Strangest problem while connecting to the internet I ever seen
 

Hello gentelmen,
This problem is the strangest issue I ever seen during my working in computer field for nearly 6 years.

let me describe the scenario :
I had an ubuntu 10.4 box, I used it mainly for programming, virtualization & other stuff.
I've installed this box about 1 month ago, working on it everyday.
About 2 days ago problem appeared when I just opened up firefox for cheking my E-Mail.
I typed : mail.yahoo.com & nothing appeared & I just seen the famous firefox page when a networking problem is around .
I just wondered and checked the connectivity & the wire itself, but find no problem around them, while playing with firefox I just had a turned on virtualBox machine (Windows XP service Pack 3), I just checked the internet within vm & working fine, I checked my e-mail from vm (windows xp), I thought restarting the system might help to solve the problem but damn, problem didn't solved & still arounds ...
Well, I searched through websites dedicated to linux networking & forums that might help, I did anything that faced to my brain , follow another people recipes but problem did't solved for about 3 days !
Playing with primary & alternative dns didn't help, I did my best about solving the problem, disabling ipv6 from both linux networking settings & firefox itself didn't help also .
After that, I thought reinstalling the linux might help to solving the problem, but install a new version of ubuntu, 10.10, I tried it, install it but the holyshit problem still arounds !
I think this might be a bug on ubuntu distro, I tried Mint 10 & the same problem, reinstalling x64 version of fedora core & the same problem ... damn it !
It's interesting that the same settings for TD-8101G TP-Link working fine for my Windows XP, Windows 7 x64 & the problem is arounds just for my linux distros .
As I said I checked the internet for the problem & found nothing workable for me.
I thought it's better to describe the problem & maybe another people faced with that problem .
any help would be appreciated, I just will going crazy if this problem not solve anymore because microsoft windows is a fool os for me .

Thanks .

initially I'm tempted to suspect ipv6. http://support.mozilla.com/en-US/kb/...programs%20can

I didn't think like you, I described that I disabled it without any success .

Alright, so let me get this straight, the VM running inside ubuntu (or linux) can access the net no problem, ubuntu (or linux) can not.

So how are things configured?

Did this start when you added the VM?

Is the VM NATd or Bridged with your NIC?

If applicable, can you ping other systems on your LAN?

Can you ping by DNS to the net?

Can you ping via IP to the net?

Is firefox set up to use a Proxy Server?

You have described a very general problem, so we will need to do some troubleshooting to narrow down what exactly is happening.

Hi ,
Nope, Almost everyday I used virtualBox & I think there's no concern about it's existence.

Both of them could be used, I tested out both, with no problem, & the last time I used it, it was bridge .

yes, of course .

Every ping I issued was fine, but almost slow .

Nope, I'm using vpn as my primary privacy tool .

Thanks .

yeah you did mention ipv6. my bad. So you need to get more local that vm's and things. do other browsers work on the linux box? what about curl? fire up wireshark and use Firefox, what traffic is resulting from that?

If DNS is slow, whats in your /etc/resolv.conf? Is it possible that the first entries are failing and allowing FireFox to timeout on DNS??

Is the box running a DNS server or Forwarder?

Will Firefox load a page by IP Address? (I am guessing that it will)

Try to load google.com by IP
74.125.225.19
74.125.225.18
74.125.225.20
74.125.225.17
74.125.225.16

@ acid_kewpie : Hi, in this time it's no possible for me to download other softwares directly from the internet on linux, because of the problem, but I will download a packet sniffer as you said and monitor it & of course I will test other browsers & put the result back to you .

@ never say never : thanks for your response, the only entry I have on my linux machines located in /etc/resolv.conf is nameserver 192.168.1.1 . I changed it many time manually with OpenDNS entries, but nothing changed and still I have the problem .
also this is the connection information :


seems the default route & primary DNS are same, but I think there's no problem with these entries .

about browsing pages with ip address, yes , you're right, seems it's working fine with ip addressing , without using dns name, but for some websites it's fine .

Hi again Gentelmen,
I think I discovered the problem .
I called my ISP service, they said they had some internet censorship and there are some problems around the whole internet in Iran, like always, shit !
The supporter said me, type any websites you want with domain .ir, I typed tabnak.ir and some other .ir websites & they worked fine , but still I can't understand what's the difference between linux & Windows at this point .
Also, another important point : because of government limitations on internet I always using VPN, but my VPN service finished for this month & I think if I recharge my VPN account, the problem might solve .
any feedback ?

thanks .

Hi again people .
I want to mention please set the flag of this topic to SOLVED.
I did nothing special with my linux boxes, however I just recharge my new vpn account, and with VPN there's no problem arounds.
Thanks for all guide & advices .

regards.