executing a script!!

vishamr2000 · 07-26-2005, 06:50 AM

Hi to all,

I would like to know how to execute a script that contains an if-else
statement on a per-packet basis. The if and else part each contain
iptables rules that need to be executed ona packet basis? How can I do
that?I am using RH 9.

Any input will be most appreciated..

Warm regards,
Visham

Half_Elf · 07-26-2005, 11:54 AM

You can't really do this with iptables. Iptables rules are executed in the idea of "first found first applied" you just can't use if/then/else in there.
You better write some C/C++ application with sockets or maybe a perl script to do this. I doubt there is an easy "bash script" solution.

demian · 07-26-2005, 02:10 PM

You are a little vague on the details but this sounds like a job for the QUEUE target. This puts packets in the userspace where they can be handled with libipq. See man 3 libipq and http://www.netfilter.org/documentati...ter-faq-4.html

vishamr2000 · 07-27-2005, 04:40 AM

Hi to all,

Half_Elf and demian, many thx for the replies..

Is it possible to get a signal (i don't know from where, maybe a function or the NIC) just before every packet is sent out the NIC. The signal then cause the script to execute. MAybe that will cause the script to execute on a per-packet basis. But I don't know how to go about it. I thought about the QUEUE target but i'm not sure. What according to you should the things I should be looking at?

Thx in advance..

Warm regards,
Visham

Matir · 07-28-2005, 04:13 PM

Out of curiousity, WHY do you want to do this? Perhaps, rather than being hung up on this script, there is a better way to handle your situation. (And less complex, at that.)

vishamr2000 · 07-29-2005, 02:34 AM

Hi to all,

I am using ebtables and I need to implement load balancing on a per-packet basis. That's why i need to run the script after I know the packets have been declared valid and accepted (outgoing packets only).

The script contains an if-else statement containing rules, which cannot run in script more than once.

Regards,
Visham