[Gllug] NTL + Wireless network problems

Admin admin at catnip.co.uk
Tue Jan 9 20:34:11 UTC 2007


John Hearns wrote:
> I have no experience of NTL lines etc. etc.
>
> As other people have said what does your daughter mean by "slow"?
Worse than slow dialup - minutes to load a page.
>
> First thing to think about is name resolution.
> Maybe with the original Netgear access point the box was used as a DNS 
> server and it is still in resolv.conf ???
> Look at /etc/resolv.conf and see if (maybe) your original wireless 
> access point is first in the list of DNS servers, followed by the NTL 
> ones. Ping the NTL DNS servers, in case one of them isn't active.
> You should have a working DNS server as the first entry.
>
>
> tcpdump -i ethXX   and do some web browsing/send email
>
> Install wireshark and look at the traffic on the network interface again
> http://www.wireshark.org/
> (what used to be called ethereal)
>
> As you say, there are online "test my connection speed" pages.
> Or if you have access to another server,
> you could install netperf on it and use that for performance 
> measurements:
> http://packages.debian.org/unstable/net/netperf
>
> (Disclaimer - I use netperf for LAN measurements, never over a WAN,
> but it should work, firewalling issues obviously coming into play)
>
>
> Also worth installing ntop to have a look at what traffic is coming 
> into/out of the box, but that won't do any diagnosis of bandwidth for 
> you. More for interest.
> http://www.ntop.org/
> Also etherape for traffic monitoring
> http://etherape.sourceforge.net/
>
First thanks to everyone who replied to this.

John, you are right, the problem appears to be DNS based.

I had my daughter use the external OpenDNS servers by adding the line

prepend domain-name-servers 208.67.222.222, 208.67.220.220;

to /etc/dhcp3/dhclient.conf so that those nameservers are tried first, 
before the one in the wireless router (192.168.2.1)
(the addresses are added to the top of /etc/resolv.conf when dhcp 
starts) and now the machine works normally.

I can only assume the router is struggling to redirect DNS requests back 
to NTL...

And yes, I hear some of the Windows users are 'fiddling with the network 
settings'  :-)

I'll write this up eventually on 
http://www.catnip.co.uk/projects/gnu/linux/usw/

Best Regards,

Pete.


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