Re: I need a clever solution for two Bittorrent machines behind a firewall

[Jochen Radmacher <jradmacher@gmx.de>]

Hi,
Kenneth Porter wrote:

> --On Thursday, November 18, 2004 10:03 AM -0700 Brad Morgan 
> <B-Morgan@concentric.net> wrote:
>
>> I'm using a Linux firewall with IPTables as my home firewall.
>
>
> Take a look at "port triggering". This is a feature in the Linksys 
> WRT54G, which uses uClinux under the hood. When an outbound connection 
> is seen to a particular port, a port forwarding rule is installed for 
> the internal client. I'm guessing this is done by monitoring the 
> iptables logs and installing a custom chain on demand that's removed 
> after a period of inactivity.
>
I'm using a simple script to detect when someone connects to the 
battle.net . The basic Idea is to check for /proc/net/ip_conntrack for 
battle.net connections. Here is a simple version which has to be run 
every n minutes.
Greets
 Jochen Radmacher
---- cut here ----
#!/bin/bash
CONNECTED=0;
#Bugfix for netfilter bug 227
IPADDR=$(/sbin/ifconfig | grep -i "ppp0" -A 1|grep "inet addr"|cut -d " 
" -f 12|
cut -d ":" -f 2)

#you can repeat the following  4 lines with different argument for grep 
to make an 'OR'
egrep '213\.248\.106\.' /proc/net/ip_conntrack |grep $IPADDR >/dev/null
if [ "$?" -eq "0" ]; then
CONNECTED=1;
fi

if [ "$CONNECTED" -eq "1" ]; then
#do something
iptables -A ....
else
iptables -D ....
fi