I am presently running Ubuntu 12.04 and using Chrome/Firefox along with OpenDNS (have tried Google Public DNS as well as DNS of my ISP).
Suddenly, a lot of websites that I visit frequently don't load anymore. Some of them are imgur, yahoo, fed-sudoku, microsoft and addons page of firefox. I am sure there are many more that won't load.
I have Windows 7 in Dual-Boot and there are no problems whatsoever in opening these pages on Windows.
2 weeks back I installed Ubuntu 12.10. I faced this issue right-away on Ubuntu 12.10. I thought something must have went wrong with the installation, so I removed Ubuntu 12.10 and instead installed Lubuntu 12.10 on it. But the same issue persisted on Lubuntu as well. So, I tried opening these webpages in Live Environments (of Ubuntu 12.10, Lubuntu 12.10 and Ubuntu 12.04.1) from USB. The issue was there for Ubuntu 12.10 and Lubuntu 12.10. However, I was able to access these webpages from Ubuntu 12.04.1. So, I installed 12.04.1 on my HardDisk. Everything on 12.04 was fine till yesterday; but suddenly, these sites don't load anymore. All this while, Windows 7 in Dual-Boot works flawlessly.
Please help me resolve this issue.
(1) In response to Zhang's Answer to check
basic terminal commands - I have used both OpenDNS and GooglePublic DNS to test these commands (Restarted my PC in between). These are the terminal outputs while using OpenDNS and while using GooglePublicDNS.
(2) This is the result of
ifconfig - Pastebin Link.
(3) Thereafter I tried to use
wget to check if the problem was with the Browser. However, it didn't work for webpages which are not loading in my browser. This is the Pastebin Link showing it for Google(works) and Yahoo(doesn't work).
(4) Then followed the instructions listed at noobslab to
disable IPV6. Also, restarted my PC. However, it didn't help either.
(5) Then, I edited my Wired Connection through Network-Manager to
ignore IPV6. After that, I tried to open Yahoo in Browser - it did load the first time. However, when I tried again, it didn't load. Other problem sites didn't load at all.
(6) Again tried
wget. However, this time passed the argument
-4 to it; ie;
wget -4 www.yahoo.com. But once again, didn't get any response.
(7) Then, tried to fiddle with
MTU. Followed this link to check what is the maximum that I can set. For me, the maximum possible was 10324. Also tried other values like 1500, 1492, 1452 and 100. But this didn't help either.
Re-installed Ubuntu 12.04.1, wiping out the previous installation and as such all other changes. Also installed all the available updates. For the first half-an-hour, I was able to load all the webpages - including the ones which had problem. But lateron, I have the same issue as earlier - not able to load pages like yahoo, imgur, microsoft, fed-sudoku, etc.
(9) Question by laurent
From wget pastebin info in the question, the problem is not DNS as the
dig commands reach Yahoo's IP. This said, I don't know why nothing downloads with wget! Have you set a firewall? (you can check with
sudo iptables -L). In
ifconfig results, there are 2 interfaces, ppp0 and eth0. Which one should be used to connect to internet? Could you post the result of
route command? Obs: eth0 has no IPV4 address so I think it is not properly configured (how is
/etc/network/interfaces?) – laurent
Reply by me
Here is the Pastebin Link for terminal outputs of
sudo iptables -L ;
cat /etc/network/interfaces. I am not running any firewall. Its a clean install of Ubuntu 12.04.1. ppp0 is used to connect to the internet (this takes username and password which was given by my ISP) and eth0 is the Intel's OnBoard LAN which connects the modem through ethernet port.
(10) Tried to append
nameserver 18.104.22.168 line in
/etc/resolv.conf (since, I am using OpenDNS). But this didn't help (even after restart). So reverted the changes back. - [This is also a part of answer provided by laurent - it's required if I want to use OpenDNS].
- I have an ADSL modem (not a router) connected to the PC with an Ethernet Port. To connect to the internet, I have a DSL Connection. So, I use PPPOE to connect.
- Terminal Output for System Information
sudo lshw -C network;
ifconfig -a- Pastebin Link