Re: ip_conntrack

[Cesare Fontana <c.fontana@ieee.org>]

Bjoern Schmidt wrote:
> It is possible to clear all ore one entries in /proc/net/ip_conntrack
> without a reboot? I know there is a timeout, but i would like to remove
> them immediately if needed.

there is  an hack....

from:
http://lists.netfilter.org/pipermail/netfilter/2003-June/045080.html


send a fake ip packet (with RST set) to
firewall , to let it think the connection terminate .
	By this methode , I have the following script written , it work
well for me.
	To use this script , you must have hping2 installed , it can be
download from http://www.hping.org
--------- clr_conns start  ------------------
echo
echo "############################"
echo "# Edit by Youngh 2003.06.24 v1.1 "
echo "# Usage : clr_conns IpAddress"
echo "#    	This will clear all connections from this IP_Address"
echo "# Example:/root/clr_conns  10.0.3.3 "
echo "############################"
echo



if [ -z $1 ] ; then
	exit
fi


grep -E "^tcp .{10,25}ESTABLISHED src=$1 " /proc/net/ip_conntrack | while read 
line ; do
	S_IP=`echo $line | awk '{print substr($5,5)}'`
	S_SOCK=`echo $line | awk '{print substr($7,7)}'`
	D_IP=`echo $line | awk '{print substr($6,5)}'`
	D_SOCK=`echo $line | awk '{print substr($8,7)}'`	
	echo "$S_IP:$S_SOCK $D_IP:$D_SOCK"

	hping2 $D_IP -R -s $S_SOCK -p $D_SOCK -a $S_IP -k -c 1 >/dev/null 2>/dev/null &

done