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Old 02-03-2007, 12:11 AM   #1
Vundo Draxon
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Strange web browsing problem in Kubuntu


Kubuntu installed successfully on this computer. But when I tried going anywhere on the web using Konqueror, most of the time it would not load the page. I know it's not my connection going down because I was able to use Adept without any problems. So I used that to grab Firefox which did better but it still wouldn't load certain pages. It's weird because it's not always the same pages that refuse to load- for example, right now I'm obviously able to get onto linuxquestions.org, but google.ca won't load. Earlier the opposite was true.

I don't think my router (Linksys BEFSR41) is broken because there is a Windows XP box on the same router that has not experienced any problems. I'm not running a BitTorrent client or anything like that on any computers right now, and even when a Torrent app is running on the XP machine it does not seem to affect this problem one way or another.

So I used the Firefox I got out of Adept to install a newer version directly from mozilla.com- it still has the same problem. There appears to be no difference when I configure a manual IP vs. using DHCP. I can ping any website I want- even while it won't load in Firefox, it pings just fine. So I don't think it's the NIC because if it was then ping and Adept shouldn't be working perfectly, and it worked perfectly when this computer was also running XP. Disabling Java, Javascript, and all Firefox extensions doesn't have an effect one way or another. Tried disabling IPv6 support (Kubuntu help files suggest this as a fix for some DNS problems relating to Konqueror) and still no effect. Tried resetting the router- still no effect.

And finally, this is what I get when I run ifconfig:
Quote:
eth0 Link encap:Ethernet HWaddr 00:134:F4:5B:E7
inet addr:192.168.1.104 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::213:d4ff:fef4:5be7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:3959 errors:0 dropped:0 overruns:0 frame:0
TX packets:4077 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1787587 (1.7 MiB) TX bytes:375423 (366.6 KiB)
Interrupt:217 Base address:0x2000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:3 errors:0 dropped:0 overruns:0 frame:0
TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:172 (172.0 b) TX bytes:172 (172.0 b)
Does anyone recognize what would be going on here?
 
Old 02-03-2007, 12:28 AM   #2
Micro420
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post /etc/resolv.conf and `route`
 
Old 02-03-2007, 12:53 AM   #3
Vundo Draxon
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Quote:
Originally Posted by Micro420
post /etc/resolv.conf and `route`
resolv.conf looks like

nameserver xx.xx.xx.xx
nameserver xx.xx.xx.xx

Where the IP addresses correspond to my ISP. The numbers are the same in resolv.conf as they are when I look at the DNS servers listed when I run ipconfig /all from a cmd prompt on the working XP machine.

What do you mean by `route`?
 
Old 02-03-2007, 01:16 AM   #4
Micro420
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type route at the command line. Just want to see if there's anything strange happening with how packets are being routed.

Also, do a tracert and ping -c 100 to a website and see if there are any packet losses happening.

Last edited by Micro420; 02-03-2007 at 01:18 AM.
 
Old 02-03-2007, 01:51 AM   #5
Vundo Draxon
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Quote:
Originally Posted by Micro420
type route at the command line. Just want to see if there's anything strange happening with how packets are being routed.

Also, do a tracert and ping -c 100 to a website and see if there are any packet losses happening.
Okay, here's route:
Quote:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
I don't know if that's normal or not.

As I said (or at least meant to say) before, ping never reports any losses. However when I run a tracepath on google.ca it won't go past my ISP before getting no reply. This is weird because I can still ping google.ca from this and the XP machine, and right now it even loads in Firefox!
 
Old 02-03-2007, 01:57 AM   #6
Micro420
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Your routing table looks fine.

Check your Firefox and Konqueror setting to make sure that they aren't using a proxy server or anything like that. Also, I know this is dumb, but try rebooting your Linux box. Try switching to a different physical port on your router? Check network cable??

You could also try browsing the internet using the w3m browser. Try this at the terminal:

Code:
w3m google.ca
Does it browse okay with text based?

Other than that, I don't have any other ideas on why your Windows machine works fine on the internet but your Linux doesn't.

Last edited by Micro420; 02-03-2007 at 01:59 AM.
 
Old 02-03-2007, 02:06 AM   #7
Vundo Draxon
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Quote:
Originally Posted by Micro420
Check your Firefox and Konqueror setting to make sure that they aren't using a proxy server or anything like that.
Nope. I've tried it with no proxy and with autodetect- doesn't make a difference either way.

Quote:
Originally Posted by Micro420
Also, I know this is dumb, but try rebooting your Linux box.
Sounds perfectly reasonable- but unfortunately doesn't help.

Quote:
Originally Posted by Micro420
Try switching to a different physical port on your router? Check network cable?? Other than that, I don't have any other ideas on why your Windows machine works fine on the internet but your Linux doesn't.
I didn't try this machine on another port/cable yet, but a different computer can use the same cable on the same port while running Puppy. So I have my doubts that it's a physical cable/port problem, but I might consider trying this box on a totally different network just for the hell of it.

Other than that, I'm totally stumped.
 
Old 02-03-2007, 02:48 AM   #8
Vundo Draxon
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Quote:
Originally Posted by Micro420
You could also try browsing the internet using the w3m browser. Try this at the terminal:

Code:
w3m google.ca
Does it browse okay with text based?
w3m works with websites that also work in Firefox, but hangs at "Opening Socket..." for those that do not load in Firefox.
 
Old 02-03-2007, 04:04 AM   #9
Vundo Draxon
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Hmm... I just tried google.ca and could not connect via Firefox. So I quickly opened up a console and ran a tracepath on google.ca:
Quote:
1: 192.168.1.104 (192.168.1.104) 0.121ms pmtu 1500
1: no reply
2: no reply
And so forth. So then I try it on sites that do load in Firefox, and keep getting the same thing. Of course I can still ping the website without any problems.
 
Old 02-03-2007, 01:03 PM   #10
archtoad6
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Well stated.
  • For the record: which vers. of Ubuntu & KDE?
  • What is tracepath? -- I don't have it on SimplyMEPIS 3.3.2
  • When you ran tracepath after the posted Firefox google.ca failure, did you also run
    ping -c100 google.ca & traceroute google.ca?
  • Did google.ca fail in w3c & Konqueror, too?
  • It's a longshot, but re-boot the router.
  • Are you keeping notes or a log of the incidents?
  • Have you developed a "protocol" of tests you are running every time this happens?
 
Old 02-03-2007, 02:43 PM   #11
Micro420
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Quote:
Originally Posted by Vundo Draxon
Hmm... I just tried google.ca and could not connect via Firefox. So I quickly opened up a console and ran a tracepath on google.ca:

And so forth. So then I try it on sites that do load in Firefox, and keep getting the same thing. Of course I can still ping the website without any problems.
It seems like it can't even get out of your router. It's not even sending it to the ISP's routers. Did you set up any firewalls on Kubuntu? what is the output of
Code:
sudo iptables -L
Good checklist, Archtoad6!

Last edited by Micro420; 02-03-2007 at 02:45 PM.
 
Old 02-03-2007, 09:44 PM   #12
Vundo Draxon
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Quote:
Originally Posted by Micro420
what is the output of
Code:
sudo iptables -L
As follows:
Quote:
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Quote:
Originally Posted by archtoad6
[list][*] For the record: which vers. of Ubuntu & KDE?
Installed from a Kubuntu 6.06 disc. KDE version 3.4 (I think)

Quote:
Originally Posted by archtoad6
[list] [*] What is tracepath? -- I don't have it on SimplyMEPIS 3.3.2
And I don't have traceroute. It seems to do something very similar to the tracert command from DOS/Windows, as I would assume traceroute also does.

Quote:
Originally Posted by archtoad6
[list][*] When you ran tracepath after the posted Firefox google.ca failure, did you also run
ping -c100 google.ca & traceroute google.ca?
Not traceroute as that is not a recognized command on this system, but yes I ran a ping right away and it didn't report any losses, as usual.

Quote:
Originally Posted by archtoad6
[list][*] Did google.ca fail in w3c & Konqueror, too?
Yes- when a site fails in one it fails in all of them. Then when it's working again it works for all browsers.

Quote:
Originally Posted by archtoad6
[list][*] It's a longshot, but re-boot the router.
Tried that, but it does not appear to have changed anything.

Quote:
Originally Posted by archtoad6
  • Are you keeping notes or a log of the incidents?
  • Not outside of what I've been posting in this thread.


    Quote:
    Originally Posted by archtoad6
  • Have you developed a "protocol" of tests you are running every time this happens?
Not much of a formal protocol, but I always open up a couple tabs right away and test with some reliable sites to see if it's actually the connection problem or if it's just one site being slow (sometimes that happens). If it does affect multiple sites I try restarting the browser, then disabling/enabling the network connection. Beyond that, it's a matter of coming back half an hour later and trying the sites again.



It was suggested to me that I try looking at changing the MTU value for the interface I am using- I'm working on that right now and it seems at least for the moment that I'm getting fewer problems.
 
Old 02-05-2007, 11:18 AM   #13
archtoad6
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To summarize, the problem is:
  • Intermittent
  • Confined to one computer & distro -- posts 1 & 7
  • Confined to web browsing -- posts 1, 5, 9
  • Affecting all browsers tried -- post 12
  • Not in the router -- post 12

At this point I would consider sniffing the connection at various points. Of course, I have the equipment -- hub between my firewall & aDSL "modem", plenty of spare NIC's, & at least 1 extra GNU/Linux box to do the sniffing. Your situation may not be so conducive.

Does anyone else have any easier ideas to try 1st?
 
Old 02-07-2007, 01:21 AM   #14
Vundo Draxon
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Quote:
Originally Posted by archtoad6
To summarize, the problem is:
  • Intermittent
  • Confined to one computer & distro -- posts 1 & 7
  • Confined to web browsing -- posts 1, 5, 9
  • Affecting all browsers tried -- post 12
  • Not in the router -- post 12

At this point I would consider sniffing the connection at various points. Of course, I have the equipment -- hub between my firewall & aDSL "modem", plenty of spare NIC's, & at least 1 extra GNU/Linux box to do the sniffing. Your situation may not be so conducive.

Does anyone else have any easier ideas to try 1st?
That's a fair summary.

And I do have some spare equipment- just no clue how to do sniffing. Would you happen to have a link to some kind of tutorial?

And another thing... this is an integrated NIC in the Kubuntu box. Maybe the problem is that Kubuntu isn't handling that as well as Windows did. Can I just throw in another NIC into an expansion slot, or do I have to figure out how to disable the integrated first?
 
Old 02-08-2007, 05:59 AM   #15
archtoad6
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I think you could start w/ no add'l equip. at all. Just install ethereal, now called wireshark, & have it report on the box having the problem. This might show if the HTML packets are even leaving for the LAN.

Phase 2 would be to put in a 2nd NIC & use it to sniff other points on the packets' path through your LAN to the 'Net.

Before you use the new NIC for sniffing, you might just try connecting through it, this might solve the problem, although it might not explain it.

In dealing w/ 2 NIC's in 1 box, you need to know their MAC addresses before you start. Probably the easiest way to do this is to run ifconfig before you put the 2nd 1 in & record the MAC address of the 1st. Later, the new MAC must be that of the add'l card.

One thing to remember, you will need a hub, NOT a switch to insert at the different "sniff points". Hubs allow this kind of eavesdropping, switches hide the traffic on the different physical ports from each other.

I haven't used wireshark/ethereal for several years, but it didn't seem hard to learn the basics at that time.

An alternative to putting a 2nd NIC in the subject box is to install wireshark on a different computer (presumably a GNU/Linux machine) & use it w/ the hub to do the sniffing.

Here is the topology of my LAN:
Code:
0.   'Net
       |
1.   Modem
       |
2.    Hub       (A)
       |
3.  Firewall (& router)
    (SmoothWall Express)
       |
4.  Hub/Switch  (B)
    Combination
       |
5.  Computers   (C)
Because both 2 & 4 are hubs, I can sniff at A & B easily. I can also monitor any Linux machine internally. (I haven't even looked for a "Winders" sniffer.)

Your set up is probably simpler:
'Net--Modem--Router (w/ built-in switch)--Computers

I think I am getting ahead of myself, it may not have to be this complicated. In fact, I almost greyed out everything from here back to my 1st paragraph.

As I said at the beginning, start by installing wireshark (I assume you won't find it called ethereal any more). Read its manual/help(/tutorials?) & get comfortable w/ it. See what it shows -- are your browsing packets even getting out the existing NIC. If they are, even when you're in the middle of an episode of the problem, then consider what the next step should be.
 
  


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