.

A window will open in front of you with a list of all network connections.

Click on the name of your adapter (network card) and select Properties.

A window will open with the properties of the selected network adapter. In the list of components, find the item Internet Protocol Version 4(TCP/IPv4).

Double-click on the selected item. In the window that opens, check the boxes Obtain an IP address automatically And Get DNS server address automatically.

Click OK and again OK.

By setting these settings this way, you will give Windows feature obtain the IP address and DNS server address from the router, modem or router. If your computer uses a static network address, then enter it in the previous step.

3. Clear DNS cache.

The DNS cache stores a table of correspondence between the site name and its IP address. Some viruses can replace this correspondence and thus block the opening of certain sites, as well as redirect users to various misleading web pages.

Like the following picture.

Enter in the field Open team cmd and press Enter. Will open command line. Type ipconfig /flushdns in it and press Enter.

4. Restore the LSP stack configuration.

LSP is a software service in the operating room Windows system, consisting of several layers. Each layer defines one program. All information requested from the Internet passes through this group of layers. Thus, if one of them, or a program that is bound to one of the layers, is incorrectly deleted, the entire LSP service will crash, resulting in the Internet connection becoming unavailable.

Windows XP, Vista, 7

Press the Windows key and the R(K) key on your keyboard at the same time. A window will open as in the following figure.

Enter in the field Open team cmd and press Enter.

Windows 8, 8.1, 10

Press the Windows key and the X(H) key on your keyboard at the same time. A menu will open as in the following figure.

Select an item Command Line (Administrator).

A command prompt will open. Type netsh winsock reset in it and press Enter.

Restart your computer.

5. Use AdwCleaner to remove malware components that block Internet access.

AdwCleaner is small free utility created by Xplode programmer. It will quickly scan your computer and remove malware components that may be blocking access to the Internet or specific sites.

Download, if the file download does not start automatically. After the program has finished downloading, run it. The main AdwCleaner window will open.

Click on the button Scan. This process can take up to several tens of minutes. When the scan is completed, you will see a list of detected malware components.

Click on the button Cleaning. AdwCleaner will begin cleaning your computer. To complete the process, you will need to restart your computer.

6. Use TDSSKiller to remove hidden Trojans and rootkits that block Internet access.

TDSSKiller is a free utility created by Kaspersky Lab. It can find and remove many different rootkits such as TDSS, Cidox, RLoader, Phanta, ZeroAccess, SST, Pihar, Sinowal, Cmoser and the like.

On the page that opens, click on the green button Download

Click on the button Start checking. The program will begin scanning your computer.

Wait until the scanning is completed and the detected rootkits are removed. When the program finishes, the computer must be restarted.

7. Use Malwarebytes Anti-malware for additional scanning.

Malwarebytes Anti-malware This is a great program created by Malwarebytes. It easily removes a wide variety of Trojans, rootkits, malicious and potentially unnecessary programs. The program is absolutely free for home use.

On the page that opens, click on the green button Download, if the file download does not start automatically. Run the downloaded file.

After the installation is complete, you will see the main screen of the program.

The program update procedure will start automatically. When it ends press the button Run scan. Malwarebytes Anti-malware will begin scanning your computer.

When scanning your computer is finished, Malwarebytes program Anti-malware will open a list of detected malware components.

Click on the button Delete selected to clean your computer from malware that may be blocking Internet access.

Conclusion

By following these instructions, you should be able to solve the problem with no Internet access. Unfortunately, there are variants of infection when these instructions may not help you, in this case, contact our.

To avoid infecting your computer in the future, please follow three small tips.
1. Always try to download programs only from official or trustworthy sites.
2. Keep anti-virus and anti-spyware programs updated to the latest versions. Also pay attention to what you have enabled automatic update Windows and all available updates are already installed. If you are not sure, then you need to visit the site Windows Update, where they will tell you how and what needs to be updated in Windows.
3. If you are using Java, Adobe Acrobat Reader, Adobe Flash Player, then be sure to update them on time.

Internet doesn't work.

The third case in a week - the Internet does not work. Gentlemen and ladies, friends, you can’t do this! You need to be very careful and careful about your computer, and even more so about the sites you visit. Any movie, song, picture, by definition, cannot have the extension song-title.exe! EXE- This executable file, and since almost all users working on their computer have the rights and authority of System Administrator, the file you launch runs with these rights. And the virus installs itself, with your “blessing”. Another question is that you do not see the extension of the file you downloaded, and indeed all the files in the system, and all because the owners of Windows, Microsoft, for some “good” reasons, hid them from you by default. That’s it – the Internet doesn’t work, or you have a full-screen banner with an offer to send money to some guy so that the computer can be unlocked. How to find a virus, I will return to this issue later, as well as about hidden file extensions.

File extensions are three letters at the end of the name, after a period. For example, Windows Notepad - notepad.exe, built into Windows graphic editor— mspaint.exe, or the cartoon “Masha and the Bear.avi”, song by A.B. Pugacheva – Iceberg.mp3. I propose to make all this visible. To do this, in the control panel, the panel can be accessed through the Button - Start -> Control Panel.

Now let's return to the question - about the Internet not working. All three cases are like a carbon copy. A cable from the provider comes to the apartment, is inserted into Wi-Fi router. The router distributes the Internet via DHCP (DHCP is a program in the router that assigns numbers to your pieces of hardware so you can remember how to access them), Wi-Fi and cable (patch cord) throughout the apartment.
The Internet does not work on one of the laptops, although in the PDA and in desktop computer There is internet. On that laptop where sites do not open, the icon in the lower right corner says that everything is fine - the Internet is connected. But as I already said, in reality it does not exist.

I’ll write a troubleshooting algorithm:
1. Launch the console (Start button -> Run -> cmd.exe). In the console we write ping ya.ru. If we see something like this.

This means that something is wrong with your Browser (Explorer, Opera, Mozilla, Google Chrome). We are looking for a new distribution and installing it again.

If we see such a picture.

This really means that the pings are not going through - and there is clearly no Internet. (You can use Windows command“tracert” to understand where things are lost)

2. Disable Windows Firewall and try the Internet.

3. Disable the Anti-Virus, or better yet, remove it. Let's try the Internet. We put another one and try it.

4. We try to connect the laptop to the router via a cable (patchcord).

If the Internet ping passes, then there is a problem with WiFi. We are trying to restart the router. If after a restart the Internet via Wi-Fi does not work again, we try to figure out the Wi-Fi module in the laptop. To do this, you need to turn on and off Wi-Fi, erase all existing connections in the Network Adapter Properties -> Wireless networks.
Reinstall drivers

(Delete old ones after downloading new ones from the module manufacturer).

If after these manipulations the Internet works for everyone except you.
5. Start fighting viruses:
6. First, look at what is loaded with the system, i.e. Autoload.

Launch via book. Start -> Run -> enter the command – msconfig -> Startup tab.

We turn off everything unnecessary, if you don’t know what, why, check with Internet Google Search.
If after disconnecting and rebooting there is no Internet, do the following.

7. Add a new user to the system, and give Administrator rights, reboot the system, and try to log in as a new user; if the Internet works, then your old user’s profile is corrupted or infected with a virus. (Next we deal with the found problem)

8. Further, more difficult, - Use the services of a pro.
Go to folder properties, through the control panel, and uncheck the boxes – Hide system files and folders, Hide Extensions for system files, select – Show hidden folders and files.

Let's go clean up user profiles. - Default User, All Users, and custom folders. We are looking for the extra. Clear Temp folders, Check startup folders. (I know what shouldn’t be there), the Internet can help you.

9. Further, more difficult, - Use the services of a pro.
Checking System registry— Launch through the book. Start -> Run -> enter the command – regedit. The Registry Editor will launch.

Be sure to check two branches:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

There shouldn't be anything superfluous in them. Google-Search to help

10. Clear “Temp” folders in C:\Documents and Settings\All Users\Application Data\TEMP\, C:\Documents and Settings\Default User\Local Settings\Temp\, C:\Windows\Temp, etc. p. – you can delete everything from there. What the system needs cannot be removed.

11. Through Total Commander check folders C:\RECYCLER\

12. Check for viruses. How to find a virus - first, look manually at C:\WINDOWS\SYSTEM32 for any clear files– csrcs.exe, aadrive32.exe or 22CC6C32.exe, etc.. Run the Anti-Virus for a full system scan. (in the settings you should say not to delete the files, but to move them to quarantine).

At this stage, in two cases the Internet via Wi-Fi worked. In the third case, I booted the system from a flash drive with WinPE_uVS _recSys, and found the missing ones.

Already 4 computers in a week had to be treated for the following misfortune: a machine with installed Windows XP and the free version of Avast Free antivirus stops seeing the local network. You open the connection status - it’s empty: no IP address, nothing. Network Services, such as DNS and DHCP also stop working. If you look in the logs, you will see the following messages: the DNS service cannot start due to a missing driver, etc. etc.

The following happened:

From December 5 to December 6, 2012 Avast! Free antivirus received an update in which, due to a developer error, the tcpip.sys file ( system file responsible for the local network and the TCP/IP protocol) was considered malicious and, accordingly, removed. In this case, the local network completely stops working on this PC.

How to restore the local network after Avast

I did the following: already tested on 4 machines, the method works 100%.

I haven’t used Avast for a long time, because I’m tired of it. Passes everything, including lockers, banners, worms. It’s better to pay for Kaspersky and be calm than to use free, but Imaginary protection.

Note: this problem appeared only in Russian Windows version XP

You did everything as expected, removed the virus, but now you understand that you cannot connect to the Internet. The following article will help you get your Internet settings back after virus software has deleted them.

1. Check your Web browser settings
The virus can redirect your browser to another host, so it’s worth checking your proxy server settings. You must make sure that your web browser is configured properly. Otherwise, you will receive an error message: “Internet Explorer cannot display this web page.” Follow these steps to fix the proxy error:

Open IE
. Open Internet Options
. Then select the Connections tab.
. Select Network Settings.
. Check Automatic detection parameters, uncheck the remaining boxes.

If your proxy server was configured differently, then after the changes described above and clicking the Apply button, the Internet connection should be restored. Just refresh the page by pressing F5.
If it doesn't help, read on.

2. WinSock recovery
Typically, damage to WinSock appears due to the removal of some viruses that change system settings related to the Internet connection. You will need to take several steps to restore your WinSock. (In Windows 7, you can click "diagnostics")

In Control Panel > Network Sharing Center and shared access> Change adapter settings. Right-click on the connection, and select "Diagnostics". This will help fix a damaged WinSock.
If this fails to restore WinSock or you have a different version of Windows, you will need to manually restore your network settings to resolve the problem. You need to remove the Winsock entries and then reinstall the TCP/IP protocol.
Reinstall WinSock by editing the registry
First you need to make a copy of the registry by creating a system restore point. Go to Start > Programs > Accessories > System Tools > System Restore. System will restore and create a restore point.
Then, open the registry editor, press WIN+R and type regedit in the dialog box. You should now be in the Registry Editor.
Warning: Running commands in the registry may damage your computer. Please use caution.
In the Registry Editor, locate the following keys and by right-clicking on the desired key, select delete:
1. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Winsock
2. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Winsock2

Restart your computer after you remove the WinSock keys.
If you do not restart your computer after you have removed the WinSock keys, next step will not work properly.
Step 2: Install TCP/IP
1. Right-click on the network adapter properties, and then click Properties.
2. Click Install.
3. Select Protocol, and then click Add.
4. Select Have from disk.
5. Specify the path: C:\Windows\inf, and then click OK.
6. From the list of available protocols, select Internet Protocol (TCP/IP), and then click OK.
7. Restart your computer.
The above steps should help you repair your browser and/or your damaged WinSock if you are unable to connect to the Internet after removing the virus. And you need further assistance, please contact our specialists.

Since December 5, 2012, the Internet was blocked for users of Russian operating systems Microsoft Windows XP. The problem arose due to an error by the antivirus company employees; a signature was released that damaged the TCP/IP protocol driver. On the 5th and 6th of December, all providers and services were “on their ears” - the Internet was lost for users Avast antivirus. A solution was found quickly, but the aftertaste from such work of the most popular antivirus remained.

« Avast blocked the Internet"- this problem is solved in several ways:

Solution #1 99% helps users restore Internet functionality (even if you have already uninstalled the antivirus itself - you can use Solution No. 1, just ignore the instructions on enabling/disabling Avast).
Download the file from the link: from here (mirror): http://depositfiles.com/files/jx9xqxtes

Instructions:
Download the avastfix.zip file from a friend/comrade/relative/neighbor who has Internet (see link above for XP SP3) onto your flash drive/CD-R;
Unpack the avastfix.zip archive on the faulty computer/laptop (right-click on the file - “extract all”);
Disable Avast: right-click on the Avast icon near the clock, select “manage avast screens”, then select “permanently disable”;
Run the file fixtcpip.bat, which is located inside the folder you unpacked, after which the computer will reboot;
Update Avast databases to latest version(double-click on the Avast icon near the clock, select “maintenance” - “update” - “update scanning and virus detection module”), turn on avast: right-click on the Avast icon near the clock, select “manage avast screens”, then select "turn on all screens"

ATTENTION! In very rare cases, you may have the “old” one installed. operating Windows XP with a second service pack (Windows XP SP2). If you do not know what version of the operating system XP SP2 or XP SP3 you have, then you can find out about this from the computer properties: click Start - right-click on “My Computer” - select “properties” and it will say which one you have Service Pack - 2 or 3.
Or download from here (mirror): http://depositfiles.com/files/a69gvaj6w

Solution #2
It is advised to first restore to the last working restore point, install Avast again and select “Ignore” when a message about this detection appears.

System Restore:
Unplug the cable with the Internet/USB modem until the system is restored. Start button - Accessories - System Tools - System Restore - select a restore point earlier than December 5 and perform a restore. After restoring the system, uninstall avast through “add or remove programs” in the control panel, insert the cable/modem.
Reinstall Avast:
How to properly perform a complete reinstallation of Avast! Free/Pro/IS

1. Download and save the full avast! installer to disk. Free/Pro/IS.
2. Download and save the utility on your desktop uninstall avast!
3. Delete in a standard way installed copy of avast! Free/Pro/IS
4. Restart your computer in safe mode.
5. Launch the avast! removal utility from the desktop. Free/Pro/IS (file aswclear.exe).
6. Specify the version of the program and the folder with it (if the program was not installed in the default folder).
7. Click the Uninstall button and wait for the uninstallation check to complete.
8. Close the uninstall utility window and agree to restart the computer in normal (normal) mode.
9. Install avast! Free/Pro/IS from the downloaded installer.
10. Restart your computer to complete the installation.

Note: Avast! Removal Utility Free/Pro/IS can be used without first uninstalling the program through the Panel Windows management. In this case, you must first disable the self-defense module: open the main program window => Settings => Troubleshooting => uncheck Enable the avast self-defense module!

If after installation the program does not ask for permission to perform a boot scan, it is recommended to assign it manually.

Don't forget to renew your registration free version or enter license information in paid.
Solution #3
Go to the folder C:/Windows/system32/dllcache, where it is located backup tcpip.sys and copy (but not move) it to C:/Windows/System32/drivers, then restart your computer. Or replace the file tcpip.sys with the file with installation disk(here he is, in zip archive).
Important: The tcpip.sys file must be added not to the %windows%/system32 folder, but to WINDOWS\system32\drivers

Solution #4
1. Boot into Safe Mode.
2. Start-run-regedit and delete 2 keys in the registry.

HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services/Winsock
HKEY_LOCAL_MACHINE/System/CurrentControlSet/Services/WinSock2

3. Go to the %windows%/inf folder, find the file Nettcpip.inf, open it, find the section and in the entry Characteristics = 0xa0 replace 0xa0 with 0x80
4. Go to Network connections, right-click on your network connection - Properties.
Open the General tab - click sequentially Install, Protocol and Add.
In the Select network protocols window, click Install from disk.
In the Copy files from disk window: enter C:/windows/inf and click OK.
Select Internet Protocol (TCP/IP) and click OK.
Return to the connection properties screen by local network, the Delete button is now active.
Now we remove Internet Protocol (TCP/IP).
It is advisable to replace the tcpip.sys file with the file from the installation disk (here it is, in a zip archive) before installing the protocol. You need to copy it to the %windows%/system32/dllcache and %windows%/system32 folders, then install the protocol.

Restart your computer

Go back to Network Connections and install Internet Protocol (TCP/IP) again using the Install from disk button and the path c:/windows/inf

And restart the computer again.
Solution 5
In some cases, if the three solutions to the problem did not help, you must also, in addition to tcpip.sys, copy the nettcpip.inf file from a working PC running XP to the windows/inf folder and repeat the steps from “Solution 4”.
Solution 6
Copy the “working” (see Solution 1.3) file tcpip.sys to c:/windows/system32/drivers
Then go to the device manager - “view” - “show hidden devices”. Select “Non-Plug and Play device drivers” - “Tcp/ip protocol driver” with the right “properties” button. Driver tab - startup, set the type to “system”. reboot the computer.
Solution 7
Use the TCPIP.Sys RestoreTool utility from UnHackMe. Link: http://www.greatis.net/tcpip_sys_restore.zip
Solution 8
Link to description of the process: http://itfound.ru/85-net-seti-avast-tcpip.html
Solution 9
Duplicates the solutions described here, but at the same time contains the tcpip.sys file for Windows 7. The problem in most cases affected Windows XP, but according to several users of the avast forum, cases of false positives were also possible on Windows 7. Link to the tcpip.sys file , if you cannot find it on another computer or as written in solution No. 3: http://avast-russia.com/files/tcpiprestore/tcpipWIN7.zip

After completing the steps described in the solutions to the problem, if avast again wants to delete this file, be sure to put this file in exceptions until you update your anti-virus databases to the latest version, which no longer contains the erroneous definition of the file as malicious.