On 02/28/2012 07:42 PM, Tom Eastep wrote:
> On 2/28/12 5:23 PM, jonetsu wrote:
>> Hmmm.. Not sure if the other one got to you, so here it is. Sorry for
>> any duplicate. Here is the dump. It was done in the following way: -
>> unit3: reboot w/o any iptable commands applied - start continuous
>> pings from unit1 - unit3: shorewall start - (continuous pingings
>> still going on) - unit3: shorewall dump 192.168.3.2 = unit1 = pinging
>> unit 172.30.159.103 = unit3 = shorewall unit 172.30.159.102 = unit2 =
>> pinging target unit eth1 <--> fe-4-2 unit3 fe-3-1 <--> fe-3-1 eth2 In
>> a parallel iptables-only test it is possible to immediately stop the
>> pingings when iptables rules are applied by flushing the whole thing
>> before applying any new rules. Thanks !
> 
> So everything else, other than the Shorewall version was the same in
> these two tests? Kernel, iptables, iproute2, ...?

I suspect that you were previously running on a different kernel version.

On the system that I am writing this on (Ubuntu 11.10, Kernel 3.0.0) ,
the /proc/sys/net/ipv4/netfilter/ip_conntrack_icmp_timeout setting has
value 30 (seconds). Experimentation has shown that the conntrack table
entry for ping stays around for 30 seconds after I stop pinging.

In contrast, on Centos-5 with kernel 2.6.18-274, the
ip_conntrack_icmp_timeout setting is the same but the conntrack table
entry is destroyed when the ping reply is returned.

So to stop an existing ping at with shorewall start/restart, you need to
flush the conntrack table ('shorewall restart -p'). That requires that
you install the conntrack utility program (usually, the package is
called simply 'conntrack').

-Tom
-- 
Tom Eastep        \ When I die, I want to go like my Grandfather who
Shoreline,         \ died peacefully in his sleep. Not screaming like
Washington, USA     \ all of the passengers in his car
http://shorewall.net \________________________________________________

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