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Full Discussion: Editing rules on iptables
Special Forums Cybersecurity Editing rules on iptables Post 302526019 by garric on Monday 30th of May 2011 05:11:12 AM
Old 05-30-2011
Editing rules on iptables

Hello,

I was playing around with iptables to setup an isolated system. On a SLES10 system, I ran the below to setup my first draft of rules. I noticed that the rules come into effect immediately and do not require any restart of iptables.

Code:
iptables -A INPUT -j ACCEPT
iptables -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -j ACCEPT -p tcp --dport 80 -d xx.xx.xx.xx

iptables -A OUTPUT -o lo -j ACCEPT
iptables -P OUTPUT DROP

Now, I want to add a new rule in the middle (lets say, open outbound communication on port 500 for ip yy.yy.yy.yy). But since the rules are evaluated sequentially, it will become effective after my last rule (which is iptables -P OUTPUT DROP). Since all packets match this default rule for output, I cannot add a new rule without rebooting the machine.

I wanted to know if there is a way to introduce new rules without having to reboot a machine, ie introduce a rule above the 'iptables -P OUTPUT DROP'. Any help or leads into documentation will help.

Last edited by pludi; 05-30-2011 at 09:06 AM..
 

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IPTABLES-SAVE(8)                                                  iptables 1.6.1                                                  IPTABLES-SAVE(8)

NAME
iptables-save -- dump iptables rules to stdout ip6tables-save -- dump iptables rules to stdout SYNOPSIS
iptables-save [-M modprobe] [-c] [-t table] ip6tables-save [-M modprobe] [-c] [-t table] DESCRIPTION
iptables-save and ip6tables-save are used to dump the contents of IP or IPv6 Table in easily parseable format to STDOUT. Use I/O-redirect- ion provided by your shell to write to a file. -M, --modprobe modprobe_program Specify the path to the modprobe program. By default, iptables-save will inspect /proc/sys/kernel/modprobe to determine the exe- cutable's path. -c, --counters include the current values of all packet and byte counters in the output -t, --table tablename restrict output to only one table. If not specified, output includes all available tables. BUGS
None known as of iptables-1.2.1 release AUTHORS
Harald Welte <laforge@gnumonks.org> Rusty Russell <rusty@rustcorp.com.au> Andras Kis-Szabo <kisza@sch.bme.hu> contributed ip6tables-save. SEE ALSO
iptables-apply(8),iptables-restore(8), iptables(8) The iptables-HOWTO, which details more iptables usage, the NAT-HOWTO, which details NAT, and the netfilter-hacking-HOWTO which details the internals. iptables 1.6.1 IPTABLES-SAVE(8)
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