Shell Programming and Scripting

hi everyone,
i need a script which would just print column into a text file

Code:

nmap 10.226.112.222
PORT STATE SERVICE 
7/tcp open echo 
13/tcp open daytime 
22/tcp open ssh 
23/tcp open telnet 
37/tcp open time 
1100/tcp open unknown

above nmap command gives us open ports on that IP. can i get a script which would just print PORT column into one text file or just SERVICE column into a text file.

Code:

nmap 10.226.112.222 | cut -d " " -f1 >file.txt

If you want service column to be printed you can use -f3 (3rd field)

Code:

c=1   # print first column
nmap | awk -v c=$c '{ print $c}'

thx guys for ur help

---------- Post updated at 11:14 PM ---------- Previous update was at 10:57 PM ----------

now i have a text file i.e file1.txt which shows open ports on particular system. i have another text file i.e file2.txt which shows a list of allowed ports on a system. for eg:
file2.txt
22/tcp ssh
23/tcp telnet.
can i have a script which would compare these text files ,file1 and file2 and close out all ports which r not allowed. i know only one way off turning off particular port or sevice i.e by commenting out particular service in etc/inetd.conf file on linux system.

You can produce the list of ports that should not be open like this:

Code:

nmap 10.226.112.222 | awk 'NR==FNR{P[$1]=$0;next}!P[$1]' file2.txt -

With you samples this will produce the following output:

Code:

PORT STATE SERVICE
7/tcp open echo
13/tcp open daytime
37/tcp open time
1100/tcp open unknown

If you want to then shut down those services I would do that manually or in controlled batch runs, but not automatically by a script.. Where exactly stop/start of services is controlled depends on your platform. Often there is some form of tooling like chkconfig to make this easier..
After you shut down the service you can then further tighten the system by adjusting firewall rules and/or tcp-wrappers, etc..

Code:

for i in `comm -23 1.txt 2.txt`
do 
  iptables -A INPUT --dport $i -j DROP
  iptables -A OUTPUT --dport $i -j DROP
done

hi rainboisterous, will u explain ur script a bit
here ,
for i in `comm -23 1.txt 2.txt`
here 1.txt contains all open ports on system by doing nmap
and 2.txt contains all allowed ports .
for e.g 1.txt might contain
7/tcp
13/tcp
22/tcp
23/tcp
37/tcp
and 2.txt contains
22/tcp
23/tcp
so ur script will commpare both text file and drop all ports apart from 23/tcp . please explain