Suprmicro BIOS Upgrade Using PXEBoot

SuperMicro provides DOS based BIOS upgrade utilities. These utilities are not bootable making it difficult to apply BIOS update remotely. Being a Linux guy I have different flavors of PXE bootable Linux images for Debian, Centos, RedHat, etc. Did not try to PXEboot DOS yet so here it is.


Windows7 VM on Xen

Xen HVM allows creating Windows VM. I have successfully created windows-xp and windows7 VM on Debian squeeze running xen 4.0. Windows kernel do not support Para virtualization that means your processor should have hvm capabilities to run windows VM.


Windows Update Via Squid Proxy

Windows update fails, if your squid proxy server running with default configuration. You will see similar lines in log. Notice the last line it says 0 bytes received If you copy paste that link in your browser the file successfully downloads. (more…)

How to install 3.2 bpo (backports) kernel on debian system?

Many of you must be using xen-amd64 kernels shipped with squeeze stable. The latest stable version 2.6.32-5-xen-amd64 has some problems in handling interrupts. DomU running on Dom0 kernel 2.6.32-5-xen-amd64 become unresponsive some time. The fix is to upgrade kernel to 3.2.0-0.bpo.2-amd64.

Zimbra Custom Transport Maps

When there is more than one MTA in an organisation, you need transport maps to tell each MTA where to route mails. We had Lotus Notes and Zimbra. There is an option in Lotus Notes to send mail of non-existing users to external SMTP server. In Zimbra we can you postfix transport maps to use different SMTP gateway for specific users.

BNX2 Link Disabled When High Traffic

Recently I had strange issue with one of my xen sever running on ProLiant ML370 G5 hardware. As I started rsync from other machine to this box which is in same LAN, the port goes in to disabled state. The server works fine in normal network load. The interface starts to flap after starting rsync.I changed cables, ports, tried different switch, swapped eth0 to eth1 but no joy. After googling I found solution to this problem is to increase Ring RX buffer.


Rollback RPM

Our monthly vulnerability mitigation policy wanted us to upgrade our vulnerable nss_ldap package to latest version. I went ahead and did the upgrade. After consulting CERT and various CVE and NVD site I found the upgrade was not needed as current version was not having any vulnerabilities. Sadly the new version installed had vulnerabilities according to CVE so it was time to revert back to earlier version. Here is how I did it.