[Server-devel] Web Caching Issues

[John Watlington]

On Mar 16, 2010, at 11:30 PM, Andra DuPont wrote:

> With the internet disconnected, my web browser just says it can't display anything
> because it is not connected to the internet. When I plug the DSL modem back into
> eth0 on the XS, all is fine.
> 
> How do I turn on DNS server logging?

You increment the trace level using the remote name daemon controller:
Something like:
sudo rndc trace 5

> Andy
> 
> On Mar 16, 2010, at 11:06 PM, John Watlington wrote:
> 
>> 
>> When you turn on offline mode, you are just handling
>> the HTTP requests.   There are other network operations
>> which have to happen before hand which probably aren't
>> being "offlined" properly.
>> 
>> What happens to DNS in the offline scenario ?  If your clients
>> are all properly pointed at the school server's DNS server,
>> and the entries aren't timing out, it might resolve properly.
>> Otherwise, the HTTP request will never be made.
>> 
>> Once you switch to offline mode, what does squid's access
>> log indicate ?   error log ?   You can turn on logging on the
>> DNS server and see if name resolution is being requested.
>> 
>> Cheers,
>> wad
>> 
>> On Mar 16, 2010, at 10:38 PM, Andra DuPont wrote:
>> 
>>> I have reconfigured my server so that my internet connection goes straight from my DSL modem to eth0 on the XS. This did not solve the problem (web chaching not working), but it eliminated Windows 7 Firewall as the cause. I have several computer connected both wired and wirelessly to the AP on eth1 of the XS. They can access both the schoolserver and the internet (so long as the internet is active on eth0 of XS). When I disconnect the internet service, the AP computers can still get to the schoolserver, but not to the external web pages that should have been cached from the internet.
>>> 
>>> Internet service at the remote village in Kenya where this server will be installed is poor and intermittent. It is therefore critical to be able to cache whatever content does come in. I am also considering some modifications to the Squid.conf file to accommodate turning the offline_mode on and off depending on the status of the internet connection. See this article for the concept and proposed solution.
>> 
>> See what article ?
>> 
>>> I have tried turning offline_mode "on" after caching a bunch of web pages to see what would happen. When I disconnected the internet service to eth0 on the XS, external web service stopped. In other words, the server would not serve up the cached material, or at least that was my conclusion.
>>> 
>>> Does anyone have a simple diagnostic approach to this problem. I am new to linux, OLPC and XS, so it's like drinking from a fire hose right now. Can someone point me in the right direction.
>>> 
>>> On Mar 16, 2010, at 2:51 PM, Andra DuPont wrote:
>>> 
>>>> I have set up an XS server at my home to become familiar with it so I can help an installation in Asilong, Kenya. There server has never been used as no one there understands it.
>>>> 
>>>> My server is running the latest XS (0.6) and in order to simulate the situation in Asilong, the server is connected to the internet on eth0 from a PC running Windows 7. The PC is connected wirelessly to my home router, and that connection is bridged on the PC to its ethernet port which is then connected to the XS-eth0. The XS-eth1 is connected to a wireless AP and I'm testing performance of the server by connecting an iMac to the AP. The iMac can log into the Schoolserver, and can also access the internet. So far so good.
>>>> 
>>>> I have enabled squid on my server, but web caching does not seem to be working. I'm wondering if feeding my internet connection to the server from a bridged connection on my Windows 7 computer with Windows Firewall running is interfering with some of the dns information on the cache.
>>>> 
>>>> "Revisited" pages don't load faster (if I clear the cache on the connected iMac), and if I disconnect the eth0 internet feed, the server is unable to retrieve anything external, even material that should be cached.
>>>> 
>>>> I am working now on setting up the forwarders correctly in the named-xs.conf.in file, and also playing with the "offline_mode on" setting in the squid-xs.conf file to see what affect it has.
>>>> 
>>>> Any thoughts from the team?
>>>> 
>>>> Andy DuPont
>>> 
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>> 
> 
>