Shell Programming and Scripting

Hi All,
I need an urgent assistance please .

My case below:
I have a list of 500 IP addresses.
All These ip addresses are mapped/connected to different machine kinds : NT, Linux, Switch, Router ,FW, and so on.

My Requirement is to filter from all this ip address only the Linux machines.
In other words,to create a mapping of all the Linux (Centos) Machines.

Now I do not sure what would be the best way to do it.

In order that operation will performed on a practical way,
i have an central linux server that can be consider as an SSH Server,Although he did not ,Since it still without an organized hosts list of all Linux servers in the organization, and of course it does not connect to all servers without a password.

But for the operation that will needs to perform, this server can communicates on the LAN with all the linux machine with Ping and SSH , with all this Linux servers that exist behind the ip addresses list .

i thought maybe build a bash script , that will runs from the central server, on all the IP Address , and during the action, it will sent the results into a text file , output from the 500 IP Address that it was able to open them session in SSH.
Is this the right way? Is there something else?

Please Assist.

You should check out the output of:

Code:

nmap -O -v $hosname

Do you guys not have a network diagram? We can tell by IP what switch something is connected to, and this tells us right away: desktop PC, unix box, windows server, etc.

I am assuming that the linux, NT, etc boxes have names like Server1 or whatever.
What you want to do requires some sort of human intervention.

Your first step would be to get the node names of things. Why? Because people tend to name things in such a way that you get meaning from the name. This will allow you to winnow the list down to something manageable.

Let's assume you have a file with 500 ip addresses in it. I'll call it ip.dat. This is a bash script example.

Code:

while read ip
do
  nslookup "$ip"
done < ip.dat > outputfile

The file called outputfile requires humans to read it. So get it into an editor.
You should be able to manually eliminate a lot of ip's from the list. From that point you will have to login via ssh to verify what each box is. If the name of the box does not tell you.