Ubuntu Idyll Cisco Study Environment

I have written a few posts in which I mentioned the amazing GNS3/Dynamips/Dynagen set of tools that enable you emulate a Cisco network …. also a great too used to prepare for the Cisco CCIE lab exam [Professor of Internetworking]

Here are a couple of things I have used that make creating and using labs a nirvana experience in Ubuntu … [constant flow for those who understand Emotional Intelligence]

  1. Because I hate having multiple console windows open, one for each router which is the default behaviour of GNS3, I wrote the script [tamonet.sh] in the previous post that essentially takes as an arguement your topology (.net) file and then opens each router console in a separate tab in gnome-terminal.
  2. I modified my gnome-terminal profile so that my background is translucent. That way, I can have a document (e.g a workbook) I refer to in the background and read instructions or make references without having to switch windows.
  3. Initially, to launch my lab with my tamonet.sh script, I would open up either a terminal or the RUN application box [Alt-F2] and issue the command …. that is until I discovered awn-terminal. Boy! …. first of all, AWN is a cool dock application for Ubuntu and one of its applets is a nifty cool terminal that you just click and it pops up a next-gen-like translucent terminal. You just type in your command and as soon as u move focus from it, it automatically closes … no clutter on your desktop!!
  4. And finally … when I am doing such work, I play music. Mozart is ideal for me but I generally prefer any kind of music without vocals. It is the vocals I find distracting. So for me, to complete the ensemble, it is Mozart, Beethoven, Tchaikovsky or soundtrack music [Prison Break, Stargate etc]

Given what I mostly do these days [putting in my 10000 hours to master my craft as a network engineer] and my passion for Ubuntu … I enjoy every single moment I spend building and executing scenarios and everyday, I say thank you to the guys who selflessly make all this possible …and it reminds me to keep sharing what little I know. Happy Valentines day guys and babes … do spend vals with someone real … far away from your laptop ok?

Open GNS3 Router Consoles in Multiple Tabs in a Single Window [GNOME]

As a follow up to my previous post of the above topic, I finally put together a script. I have two scripts, one specifically written for the Internetworkexpert Dynamips topology. The second one can will log into any topology – it takes the name of the .net file as an argument for example:

$./tamonet.sh BGPlab.net

Just copy this code, put them in a file with the .sh extension and  make then run them from a command line AFTER you have started your routers in GNS3.


# The purpose of this scrip is to launch all running Dynamips router consoles in such a way that all consoles exist
# as tabs in a single terminal windows, rather than the 
#default behavior to open multiple windows that just clutters the desktop.
#Script written by Mukom Akong TAMON [mukom to tamon at gmail dot com] .....
#Use and distribute freely .... just give me credit for creating it ok? ... ;-)
#Save this with an sh extension, make it executable and then you can run either from
#inside an existing terminal or you press ALT+F2 and then run it. You must pass it the name of the .net file of your current lab
#e.g ./tamonet.sh BGP-Lab01.net
#It is best if you copy the script so it is in the same directory as the directory in which the .net file is.
#Obviously, this script only works for Linux distributions that are using GNOME eg Ubuntu.

TELNETTABNAME1=/Users/mukom/tmp/telnettabname1	#Initial set of command arguments for gnome terminal
TELNETTABNAME2=/Users/mukom/tmp/telnettabname2	#Strip away the tab from the commands -- just in case
TELNETTABNAME=/Users/mukom/tmp/telnettabname		#the commands sorted so we have things sequentially

#First delete the files if they exit
rm -f  $PORTS
rm -f  $NAMES
rm -f $LASTCMD

#Xtract the ports from .net file and put them into ports file in /tmp 
grep -E console  $1 | sed s/console\ =\ // | tr -d [] | tr -s '[:blank:]' >> $PORTS

#Create corresponding file that containts the names
#grep -E ROUTER  $1 | sed s/ROUTER\ // | tr -d [] | tr -s '[:blank:]' >> $NAMES
grep -E '\[\[ROUTER'  $1 | sed s/ROUTER\ // | tr -d [] | tr -s '[:blank:]' >> $NAMES

#This block constructs the telnet commands for each router and writes them to $TELNETTABNAME
for i in $( cat $PORTS ); do
#	let inst=inst+1
	#echo >> $TELNETCMDS "telnet localhost $i -t" 
#	echo >> $TELNETCMDS "\"telnet localhost $i\" -t" 
	echo >> $TELNETCMDS "\"telnet localhost" "$i\"" ' -t' 

#Combine the telnet command with the device name on same line

#replace all tabs with a single space.
#cat $TELNETTABNAME #| tr '\t' '" -t "' 

#Now sort the file

#how many lines [routers] in the file?
routers=`wc -l $TELNETTABNAME`	#count lines in the file and set result as variable routers.
routers=${routers%$TELNETTABNAME}  #Make the routers variable an integer?
echo "There are $routers Routers in this topology"
let "routers = $routers+1"
#declare -i routers    #This seems not to serve any useful purpose that I know of
# echo "I now start with a router count of $routers"

#This block reads in the commands from a file and assign each line to a dimensioned variable R[x]
	while [ "$counter" -lt "$routers" ]
		read R[$counter]
		let "counter=$counter+1"

#This block just prints out the contents of the dimension - I want to be sure I read the right things into the variables
while [ "$counter" -lt "$routers" ]
	echo ${R[$counter]}
	let "counter=$counter+1"

#Build the gnome-terminal command and options from the contents of the R[x] dimension
let "routers=$routers-2"  #One main window and then the -2 so we cover just the right number of tabbed auxilliary windows
command="gnome-terminal --window --maximize -e ${R[$counter]}"
while [ "$counter" -lt "$routers" ]
		let "counter=$counter+1"
		command="$command --tab -e ${R[$counter]}"
		#echo $command
echo >>$LASTCMD $command
chmod 777 $LASTCMD
#I can delete these files now, since I no longer need them --- just house cleaning
rm -f  $PORTS
rm -f  $NAMES

I appreciate any modifications …. and this works for me … so I don’t have to get KDEbase libararies just for konsole4KDE. I hope u enjoy it.

Simulating a Host in Dynamips/GNS3

For those who don’t know what Dynamips is …. aaaaaaaahhh … it is a very cool piece of software that allows us to emulate any Cisco router and even the PIX. It is a very useful tool for experimenting with Cisco-based networks and one of the cheapest ways to prepare for the CCIE lab. I use it for the later purpose and also to get some hands-on practice with various networking technologies. GNS3 is a very cute graphical front-end to Dynamips which is more suited for adhoc experimentation due to the simply way you can create any topology by dropping devices and connecting them. I was watching a video class on IPv6 when something the instructor said hit me “… without the ipv6 unicast-routing command, this router will not function as a router”! …. immediately I fired up my copy of GNS3 and to simulate a host, I added a router and proceded thus to make it a ‘host’ 1. Disabled routing [no ip routing in global config mode] 2. Configured and IP address and subnet mask on an interface and enabled the interface. 3. Gave the router a default gateway by typing ip default network a.b.c.d where a.b.c.d is the IP address of the router to which this ‘host’ is connected. An viola! I had a host I could ping from. This enables me to simulate a LAN connected to the router … definitely a more elegant way that using loopback addresses which is what I was using until now. So experiment away and drop me any suggestions.