[CentOS] Not firewall, but what?

[Jussi Hirvi]

Ok, thanks for ideas - many new things to test. So far no luck.

Too bad i don't have first-hand access to any of the client machines who 
*do* have this problem.

Next, I will go and switch the ethernet cable to a different slot on the 
router - kind of desperate, I know.

Some more details:
- this web server is a xen virtual guest system, with CentOS 5.4
- the problem surfaced yesterday morning (6th of May), after I had 
migrated all these web sites from an old Fedora box to this new CentOS 
system

Does the problem affect other xen systems on the same box? I haven't 
tested this yet (I cannot reproduce the error).

You could test yourself if you can see
	http://62.236.221.71 (the problem system)
	http://62.236.221.78 (another guest on the same xen host)

If someone *cannot* see the 1st one, then it would be interesting to 
know if (s)he can see the 2nd one or not.

- Jussi


On 6.5.2010 22.00, Benjamin Franz wrote:
> On 05/06/2010 11:42 AM, Ryan Manikowski wrote:
>>
>> Notice the op posted they get timeouts even when going directly to a
>> numerical address (if the apache server is configured to respond to
>> *:80 it should at least display something)
>>
>> Try using telnet from a client machine that can not connect.
>>
>> e.g. telnet host.name.here 80
>>
>> or
>>
>> telnet xx.xxx.xxx.xxx 80
>>
>> Try a few times and see if you're getting a timeout or if it connects
>> every time. Run tcpdump on the apache server while sending the
>> connection requests and see if the connection attempts show up at all.
>> If they do not, then it's a network problem.
>>
> Try running 'ab' (the apache bench tool - see 'man ab' for how to use
> it) against your server and see if you can provoke the timeouts. If you
> can, then you are probably not configured to handle many quick
> connections and should check (1) httpd.conf to make sure you don't have
> an excessively low setting for 'MaxClients' or (2) a too low setting for
> max open filehandles. Look in /etc/security/limits.conf - you should
> have a line reading something similar to:
>
>
> * - nofile 64000
>
>
> somewhere in it to raise the max number of open files. Busy web servers
> need lots of filehandles.
>
> --
> Benjamin Franz
>
> --
> Benjamin Franz
>
>
>
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-- 
Jussi Hirvi * Green Spot
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jussi.hirvi at greenspot.fi * http://www.greenspot.fi