After cloning a VMWare image I had noticed that my CentOS Linux server renamed eth0 as eth1, eth1 as eth2 and so on. This is due to wrong or duplicate mac address. To fix this problem login to your CentOS Linux server using console and type the following commands:
Looks nice but this hack is not for the faint hearted!
Old Gateway PC transformed into a Linux server with embedded display, which is a hacked portable B&W TV driven directly by the VGA card.
From my mailbag:
I turn off the PC at home or the office once in a while. Now, I’ve server at colocation center. Do we need to run server 24/7? I do reboot the server once a month. Is it advisable to completely power off a server once in a while instead of 24/7 running?
UNIX or Linux distros offers many flavors. Managing many UNIX like operating systems can be difficult. Here are few tips about selecting one perfect operating system for your business and sticking it with to save both money and time.
If you are running Linux, you have several alternatives to put second Ethernet interface for good use.
Slackware 12.1 has been released with kernel 2.6.24-5 and available for download.
Good news for all Debian / Ubuntu Linux fans. Sun has started to offer Ubuntu Linux based servers. Sun has systems competitively priced for small and medium businesses. Ubuntu is based upon rock solid Debian core. Look like Red hat and Novell going to have some nice competition. Sun offers x64-based systems certified for Ubuntu Linux:
* x64 Rack Servers
* Blade Servers
* x64 Workstations
* Workgroup Disk Storage
* Tape Automation
I’ve 5 Debian Linux servers with HP SAN box. Should I boot from SAN?
No, use centralized network storage for shared data or high availability configuration only. Technically you can boot and configure system. However I don’t recommend booting from SAN or any other central server until and unless you need diskless nodes:
[a] Use local storage – Always use local storage for /boot and / (root) filesystem
[b] Keep it simply – Booting from SAN volumes is complicated procedure. Most operating systems are not designed for this kind of configuration. You need to modify scripts and booting procedure.
[c] SAN booting support – Your SAN vendor must support platform booting a Linux server. You need to configure HBA and SAN according to vendor specification. You must totally depend upon SAN vendor for drivers and firmware (HBA Bios) to get thing work properly. General principle – don’t put all your eggs in one basket err one vendor 😉
[d] Other factors – Proper fiber channel topology must be used. Make sure Multipathing and redundant SAN links are used. The boot disk LUN is dedicated to a single host. etc
As you can see, complications started to increases, hence I don’t recommend booting from SAN.
This is a reader contributed article.
These days almost all server / laptop / desktop system has a gigabit Ethernet card (NIC) pre installed. Most servers are directly connected to internet using 100Mbps connections. You can save real power on your Linux server or desktop by operating at 100Mbps Ethernet speed. For example 1 gigabit link is going to consume more power than the power used at 100Mbps speed. Also note that not all systems actually use gigabit speed. For example my desktop system only used for browsing or chatting purpose or Linux web server used to display just static web pages. Now just calculate power consumption for 100 servers or 1000 desktop systems. Bottom line use Gigabit Ethernet speeds only when needed. Did you know – you can save 2 watts or more per Linux/UNIX/Windows server/desktop by just setting a correct speed 🙂
See current Ethernet card speed
Use ethtool comment to display current speed:
ethtool eth0 | grep -i speed
Set new speed and save power
Following command will set card speed to 100Mbps:
ethtool -s eth0 autoneg off speed 100
=> For more information see ethtool command and network interface speed, duplex . auto negotiate settings on Linux
About the author: Rocky Jr., is an engineer with VSNL – a leading ISP / global telecom company in India and a good friend of nixCraft.
This is a good analysis and sort of demonstration for all new Linux admin. It does shows how to do forensic kind of analysis on a cracked box. A good read for everyone ~ if you want to know how Linux server is cracked and turned into a zombie 😉