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I was over at a friend's house and her roommate complained of computer troubles. A standard Dell laptop running Vista. When plugged into the internet (no router) both IE and Firefox would refuse to work. However, a simple

ping www.google.com

worked flawlessly. Any ideas?

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What about other services (E-Mail, ICQ, FTP, ssh, etc.)? –  balpha Aug 18 '09 at 10:48
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9 Answers

First thing to check is the proxy configuration of both web browsers. In IE this can be found under "Tools", "Options", "Connections" and "LAN Settings". If anything is ticked in there, try removing it (or double check the settings are correct for your internet connection).

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Third step after successful pinging a machine and having already checked the proxy settings of the browser (don't forget to check how they are set at the machine where it does work) would be to actually trying to connect on the correct port with telnet. You don't need to understand the protocol, usually it's enough to see whether a connection can be established or not.

From the command line, type

telnet www.google.com 80

Where 'www.google.com' is the name of the site you want to connect to and '80' is the port - I assume you're trying to access the web interface, so that would be 80. Expect one of:

Connecting to www.google.com...Could not open connection to the host, on port 80: Connect failed

Means the connection couldn't be made by any reasons: the port might be closed, a firewall might be blocking the request, the host name might not be found, or the remote machine not be reachable. Yeah, rather unspecific, that's why you try the ping first.

If the screen blanks (WinXP telnet.exe does this, Linux does not) and it seems like you can enter something (cursor moves), the connection seems to be fine. Don't worry if you don't see your cursor anymore, don't see what you type or some garbagge is printed - just close the window.

If the connection doesn't work, look for personal firewalls.

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In this case it's almost always the firewall that's blocking them. It most often happens after a security update that the firewall automatically blocks them or the user gets notified and blocks them.

Check the list of allowed/blocked programs in your software firewall and make sure that both ie and firefox are allowed.

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A firewall suddenly blocking outgoing connections (but not when using the command prompt) after some operating system update? You may be right, but I've never heard of that before. Did you ever encounter that yourself? –  Arjan Aug 18 '09 at 11:02
    
all the time, I work in support and that's the most common failure mode for customers internet connection. Often happens after ms patch tuesday that IE gets blocked :) –  Pär Björklund Aug 18 '09 at 11:21
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I have quite often seen this because the ISP have blocked webtraffic due to suspicious activity. Usually from malware/viruses on the users computer.

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So, test with another computer on that same connection. –  Arjan Aug 18 '09 at 11:02
    
If the ISP blocked, another machine at the same place will probably have the same problem... –  bortzmeyer Oct 1 '09 at 12:00
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@Zefiro above wrote good solution but it could be a bit better formulated. From above description (ping is working, web browsing is not working), following can be concluded:

  1. DNS is working (resolving of www.google.com to 208.117.229.182 or something similar)
  2. your PC is connected to internet

To reconfirm above, try pinging some other addresses, like ping superuser.com

If it works, then above two conclusions are correct. Then try @Zefiro's solution from command prompt: telnet superuser.com 80, and if you get black screen, that means http is working using telnet - that means your web browsers are blocked somehow, not http protocol with firewall. In that case check proxy settings (you need no proxy if direct telnet connection is working). If that doesn't help, try disabling firewall(s).

If above telnet test fails, then you can be pretty sure that problem is with firewall, disable it.

Of course, some virus could do something like that but it is unlikely, as viruses mostly tend to not change behaviour of your PC too much to be able to do evil things on your PC as long as possible.

With current information nobody can give more detailed answer, as to detail here how to disable 10 or 20 most often used Windows firewalls would be overkill.

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Firewall, antivirus, proxy settings, temporary internet files, etc, all can cause this kind of problem.

The quickest and easiest thing to do is reset Internet Explorer's settings.

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What worked for me in this case was running System File Checker

sfc /scannow

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What worked for me after 2 days of war with my pc was do uninstall the zonealarm. even though i didn't see it running in the processes (in the windows tasks manager) is blocked my browsers from seeing web pages, while ping www.google.com worked well.

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My Solution was:

plug the cable into another ROUTER PORT (if needed, Restart PC and Router)

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