Could anyone kindly provide the commands to completely reset the iptables (firewall) for Ubuntu 12.04 to its default "factory" setting? From what I understand, doing this wrong would cause one to be locked out of the linux box?
Set the default policy on the iptables to ACCEPT:
iptables -P INPUT ACCEPT iptables -P OUTPUT ACCEPT iptables -P FORWARD ACCEPT
Then flush the rules:
iptables -F INPUT iptables -F OUTPUT iptables -F FORWARD
Note, this will not affect alternate tables, NAT tables, PRE/POST routing tables, etc.
This thing seem to be ok.. http://insanelabs.com/linux/linux-reset-iptables-firewall-rules/
iptables -F iptables -X iptables -t nat -F iptables -t nat -X iptables -t mangle -F iptables -t mangle -X iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT
Wing's answer will be at your rescue when things go wrong with
iptables. If you want to reset everything, including alternate tables,
PRE/POST ROUTING, use this script:
#!/bin/sh # # rc.flush-iptables - Resets iptables to default values. # # Copyright (C) 2001 Oskar Andreasson <bluefluxATkoffeinDOTnet> # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; version 2 of the License. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program or from the site that you downloaded it # from; if not, write to the Free Software Foundation, Inc., 59 Temple # Place, Suite 330, Boston, MA 02111-1307 USA # # Configurations # IPTABLES="/sbin/iptables" # # reset the default policies in the filter table. # $IPTABLES -P INPUT ACCEPT $IPTABLES -P FORWARD ACCEPT $IPTABLES -P OUTPUT ACCEPT # # reset the default policies in the nat table. # $IPTABLES -t nat -P PREROUTING ACCEPT $IPTABLES -t nat -P POSTROUTING ACCEPT $IPTABLES -t nat -P OUTPUT ACCEPT # # reset the default policies in the mangle table. # $IPTABLES -t mangle -P PREROUTING ACCEPT $IPTABLES -t mangle -P POSTROUTING ACCEPT $IPTABLES -t mangle -P INPUT ACCEPT $IPTABLES -t mangle -P OUTPUT ACCEPT $IPTABLES -t mangle -P FORWARD ACCEPT # # flush all the rules in the filter and nat tables. # $IPTABLES -F $IPTABLES -t nat -F $IPTABLES -t mangle -F # # erase all chains that's not default in filter and nat table. # $IPTABLES -X $IPTABLES -t nat -X $IPTABLES -t mangle -X