This article is bit different then the series of Linux Internal which I am posting since long time.  I was looking for some good source code browsing tools.   There are lot many cscope. kscope and tags. This post details about setting ctags and working with it for browsing code. Continue Reading »

One of the fundamental question, which TCP answer is the Protocol suited for higher transmit rate. So how fast a TCP can go? What all the performance and reliability issues with TCP as transfer rate goes up and up.
PAWS (Protection Against Wrapping Sequence) is one such consequence as the network bandwidth goes up. Continue Reading »

TSO Explained……

As I was going through some basic features supported by TCP, I came across the TSO feature which look very simple and has a very elgent design and implemnetation in Linux.

I would like to put some light on the some of the facts collected at looking books and code. Hope it will be useful to someone.  Continue Reading »

This Post is an update to my previous post, to find the IP address for xen VM. Previous post requires to specify network and subnet information. I have tried to calculate those information in the script itself.
Note: Network and Subnet  calculation has to done on Ubuntu 9.10 and Linux route tool. I am not sure if it works of anything else there than this. So use at your own risk. Continue Reading »

I have looked around the way to find the IP address for Xen guest without login to guest. There were couple of posts and Xen FAQ which list some methods.

The following code is very similar to Xen FAQ post in Network section.


But post says use tcpdump with guest mac address to find the Ip address. I am not sure how, because someone has to generate the traffic to the guest for tcpdump to capture packets e.g ping <guest ip>. But again it requires ip address of guest no?

I have changed it a bit using nmap tool. Hope all of you find it useful.


# Find the ip address for xen guest without login the machine.
# it needs nmap and some standard linux tools
# install nmap e.g apt-get install nmap
# set -x
printf “Enter guest ID: “
read ID

# Use xenstore to find the mac associated with VM
mac=`xenstore-read /local/domain/$ID/device/vif/0/mac`
umac=`echo $mac | tr “[:lower:]” “[:upper:]”`

# Search the local networking for all up machines and find the IP address.
ip=`nmap -sP $network/$subnet |  grep -B 2 $umac | grep Host | awk ‘{print $2}’`
echo “IP address for Guest ID $ID is \”$ip\””

# Copy the above code in Xen dom0 machine. Install nmap tools (e.g apt-get install nmap)

# Change the permission of script using chmod +x <script name>

# Execute ./script-name <network> <no of bits which represent network>   e.g. ./xen-guest-ip 24

# You need to be familiar with networking address type

# Next version for the script I will try to automate the network and subnet calculation.

Hope it will be useful to someone

Note: This could take some time to finish because scanning whole network could take noticeable time.


First Blog

Heard about blogging long back and i do follow lots of blogs using google reader. Now its time to move on and write my own blogs about my work experiences (technical) , new technologies and many more.  Any comment or Suggestion will be appreciated.


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