RE: iptables newbie

["Mark E. Donaldson" <markee@bandwidthco.com>]

The command defaults to the filter table if no table is specified  as an
argument.  Try  iptables -v -n -x -L -t mangle and see what you get.

-----Original Message-----
From: netfilter-admin@lists.netfilter.org
[mailto:netfilter-admin@lists.netfilter.org] On Behalf Of Johan Cimen
Sent: Saturday, December 27, 2003 9:05 AM
To: John A. Sullivan III
Cc: netfilter@lists.netfilter.org
Subject: Re: iptables newbie


A more precise explanation of my problem:
When I use below command within my script,

iptables -t mangle -A OUTPUT -o $IFACE -p UDP --dport 7001 -j TOS --set-tos
0x10

where I have an iptables -L at the very end, I can see the results:

Chain OUTPUT (policy ACCEPT)
target  prot opt source  destination
TOS     udp -- anywhere  anywhere    udp dpt:7001 TOS set
Maximize-Throughput

But very next used: iptables -L at my prompt shows nothing else than
headlines. The results shown from my script are disapeared! iptables -L was
the last thing my script did before exit 0.

> On Sat, 2003-12-27 at 08:31, Johan Cimen wrote:
> > Problem that I have is:
> > 1. I cannot use:
> >    iptables -t mangle -A OUTPUT -o $IFACE -p UDP --dport 7001 -j TOS 
> > --set-tos 0x10
> >    Using iptables -L shows nothing under OUTPUT headline.

#2 below was just an example used at prompt. If I use iptables command
without tables, because tables used at prompt are not shown:
iptables -A OUTPUT -o $IFACE -p UDP --dport 7001, And after that using
iptables -L shows:

Chain OUTPUT (policy ACCEPT)
target  prot opt source  destination
        udp -- anywhere  anywhere

But if I use PREROUTING or POSTROUTING it says: No chain/target/match by
that name. I cannot use PREROUTING and POSTROUTING at prompt, which is
possible in script.

> > 2. I cannot use (just an example, nothing to do with what i want to do):
> >    iptables -A POSTROUTING -o $IFACE -p UDP --dport 7001

> >    iptables says: No chain/target/match by that name
> >    Above iptable command works for INPUT, FORWARD and OUTPUT chains.


> On Sat, 27 Dec 2003, John A. Sullivan III wrote:
> Are you remembering to specify the table with -t mangle or -t nat if 
> you are not using the filter table? You do this in rule #1 but not 
> rule #2 and if you do iptables -L OUTPUT you will see the rules of the 
> filter table OUTPUT chain and not mangle or nat.  Good luck - John

Yes I understand that I have to use -t mangle if I dont use filter table.
But I cannot se the results from my commands included with -t mangle. Is
this not possible? If not, why is my script showing results that are
disapeared after execution of my script terminations?

What I am trying to explain is that I got results when I am using iptables
commands in my script and those are disapeared after the termination of my
scripts. And I am trying to say that if I use iptables commands without
tables and without PREROUTING, POSTROUTING, its OK, but I want to use tables
and PREROUTING, POSTROUTING as well in script as at prompt. I cannot do
this.

Suggestions ??

 -Johan-