On Wed, Oct 28, 2009 at 16:36, Marcus Moeller mail@marcus-moeller.de wrote:
You would have to specify the required match space across multiple rules, maybe something like this:
iptables -A OUTPUT -p UDP -d $IP1-j DROP iptables -A OUTPUT -p TCP -d $IP1 -j DROP iptables -A OUTPUT -p UDP -d $IP2 -j DROP iptables -A OUTPUT -p TCP -d $IP2 -j DROP
That's what I am doing atm. Thanks for the update.
BTW, if you have some complex chain of action logic (more than just a simple -j DROP), you could simplify your rules by creating a custom chain and having the rules on the builtin chain (OUTPUT, or whatever) jump to your custom chain instead of DROP.
For example, If I wanted to use the same four rules from above, but I wanted to both log AND drop the incoming packets, a "naive" implementation might be something like this:
iptables -A OUTPUT -p UDP -d $IP1 -j LOG --log-prefix 'MYDROP: ' --log-level notice iptables -A OUTPUT -p UDP -d $IP1 -j DROP iptables -A OUTPUT -p TCP -d $IP1 -j LOG --log-prefix 'MYDROP: ' --log-level notice iptables -A OUTPUT -p TCP -d $IP1 -j DROP iptables -A OUTPUT -p UDP -d $IP2 -j LOG --log-prefix 'MYDROP: ' --log-level notice iptables -A OUTPUT -p UDP -d $IP2 -j DROP iptables -A OUTPUT -p TCP -d $IP2 -j LOG --log-prefix 'MYDROP: ' --log-level notice iptables -A OUTPUT -p TCP -d $IP2 -j DROP
You could do the same thing in a much more compact fashion by creating a custom chain called MYDROP:
iptables -N MYDROP iptables -A MYDROP -j LOG --log-prefix 'MYDROP: ' --log-level notice iptables -A MYDROP -j DROP iptables -A OUTPUT -p UDP -d $IP1 -j MYDROP iptables -A OUTPUT -p TCP -d $IP1 -j MYDROP iptables -A OUTPUT -p UDP -d $IP2 -j MYDROP iptables -A OUTPUT -p TCP -d $IP2 -j MYDROP
In programming, it would be analogous to factoring duplicative code into a common function. In this example, you really don't compress the expression very much (7 lines versus 8 lines). If you imagine a situation where MYDROP would contain 10 or 15 different actions, you'll understand how powerful it can be.
-Ryan