CentOS - Mar 2007 - The most weird thing i've ever seen (networking)

Hi,

I've installed a mail server using CentOS 4.4

Now, if i reboot the server remotely by ssh, when it cames up, i have no 
network.
The interface is up and everything looks pretty fine.
But i can't even ping other machines in the same intranet.

If i reboot it locally at the console, the network cames just fine.

Never seen nothing like this.

The mind boggles :(

Any ideas ?

Warm Regards,
M?rio Gamito

> -----Original Message-----
> From: centos-bounces at centos.org 
> [mailto:centos-bounces at centos.org] On Behalf Of M?rio Gamito
> Sent: Saturday, March 03, 2007 4:33 PM
> To: CentOS mailing list
> Subject: [CentOS] The most weird thing i've ever seen (networking)
> 
> Hi,
> 
> I've installed a mail server using CentOS 4.4
> 
> Now, if i reboot the server remotely by ssh, when it cames 
> up, i have no network.
> The interface is up and everything looks pretty fine.
> But i can't even ping other machines in the same intranet.
> 
> If i reboot it locally at the console, the network cames just fine.
> 
> Never seen nothing like this.
> 
> The mind boggles :(
> 
> Any ideas ?
> 
> Warm Regards,
> M?rio Gamito
>

Any log entries?

> -----Original Message-----
> From: centos-bounces at centos.org 
> [mailto:centos-bounces at centos.org] On Behalf Of M?rio Gamito
> Sent: Saturday, March 03, 2007 5:33 PM
> To: CentOS mailing list
> Subject: [CentOS] The most weird thing i've ever seen (networking)
> 
> Hi,
> 
> I've installed a mail server using CentOS 4.4
> 
> Now, if i reboot the server remotely by ssh, when it cames 
> up, i have no 
> network.
> The interface is up and everything looks pretty fine.
> But i can't even ping other machines in the same intranet.
> 
> If i reboot it locally at the console, the network cames just fine.
> 
> Never seen nothing like this.
> 
> The mind boggles :(
> 
> Any ideas ?
How do you attempt to ping the other machines after you reboot via ssh, at the
console?

Is it possible that a piece of network equipment is proxying the arp when you
reboot via the network and will not let go once the machine comes back up, but
when you reboot locally there is no network connection that would need arp
proxying so a proxy entry isn't created?

You would have had to turn on arp proxying somewhere for this to happen though
it doesn't happen automatically.

Need to know your network topology a bit more to fully diagnose this.

-Ross

______________________________________________________________________
This e-mail, and any attachments thereto, is intended only for use by
the addressee(s) named herein and may contain legally privileged
and/or confidential information. If you are not the intended recipient
of this e-mail, you are hereby notified that any dissemination,
distribution or copying of this e-mail, and any attachments thereto,
is strictly prohibited. If you have received this e-mail in error,
please immediately notify the sender and permanently delete the
original and any copy or printout thereof.

If you use DHCP and are connected to a cisco switch, sometimes the link 
won't come up (if you are using the default settings).

This may not be your specific problem but in general I recommend that 
you don't use DHCP on servers for this reason.

John.

M?rio Gamito wrote:
> Hi,
> 
> I've installed a mail server using CentOS 4.4
> 
> Now, if i reboot the server remotely by ssh, when it cames up, i have no 
> network.
> The interface is up and everything looks pretty fine.
> But i can't even ping other machines in the same intranet.
> 
> If i reboot it locally at the console, the network cames just fine.
> 
> Never seen nothing like this.
> 
> The mind boggles :(
> 
> Any ideas ?
> 
> Warm Regards,
> M?rio Gamito
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
> 
> 
> 

-- 
John Newbigin
Computer Systems Officer
Faculty of Information and Communication Technologies
Swinburne University of Technology
Melbourne, Australia
http://www.ict.swin.edu.au/staff/jnewbigin