[CentOS] Centos machine sometimes unreachable

Wed Aug 22 13:20:45 UTC 2012
Giles Coochey <giles at coochey.net>

On 22/08/2012 14:01, Richard Reina wrote:
> I have a simple perl script that every few hours pings the handful of
> machines on my LAN. Lately I've sometimes been getting
>
> ping of 192.168.0.1 succeeded
> ping of 192.168.0.7 succeeded
> ping of 192.168.0.5 FAILED
> ping of 192.168.0.6 succeeded
> ping of 192.168.0.9 succeeded
>
>    This machine in question has been running Centos faithfully for about six
> years and no recent changes to it have been made. When I try and ping the
> machine manually it works.   /var/og/messages does not seem irregular. Does
> anyone know know what might be the problem or what else I might check?
>
>
>
I had this problem in the past and found that it seemed to be due to 
iCMP rate limiting. We were pinging a lot of hosts from the monitoring 
system, however... But you might want to investigate here: 
http://www.kernel.org/doc/man-pages/online/pages/man7/icmp.7.html

-- 
Regards,

Giles Coochey, CCNA, CCNAS
NetSecSpec Ltd
+44 (0) 7983 877438
http://www.coochey.net
http://www.netsecspec.co.uk
giles at coochey.net