[CentOS] strange network problem
michael.schumacher at pamas.de
Thu Mar 4 11:00:42 UTC 2010
I am trying to fix a problem I have for about a week now.
The environment is:
--several independent servers with Centos5.4 on the latest patchlevel
(example will be server2) All of them are working properly.
--a machine with Xen installed to host some virtual machines
--domu servers on xenserver1 (crmserver1, winserver1)
The whole network is connected with a Lancom router to a DSL line.
Some days ago I noticed that server2 was updated properly, but
xenserver1, crmserver1 and winserver were not updating the OS
properly. They seemed to be cut off the internet. I can ping from all
to all servers internally, I can ssh from all to all servers
internally and I can browse the Internet from server2 successfully
(using IP-numbers and hostnames), but xenserver1 and its domu clients
could not connect to the internet. I checked the firewalls on
xenserver, and crmserver1. They seemed to be OK and stopping them with
"etc/init.d/iptables stop" didn't solve the problem.
I can resolve hostnames:
>[root at xenserver1 ~]# nslookup www.centos.org
but I cannot browse neither to "elinks http://www.centos.org" nor to
18.104.22.168, however, I can ping www.centos.org successfully.
the network routes seem to be OK :
>[root at xenserver1 ~]# route
>Kernel IP routing table
>Destination Gateway Genmask Flags Metric Ref Use Iface
>10.1.1.0 * 255.255.255.0 U 0 0 0 eth1
>192.168.122.0 * 255.255.255.0 U 0 0 0 virbr0
>169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
>192.168.0.0 * 255.255.0.0 U 0 0 0 eth0
>default LANCOM_1751_1.p 0.0.0.0 UG 0 0 0 eth0
(eth1 is a drbd interface)
> [root at crmserver1 ~]# route
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use Iface
> 169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
> 192.168.0.0 * 255.255.0.0 U 0 0 0 eth0
> default LANCOM_1751_1.p 0.0.0.0 UG 0 0 0 eth0
Has anybody any clue where to look?
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