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Old 12-10-2006, 07:16 PM   #1
abrahammer
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adsl internet problem in ubuntu 6.06, k7


hi, i used pppoeconf to configure my internet connection and it worked to connect my pc but after like 15 minutes i can't surf the web with mozilla-firefox anymore. the plog command won't show any info after that, but if i'm connected to msn for example i remain so and can still send messages. it i use the command ifconfig before connecting, i get lo, eth0 and eth1, but if i do it after connecting i get, lo, eth0, eth1, ppp0. It seems that the ppp0 screws up after 15 minutes, because it isn't configured but if i try to configure it System->Administation->Network, i must put a dial-in number, which i don't use because its an adsl connection.

WTF
 
Old 12-10-2006, 09:24 PM   #2
sadiqdm
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What is your network config? ADSL combined modem/router or ADSL modem with external hub or router.

I have ADSL with a Linksys router. The router is set to provide connections with DHCP. All I did when installing Linux (Suse 10.1 or Kubuntu 6.10) was tell it to use DHCP to connect. Never had to touch anything after that, except on my laptop which has both ethernet & wifi, and took a bit of juggling of boot priority (on Suse 10.1 using YaST) so now it will look for a known wifi network and connect to that, or to ethernet if you plug in the cable. Unplug the cable and it looks for the wifi.

I expect that you could do the same if your ADSL modem supports DHCP.
 
Old 12-10-2006, 10:19 PM   #3
abrahammer
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i have an adsl modem with an external router and i configured the ethernet (eth1) for dhcp and it works so i guess it supports dhcp, the problem is that i can't surf even though i think i'm still connected
 
Old 12-10-2006, 10:42 PM   #4
sadiqdm
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OK. This sounds like a problem my Mum had. She has cable broadband, and I added a router so she could use her laptop with a wireless connection. The cable broadband box is more like a phone line modem, than an ADSL modem. In the end I found I had been set-up it so it cloned the MAC address of her old desktop for which it was first set-up. You may find that your ISP's authorisation routine has this address. If your ADSL box has a web access, then you will find somewhere to set it's MAC address. This is a unique hardware address, which is built into network adapters chipsets.

If you type ifconfig at the command line it will tell you the MAC of your PC.
 
Old 12-10-2006, 11:06 PM   #5
Wim Sturkenboom
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I doubt very much that it is pppoe that screws up as your msn is still working (if I understand you correctly).
What are the symptoms in your browser? Can't find server or something else?

To check if you're still connected, you can try to e.g. ping www.google.com.
Code:
wim@internet-desktop:~$ ping www.google.com
PING www.l.google.com (216.239.59.103) 56(84) bytes of data.

--- www.l.google.com ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 999ms
In above example you can see that the name gets translated to an ip-address. So your connection still works. 0 packets received is the result of iptables that blocks icmp (ping).
If you don't get an ip-address, the problem lays with DNS.

Do you start iptables (the firewall)? You can check this with sudo iptables -L -n. If you see three lines like
Code:
Chain OUTPUT (policy ACCEPT)
, it's not blocking anything. If you see a whole list of things and 'accept' has changed to 'drop', it's blocking.

Does your IP address change during your session? Check ppp0 in ifconfig after you've connected and check it when you can't surf.
 
Old 12-11-2006, 05:39 PM   #6
abrahammer
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iptables is started, i got the whole list. i think i configured it with firestarter. sadiqdm was right my adsl router is more like a phone line router (english is not my native language so i don't know to explain some things) but i can't find the MAC of the pc he was talking about in ifconfig. i haven't tried the ping yet.

when i use the command pppd i get this message:
pppd: The remote system is required to authenticate itself
pppd: but I couldn't find any suitable secret (password) for it to use to do so.pppd: (None of the available passwords would let it use an IP address.)

does this matter?

now the plog command won't work, why does it work only sometimes?

now it happened, i can't surf the web anymore, i get "server not found" and when i ping www.google.cl i get the unknown host message. then i use killall pppd and then pon dsl-provider again. now if i put ifconfig i get a different inet addr for ppp0 and can surf with mozilla-firefox again

how do i see my DNS? what is theDNS?

Last edited by abrahammer; 12-11-2006 at 06:19 PM.
 
Old 12-12-2006, 02:28 PM   #7
Wim Sturkenboom
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DNS stands for domain name server and translates names to ip-addresses.
Although I don't know how msn exactly works, I assume that once your logged in it works on ip-addresses and not on names. That will explain why it keeps on working while you can no longer surf.

After you have established your connection, check either the output of plog or the network administration tool (tab DNS). It will give you the ip-addresses of the dns servers; write them down.

When something goes wrong the next time, ping those addresses and try to access google in the webbrowser using the ip-address that you've found when pinging google with a working connection.
Give us feedback on the results.

PS
plog only shows recent information regarding your ppp configuration if you use the default ubuntu configuration. You can change this but I have not tried that yet and can not advice on it. Read man plog.
So you will only get something immediately after you've established your connection or when you use poff, at least that's my experience.
 
Old 12-13-2006, 11:45 AM   #8
abrahammer
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ok, i got the dns with plog and then did ping www.google.cl and it worked. i saved that ip and when i couldn't surf anymore i used the ip on the browser and it worked i could surf again, so it is a dns problem. then checked the resolv.conf and the ip's there were the same that i had seen with the plog command, so the problem isn't in that file
 
Old 12-14-2006, 12:35 AM   #9
Wim Sturkenboom
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Does your firewall (if you have one running) block icmp (ping) requests or do you get output like (this one taken from a windows box)
Code:
C:\Documents and Settings\wsturken>ping btd-techweb01

Pinging btd-techweb01.mca.naspers.dom [172.31.212.190] with 32 bytes of data:

Reply from 172.31.212.190: bytes=32 time<10ms TTL=64
Reply from 172.31.212.190: bytes=32 time<10ms TTL=64
Reply from 172.31.212.190: bytes=32 time<10ms TTL=64
Reply from 172.31.212.190: bytes=32 time<10ms TTL=64

Ping statistics for 172.31.212.190:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum =  0ms, Average =  0ms

C:\Documents and Settings\wsturken>
If you get that, your firewall does not block ping. In that case you can ping your DNS servers by ip. Interesting part is the time.

Try this while your connection is working (that's your reference to see if the approach works) and again when surfing does not work; do you get similar results (times are approx. the same)?

If you get timeouts or significantly different times, the problem is more-than-likely with your isp. If your results in both cases are more-or-less the same, the problem is definitely on your site.

Unfortunately I'm now at the end of my network debugging knowledge, so I'm probably not able to help you further.

PS If you have a firewall running, you can turn it off when the problem starts. It might be that a rule gets changed somewhere (although not likely) and see if you can surf.

Last edited by Wim Sturkenboom; 12-14-2006 at 12:37 AM.
 
  


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