bash – Page 4 – Ryan Schulze

How to install the latest Nmap for Debian/Ubuntu

August 21, 2013August 27, 2013Ryanbash, nmap, security

A quick & dirty script to download the latest version of nmap (sourcecode) and generate a deb and install it (so that it’s correctly in the package management). Yes, I know this is not much more than a glorified configure && make && checkinstall

#!/bin/bash

# some packages we will need. I put nmap in here to satisfy any dependencies like LUA
apt-get -qqy install checkinstall nmap build-essential

# get latest version
URL='http://nmap.org/dist/'
FILE="$(wget -qO - ${URL}|cut -d\" -f8|grep "tar.bz2"|sort -rn|head -n1)"

INSTALLED="$(dpkg -p nmap|grep Version:|awk '{print $2}')"

echo "Installed version: ${INSTALLED}, Downloaded version: ${FILE/.tar.bz2/}"
read -p "Compile and install new version? [Y/n] " answer
if [[ ${answer,,} = "n" ]] ; then
  exit 0
fi

echo "Downloading ${FILE}"
[[ -e  ${FILE} ]] || wget -qO ${FILE} ${URL}${FILE}
tar -xjf ${FILE}

cd ${FILE/.tar.bz2/}
./configure
if [[ ${FILE} =~ ^nmap-6.40. ]] ; then 
  # fixing an error in the 6.40 ncat Makefile
  sed -i 's/^LUA_LIBS.*/LUA_LIBS = $(top_srcdir)\/..\/liblua\/liblua.a -ldl -lm/1' ncat/Makefile
fi
make &amp;&amp; \
checkinstall -y

echo -e "\n Installed nmap version:"
$(which nmap) --version

#!/bin/bash

# some packages we will need. I put nmap in here to satisfy any dependencies like LUA

apt-get -qqy install checkinstall nmap build-essential

# get latest version

URL='http://nmap.org/dist/'

FILE="$(wget -qO - ${URL}|cut -d\" -f8|grep "tar.bz2"|sort -rn|head -n1)"

INSTALLED="$(dpkg -p nmap|grep Version:|awk '{print $2}')"

echo "Installed version: ${INSTALLED}, Downloaded version: ${FILE/.tar.bz2/}"

read -p "Compile and install new version? [Y/n] " answer

if [[ ${answer,,} = "n" ]] ; then

exit 0

echo "Downloading ${FILE}"

[[ -e ${FILE} ]] || wget -qO ${FILE} ${URL}${FILE}

tar -xjf ${FILE}

cd ${FILE/.tar.bz2/}

./configure

if [[ ${FILE} =~ ^nmap-6.40. ]] ; then

# fixing an error in the 6.40 ncat Makefile

sed -i 's/^LUA_LIBS.*/LUA_LIBS = $(top_srcdir)\/..\/liblua\/liblua.a -ldl -lm/1' ncat/Makefile

make && \

checkinstall -y

echo -e "\n Installed nmap version:"

$(which nmap) --version

Bash snippet, verify ctrl+c

July 10, 2013August 27, 2013Ryanbash, ctrl+c, trap

Lately I’ve been working on a pair of more elaborate scripts using ncat and openssl to transfer data between hosts. I’ll get around to posting it eventually, but until then a few small snippets that people may find useful.

Today we will catch ctrl+c and ask the user if he really want’s to terminate the script.

#!/bin/bash

initialize() { #{{{
  # Treat unset variables as an error
  set -o nounset
  trap verify_quit INT # verify ending script
  trap cleanup TERM EXIT # clean up if script exits
} #}}} 

verify_quit() { #{{{
  local timeout=10
  echo "Press ctrl+c again within ${timeout} seconds to end script"
  sleep ${timeout}
  [[ $? -gt 0 ]] &amp;&amp; cleanup
} #}}}

cleanup() { #{{{
  exit 0
} #}}} 

initialize
while [ true ]
do 
  # do stuff
  sleep 10
done

#!/bin/bash

initialize() { #{{{

# Treat unset variables as an error

set -o nounset

trap verify_quit INT # verify ending script

trap cleanup TERM EXIT # clean up if script exits

} #}}}

verify_quit() { #{{{

local timeout=10

echo "Press ctrl+c again within ${timeout} seconds to end script"

sleep ${timeout}

[[ $? -gt 0 ]] && cleanup

} #}}}

cleanup() { #{{{

exit 0

} #}}}

initialize

while [ true ]

# do stuff

sleep 10

done

The initialize() and cleanup() are my usual function names I have in every script, making sure general settings and variables are defined and that on exit any tempfiles get deleted.
What has been added was a trap for the INT signal (ctrl+c) which calls the verify_quit() function, giving the user 10 seconds to press ctrl+c again to exit (via cleanup()) or return back to wherever we were in the code. There is one unavoidable caveat, the first ctrl+c will kill whatever the script was doing before it jumps into the verify_quit() function.

Simple “try” function for bash

May 13, 2013August 27, 2013Ryanbash

Made a nice little try() function today for simplifying checking/dealing with return codes from commands. It uses the function text() I posted earlier to colorfy output: How to easily add colored text output in bash scripts. The function accepts 2 parameters, how it should behave if a problem occurs and the command to be executed: try <silent|warn|fatal> command

silent: save the return status in the global variable command_status
warn: if the command has a return code > 0, print a warning and save the return status in the global variable command_status
fatal: if the command has a return code > 0, print an error and exit

Obviously not as versatile as a python try/except, bu streamlines verifying the command return codes.
Example Usage:

try warn   false
try fatal  ls -al doesnotexist

1 2	try warn false try fatal ls -al doesnotexist

Output
Warning: ‘false‘ failed with return code –1–
ls: cannot access doesnotexist: No such file or directory
Error: ‘ls -al doesnotexist‘ failed with return code –2–

File: error_handling.sh

command_status=
function try() { #{{{
	if [ "$#" = "0" ]
	then # not enough parameters were provided
		echo "ERROR: sytnax is 'try &lt;silent|warn|fatal&gt; command'"
		exit 1
	fi
	local returncode=0
	local severity=${1}
	shift
	local cmd="${@}"

	$cmd
	returncode=$?

	if [[ ${returncode} -gt 0 ]]
	then
		case ${severity} in
			silent  ) 
				command_status=${returncode}
				;;
			warn  ) 
				printf "%s: '%s' failed with return code -%s-\n" $(text yellow "Warning") "$(text blue "${cmd}")" $(text yellow "${returncode}") 
				command_status=${returncode}
				;;
			fatal ) 
				printf "%s: '%s' failed with return code -%s-\n" $(text red "Error") "$(text blue "${cmd}")" $(text yellow "${returncode}")
				exit ${returncode} 
				;;
			* )
				printf "%s: Wrong usage of the try() function\n" $(text red "Error")
				exit 1
				;;
		esac
	fi
} #}}}

command_status=

function try() { #{{{

if [ "$#" = "0" ]

then # not enough parameters were provided

echo "ERROR: sytnax is 'try <silent|warn|fatal> command'"

exit 1

local returncode=0

local severity=${1}

shift

local cmd="${@}"

$cmd

returncode=$?

if [[ ${returncode} -gt 0 ]]

then

case ${severity} in

silent )

command_status=${returncode}

;;

warn )

printf "%s: '%s' failed with return code -%s-\n" $(text yellow "Warning") "$(text blue "${cmd}")" $(text yellow "${returncode}")

command_status=${returncode}

;;

fatal )

printf "%s: '%s' failed with return code -%s-\n" $(text red "Error") "$(text blue "${cmd}")" $(text yellow "${returncode}")

exit ${returncode}

;;

* )

printf "%s: Wrong usage of the try() function\n" $(text red "Error")

exit 1

;;

esac

} #}}}

Script to start minion in tmux

February 15, 2013Ryanbash, minion, scripting, security, tmux

Minion is a security project from Mozilla (link). It provides a user-friendly web interface to various security scanner tools. There is a webcast demonstrating the software (link).

The software requires a few services to run, and since I like having one script take care of starting everything with the right parameters, I threw together a simple shell script that sets up a tmux session with the services started in windows with the names of the services.

#!/bin/bash

session="minion"
http="0.0.0.0:8000"

cd /opt/minion

#-------------------------------------------------------------------------------

if [[ "$(tmux list-sessions|cut -d: -f1|grep "^${session}$")" == "${session}" ]]
then
  tmux -2 attach-session -t "${session}"
  exit
fi
tmux new-session -s ${session} -d

window="${session}:1"
tmux send-keys -t "${window}" 'top' Enter

window="${session}:2"
tmux new-window -t "${window}" -n "task-engine"
tmux send-keys -t "${window}" 'source env/bin/activate' Enter
tmux send-keys -t "${window}" 'minion-task-engine --debug' Enter

window="${session}:3"
tmux new-window -t "${window}" -n "plugin-service"
tmux send-keys -t "${window}" 'source env/bin/activate' Enter
tmux send-keys -t "${window}" 'minion-plugin-service --debug' Enter

window="${session}:4"
tmux new-window -t "${window}" -n "frontend"
tmux send-keys -t "${window}" 'source env/bin/activate' Enter
tmux send-keys -t "${window}" 'cd frontend' Enter
tmux send-keys -t "${window}" 'python manage.py syncdb' Enter
tmux send-keys -t "${window}" "python manage.py runserver ${http}" Enter

tmux -2 attach-session -t "${session}"

#!/bin/bash

session="minion"

http="0.0.0.0:8000"

cd /opt/minion

#-------------------------------------------------------------------------------

if [[ "$(tmux list-sessions|cut -d: -f1|grep "^${session}$")" == "${session}" ]]

then

tmux -2 attach-session -t "${session}"

exit

tmux new-session -s ${session} -d

window="${session}:1"

tmux send-keys -t "${window}" 'top' Enter

window="${session}:2"

tmux new-window -t "${window}" -n "task-engine"

tmux send-keys -t "${window}" 'source env/bin/activate' Enter

tmux send-keys -t "${window}" 'minion-task-engine --debug' Enter

window="${session}:3"

tmux new-window -t "${window}" -n "plugin-service"

tmux send-keys -t "${window}" 'source env/bin/activate' Enter

tmux send-keys -t "${window}" 'minion-plugin-service --debug' Enter

window="${session}:4"

tmux new-window -t "${window}" -n "frontend"

tmux send-keys -t "${window}" 'source env/bin/activate' Enter

tmux send-keys -t "${window}" 'cd frontend' Enter

tmux send-keys -t "${window}" 'python manage.py syncdb' Enter

tmux send-keys -t "${window}" "python manage.py runserver ${http}" Enter

tmux -2 attach-session -t "${session}"

How to break down CIDR subnets in Bash

December 11, 2012September 27, 2014Ryanbash, cidr, ip, math, subnet

I was playing around with subnets in bash recently and needed an elegant/easy way to split up a subnet into smaller subnets. First I used 2 functions I found on stackoverflow.com to convert an IP addresse to and from an integer. After that it was just a bit of math in bash to split up any networks too big.
Any network larger than $maxSubnet gets split up.
Here the useful code:

#!/bin/bash
. functions_ip2long.sh

input='10.1.4.0/22 10.2.2.0/24 10.3.3.128/25'
output=
maxSubnet=24

for pair in ${input}
do
  # split up the network and netmask
  network=${pair%/*}
  netmask=${pair#*/}
  if [[ ${netmask} -ge ${maxSubnet} ]]
  then # network is smaller than max. size. add it to the array
    output="${output} ${network}/${netmask}"
  else # network is too big. split it up into smaller chunks and add them to the array
    for i in $(seq 0 $(( $(( 2 ** (${maxSubnet} - ${netmask}) )) - 1 )) )
    do # convert network to long integer, add n * ${maxSubnet} and then convert back to string
      output="${output} $( INET_NTOA $(( $( INET_ATON ${network} ) + $(( 2 ** ( 32 - ${maxSubnet} ) * ${i} )) )) )/${maxSubnet}"
    done
  fi
done

echo ${output}|tr ' ' '\n'

#!/bin/bash

. functions_ip2long.sh

input='10.1.4.0/22 10.2.2.0/24 10.3.3.128/25'

output=

maxSubnet=24

for pair in ${input}

# split up the network and netmask

network=${pair%/*}

netmask=${pair#*/}

if [[ ${netmask} -ge ${maxSubnet} ]]

then # network is smaller than max. size. add it to the array

output="${output} ${network}/${netmask}"

else # network is too big. split it up into smaller chunks and add them to the array

for i in $(seq 0 $(( $(( 2 ** (${maxSubnet} - ${netmask}) )) - 1 )) )

do # convert network to long integer, add n * ${maxSubnet} and then convert back to string

output="${output} $( INET_NTOA $(( $( INET_ATON ${network} ) + $(( 2 ** ( 32 - ${maxSubnet} ) * ${i} )) )) )/${maxSubnet}"

done

echo ${output}|tr ' ' '\n'

Output of script:

10.1.4.0/24
10.1.5.0/24
10.1.6.0/24
10.1.7.0/24
10.2.2.0/24
10.3.3.128/25

10.1.4.0/24

10.1.5.0/24

10.1.6.0/24

10.1.7.0/24

10.2.2.0/24

10.3.3.128/25