#!/bin/bash
#27/02/2010 "Osfigment"
#linux os spoofing kludge using systcl 
#written by submitting student (in vi!) for Network security 4 CA resit
#concept and file format based on osfuscate[http://www.irongeek.com/i.php?page=security/osfuscate-change-your-windows-os-tcp-ip-fingerprint-to-confuse-p0f-networkminer-ettercap-nmap-and-other-os-detection-tools] by anonymous  
#use at own risk; potentially dangerous, badly written, and only nominally tested.

ospro="$1" #get profile
oldifs="$IFS" #store Interfield separator for later reset
IFS=' = ' #set IFS for  a space = space delimeter
if [ ! -e "$ospro" ]; then
	echo "pass an os profile to the script"
	exit
fi
while read parm val # cycle through profile entries
do 
	case $parm in
		ttl)
			kattl=$val ;;
		stamp)
			kastamp=$val ;;
		pmtu)
			kapmtu=$val ;;
		urg)
			kaurg=$val ;;
		window)
			kawindow=$val ;;
		sack)
			kasack=$val ;;
		mtu)
			kamtu=$val ;;  
esac
done < "$ospro"
echo "ttl =" $kattl
echo "stamp ="$kastamp
echo "pmtu =" $kapmtu
echo "arg =" $kaurg
echo "window =" $kawindow
echo "sack =" $kasack
echo "these are the values found; check and "yes" to continue,"
read amen
if [ ! $amen = yes ]; then
	echo wise
	IFS="$oldifs" # just in case it doesnt reset properly <.<
	exit 
else 
	echo "using sysctl and /proc/sys/net to screw up your system; startup system configuration is not affected"
	#default time to live
	sysctl net.ipv4.ip_default_ttl="$kattl"
	sysctl net.ipv4.tcp_timestamps="$kastamp"
	#MTU discovery value
	sysctl net.ipv4.ip_no_pmtu_disc="$kapmtu"
	#urgent traffic flag
	sysctl net.ipv4.tcp_stdurg="$kaurg"
	#Selective Acknowledgement (rfc2018)
	sysctl net.ipv4.tcp_sack="$kasack"
	#modifies default and max receive and transmit window size
	if [ "$kawindow" != 'x' ]; then 
		echo $kawindow > /proc/sys/net/core/rmem_max
		echo $kawindow > /proc/sys/net/core/wmem_max
		echo $kawindow > /proc/sys/net/core/rmem_default
		echo $kawindow > /proc/sys/net/core/wmem_default
	fi
	#MTU is imprudent to mess with, and does little good either way
fi
IFS="$oldifs"