Tag Archives: Linux

Troubles installing CentOS on XenServer

You have a XenServer 6 or 7, and you have troubles installing CentOS (6 or 7) : the installer loads, but all you get is a black screen …

This is a known issue, and I’m wondering why it wasn’t fixed because it’s there for so long.
When having the boot menu, hit “tab” to show the option, and add the following :

modprobe.blacklist=bochs_drm rhgb

And then it worked !

https://bugs.xenserver.org/browse/XSO-353

https://discussions.citrix.com/topic/364226-centos-7-1503-installer-gives-blank-screen/

 

using a secured relay in Postfix

I have a server on a LAN that need to send emails. Of course, this server has access to the internet through NAT, but for emails it is a bit more difficult : nowadays, email servers are checking many things when receiving emails : reverse, ‘from’ field, etc. and you may not have access to this kind of tuning for the internet IP address used with your NAT. So I needed to configure a relayhost, with direct access to the internet, that would accept my incoming email and relay it through normal channels. But I don’t want this server to be an open relay, so I have to setup authentication between them.

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Using auditd to troubleshoot file reads

Today I will talk about auditd, a very powerfull tool to debug anything you need in a linux platform. In this very case, I had a problem with a mail server using all IO available. ‘iostat’ command told me it was reads ops that saturate it. A mail server has many process, so using “strace” is not helpful here. I choose to use auditd.

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