Hi every one,
I am running a server with Redhat 8.0 on it
I want to setup iptables firewalls on it, using this config file.
But to do it, I would need some explination on some of the
main code line of the script below
Please any help would be appreciated.
PS- If you know a place(websyte) where I can have some explanations on the
codes lines, I would be glad too.
Junior
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#!/bin/sh
#
# Startup script to implement /etc/sysconfig/iptables pre-defined rules.
#
# chkconfig: 2345 08 92
#
# description: Automates a packet filtering firewall with iptables.
#
# by
bero@redhat.com, based on the ipchains script:
# Script Author: Joshua Jensen <joshua@redhat.com>
# -- hacked up by gafton with help from notting
# modified by Anton Altaparmakov <aia21@cam.ac.uk>:
# modified by Nils Philippsen <nils@redhat.de>
#
# config: /etc/sysconfig/iptables
# Source 'em up
. /etc/init.d/functions
IPTABLES_CONFIG=/etc/sysconfig/iptables
if [ ! -x /sbin/iptables ]; then
exit 0
fi
KERNELMAJ=`uname -r | sed -e 's,\..*,,'`
KERNELMIN=`uname -r | sed -e 's,[^\.]*\.,,' -e 's,\..*,,'`
if [ "$KERNELMAJ" -lt 2 ] ; then
exit 0
fi
if [ "$KERNELMAJ" -eq 2 -a "$KERNELMIN" -lt 3 ] ; then
exit 0
fi
if /sbin/lsmod 2>/dev/null |grep -q ipchains ; then
# Don't do both
exit 0
fi
start() {
# don't do squat if we don't have the config file
if [ -f $IPTABLES_CONFIG ]; then
# If we don't clear these first, we might be adding to
# pre-existing rules.
action $"Flushing all current rules and user defined chains:" iptables -F
action $"Clearing all current rules and user defined chains:" iptables -X
chains=`cat /proc/net/ip_tables_names 2>/dev/null`
for i in $chains; do iptables -t $i -F; done && \
success $"Flushing all current rules and user defined chains:" || \
failure $"Flushing all current rules and user defined chains:"
for i in $chains; do iptables -t $i -X; done && \
success $"Clearing all current rules and user defined chains:" || \
failure $"Clearing all current rules and user defined chains:"
for i in $chains; do iptables -t $i -Z; done
echo $"Applying iptables firewall rules: "
grep -v "^:space:*#" $IPTABLES_CONFIG | grep -v '^:space:*$' | /sbin/iptables-restore -c && \
success $"Applying iptables firewall rules" || \
failure $"Applying iptables firewall rules"
echo
touch /var/lock/subsys/iptables
fi
}
stop() {
chains=`cat /proc/net/ip_tables_names 2>/dev/null`
for i in $chains; do iptables -t $i -F; done && \
success $"Flushing all chains:" || \
failure $"Flushing all chains:"
for i in $chains; do iptables -t $i -X; done && \
success $"Removing user defined chains:" || \
failure $"Removing user defined chains:"
echo -n $"Resetting built-in chains to the default ACCEPT policy:"
iptables -P INPUT ACCEPT && \
iptables -P OUTPUT ACCEPT && \
iptables -P FORWARD ACCEPT && \
iptables -t nat -P PREROUTING ACCEPT && \
iptables -t nat -P POSTROUTING ACCEPT && \
iptables -t nat -P OUTPUT ACCEPT && \
iptables -t mangle -P PREROUTING ACCEPT && \
iptables -t mangle -P OUTPUT ACCEPT && \
success $"Resetting built-in chains to the default ACCEPT policy" || \
failure $"Resetting built-in chains to the default ACCEPT policy"
echo
rm -f /var/lock/subsys/iptables
}
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
# "restart" is really just "start" as this isn't a daemon,
# and "start" clears any pre-defined rules anyway.
# This is really only here to make those who expect it happy
start
;;
condrestart)
[ -e /var/lock/subsys/iptables ] && start
;;
status)
echo $"Table: filter"
iptables --list
echo $"Table: nat"
iptables -t nat --list
echo $"Table: mangle"
iptables -t mangle --list
;;
panic)
echo -n $"Changing target policies to DROP: "
iptables -P INPUT DROP && \
iptables -P FORWARD DROP && \
iptables -P OUTPUT DROP && \
iptables -t nat -P PREROUTING DROP && \
iptables -t nat -P POSTROUTING DROP && \
iptables -t nat -P OUTPUT DROP && \
iptables -t mangle -P PREROUTING DROP && \
iptables -t mangle -P OUTPUT DROP && \
success $"Changing target policies to DROP" || \
failure $"Changing target policies to DROP"
echo
iptables -F INPUT && \
iptables -F FORWARD && \
iptables -F OUTPUT && \
iptables -t nat -F PREROUTING && \
iptables -t nat -F POSTROUTING && \
iptables -t nat -F OUTPUT && \
iptables -t mangle -F PREROUTING && \
iptables -t mangle -F OUTPUT && \
success $"Flushing all chains:" || \
failure $"Flushing all chains:"
iptables -X INPUT && \
iptables -X FORWARD && \
iptables -X OUTPUT && \
iptables -t nat -X PREROUTING && \
iptables -t nat -X POSTROUTING && \
iptables -t nat -X OUTPUT && \
iptables -t mangle -X PREROUTING && \
iptables -t mangle -X OUTPUT && \
success $"Removing user defined chains:" || \
failure $"Removing user defined chains:"
;;
save)
echo -n $"Saving current rules to $IPTABLES_CONFIG: "
touch $IPTABLES_CONFIG
chmod 600 $IPTABLES_CONFIG
/sbin/iptables-save -c > $IPTABLES_CONFIG 2>/dev/null && \
success $"Saving current rules to $IPTABLES_CONFIG" || \
failure $"Saving current rules to $IPTABLES_CONFIG"
echo
;;
*)
echo $"Usage: $0 {start|stop|restart|condrestart|status|panic|save}"
exit 1
esac
exit 0
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etc/sysconfig/iptables file explinations
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