[CentOS] Network Connection Card Problem?

On 9/11/07, Jun Salen <nokijun at yahoo.com> wrote:
> >Hi List,
> >
> >My Mail/Proxy server has from time to time refuse to
> >accept accept network connection. If I restart the
> >network service, the service will again start to
> >accept connection but after some time will again
> >refuse connection. I use CentOS 4.5 with Squid,
> >DansGuardian, Postfix. Please can someone point me
> >what are the possible cause of this. Thank you.
>
> In addition to my posting above. When I make ping to
> other machine from the server, the server will again
> restore and accept connection. This is weird, so my
> temporary solution is to let the server continually
> ping other machine. Please help. Thanks again.
>

Ping is a very cheap and acceptable solution !

Anyway you'r certainly curious about the problem :-)
This is a problem about ARP request.
Maybe another machine with low activity share the same IP or your swith/hub
is badly configured !
You can use arping to detect any device with the same IP and tcpdump
to look for arp request."arp -an"  will show you the arp table.

Regards

> junji
> aisalen.wordpress.com
> Linux Registered User #253162
>
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Alain Spineux
aspineux gmail com
May the sources be with you