Linux/UNIX server access to your serial consoles anywhere and anytime

Posted on in Categories Howto, Linux, UNIX last updated May 31, 2006

This article explains howto provide worldwide access to your serial consoles relatively low-cost commodity components running your favorite Unix-variant (Linux) operating system along with an open source software package.

FTA “…Like many computing centers, we recently experienced some growth and needed a way to reduce our space/power/heat footprint in the datacenter. Our use of physical character console and keyboards attached directly to servers has given way to racks filled with high-density headless servers, KVM switches, network cables, and power strips…

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FreeNAS server howto

Posted on in Categories FreeBSD, Linux, News last updated May 31, 2006

Turn your old PC into NAS (Network attached storage) server with FreeNAS.

FTA “…FreeNAS, an open source NAS server, can convert a PC into a network-attached storage server. The software, which is based on FreeBSD, Samba, and PHP, includes an operating system that supports various software RAID models and a Web user interface. The server supports access from Windows machines, Apple Macs, FTP, SSH, and Network File System (NFS), and it takes up less than 16MB of disk space on a hard drive or removable media.

FreeNAS is free to use and deploy without cost. It’s an open source project published under the BSD license. The software is popular enough to have gotten more than 20,000 downloads last month…

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Poll: Are you going to try or upgrade current Linux distro to enterprise grade Ubuntu Linux?

Posted on in Categories Linux last updated May 30, 2006

Our very first, nixCraft poll we asked readers of this blog the question:

Do you own or recommend AMD64 based system?

Thanks to everyone, total 670 people responded to the poll. Results are as follows:

  • 89% said either they own or recommend AMD64 based system
  • 7% do not recommend it at all
  • 4% recommend Intel based system

I am planning to purchase new server based on dual AMD64 for my home/office network. It will run either Red Hat enterprise or Debian Linux. 🙂

New poll: Are you going to try or upgrade to enterprise grade Ubuntu Linux (code-named Dapper Drake)?

New Enterprise-Level Ubuntu Due This Week and our new poll question is:

Are you going to try or upgrade to enterprise grade Ubuntu Linux ?

Originally, Ubuntu Linux was introduced as an easy to use desktop Linux os. Now they are introducing enterprise version. Debian is stable and perfect choice for (besides RHEL/Suse and other Linux distros) my server requirements. Therefore, I am just wondering if you: Are you going to try or upgrade to enterprise grade Ubuntu Linux?

Iptables allow CIPE connection request

Posted on in Categories Iptables, Linux, Networking, Security, Troubleshooting last updated May 30, 2006

From my mail bag:

How do I accept CIPE connection requests coming from the outside?

CIPE stands for Crypto IP Encapsulation (see howto Establishing a CIPE Connection) . It is used to configure an IP tunneling device. For example, CIPE can be used to grant access from the outside world into a Virtual Private Network (VPN). All you need to find out CIPE number, once you got the number (device name) append following two IPTABLE rules (add rule to your iptables script) to script:

Iptables rules:

Add the following rules to your iptables script or configuration file:

iptables -A INPUT -p udp -i cipcb0 -j ACCEPT
iptables -A OUTPUT -p udp -o cipcb0 -j ACCEPT

CIPE use its own virtual device. It is use to transmit UDP packets so the above rule allows the cipcb0 interface to incoming request (no need to use eth0).

Replace cipcb0 with your actual device name.

References:

Running Google earth on Linux (upcoming Google port)

Posted on in Categories Linux, News last updated May 29, 2006

After picasa port to Linux, it looks like Google is planning to release Google earth for Linux operating systems.

According to Wine Weekly Newsletter, Google is porting Google earth to Linux. You can read the details here and here.

Google earth is really good application and once it is released I can kick the a$$ of Windows XP forever 😉

Found via Digg

Performance Tuning for Linux swap partition

Posted on in Categories Linux, Troubleshooting, Tuning last updated May 29, 2006

Tuning swap partition my result into a good system performance. You can tune swap by editing /etc/fstab file.

For example if you have two partitions as follows:
/dev/sdb3
/dev/sdc3

Now Linux system will only use one partition at a time. It will use next partition only if first partition exhausted. Each swap area has a priority, either high or low. The default priority is low. Within the low-priority areas, newer areas are even lower priority than older areas.

According to swap man page: All priorities set with swapflags are high-priority, higher than default. They may have any non-negative value chosen by the caller. Higher numbers mean higher priority. Swap pages are allocated from areas in priority order, highest priority first. For areas with different priorities, a higher-priority area is exhausted before using a lower-priority area. If two or more areas have the same priority, and it is the highest priority available, pages are allocated on a round-robin basis between them.

This may result into performance issue as a new process needs to be swapped to disk it may have to wait until another process is swapped out. So open your /etc/fstab:

# vi /etc/fstab

Find out line that read as follows:

/dev/sdb3 swap swap default 0 0
/dev/sdc3 swap swap default 0 0

Replace it as follows:

/dev/sdb3 swap swap pri=0 0 0
/dev/sdc3 swap swap pri=0 0 0

Restart the system or turn on and off swap to take effect with swapon command:

# sync;sync;swapoff -a
# swapon -a

The result of above tuning is that your system should able to use any one of the swap partition independently. Please note that this hack is only useful if your system uses swap.

Further readings:

Howto: Building a Self-Healing Network with NAGIOS and Cfengine

Posted on in Categories Linux, Networking last updated May 29, 2006

This is a very nice article/howto about building a self-Healing Network.

FTA “…Computer immunology is a hot topic in system administration. Wouldn’t it be great to have our servers solve their own problems? System administrators would be free to work proactively, rather than reactively, to improve the quality of the network.

This is a noble goal, but few solutions have made it out of the lab and into the real world. Most real-world environments automate service monitoring, then notify a human to repair any detected fault. Other sites invest a large amount of time creating and maintaining a custom patchwork of scripts for detecting and repairing frequently recurring faults. This article demonstrates how to build a self-healing network infrastructure using mature open source software components that are widely used by system administrators. These components are NAGIOS and Cfengine…

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Howto: FreeBSD, OpenBSD, and NetBSD package management

Posted on in Categories FreeBSD, OpenBSD, UNIX last updated May 27, 2006

This is a step by step guide for BSD operating systems, which discusses the basics of package management. Each member of the BSD family has a slightly different approach for package management, but all share common themes,

Article covers:
a) FreeBSD Ports and Packages
b) OpenBSD Ports and Packages
c) NetBSD pkgsrc

FTA “…Whichever BSD you use, the basics of package management are similar. Tools such as pkg_add and pkg_delete are available and, although they may differ slightly in usage, moving between them is relatively easy…”, Read more

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Interview: Red Hat's open source scholarship challenge

Posted on in Categories India, News, RedHat/Fedora Linux last updated May 27, 2006

IIT-B and Red Hat India is offering The Open Source challenge scholarship for students. Most of students in my university write projects using Java, Oracle or Microsoft development (C/C++ or .NET) tools.

There is no dearth of IT talent in India, but for a country that churns out thousands of IT students every year, the number of Indian contributors in the open source software (OSS) world is disproportionately low, due in part to a lack of proper mentoring. This is 100% true and to encourage more students to go into OSS development, the Kanwal Rekhi School of Information Technology (KReSIT) at the Indian Institute of Technology Bombay partners with Red Hat for an open source scholarship challenge each year

There an email interview with Venkatesh Hariharan, head of Open Source Affairs at Red Hat India and coordinator of the challenge, provides details about the event.

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Linux: Setup a transparent proxy with Squid in three easy steps

Posted on in Categories CentOS, Debian Linux, Howto, Linux, Networking, RedHat/Fedora Linux, Squid caching server, Ubuntu Linux last updated May 27, 2006

Y’day I got a chance to play with Squid and iptables. My job was simple : Setup Squid proxy as a transparent server.

Main benefit of setting transparent proxy is you do not have to setup up individual browsers to work with proxies.

My Setup:

i) System: HP dual Xeon CPU system with 8 GB RAM (good for squid).
ii) Eth0: IP:192.168.1.1
iii) Eth1: IP: 192.168.2.1 (192.168.2.0/24 network (around 150 windows XP systems))
iv) OS: Red Hat Enterprise Linux 4.0 (Following instruction should work with Debian and all other Linux distros)

Eth0 connected to internet and eth1 connected to local lan i.e. system act as router.
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