# ----------------------------------------------------------------------------
# GIPTables Firewall v1.1 http://www.giptables.org
# Copyright (C) 2002 Adrian Pascalau <apascalau@openna.com>
# NTP module
#
# ----------------------------------------------------------------------------
# This file is part of GIPTables Firewall
#
# GIPTables Firewall 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; either version 2 of the License, or
# (at your option) any later version.
#
# 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; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# ----------------------------------------------------------------------------
# About NTP

# ntp             123/udp                         # Network Time Protocol

NTP_PORT="123"

# ----------------------------------------------------------------------------
# accept_ntp_request
# Usage: accept_ntp_request chain ntp_client_ipaddr ntp_server_ipaddr
#

accept_ntp_request ()
{
    local chain=$1
    local ntp_client_ipaddr=$2
    local ntp_server_ipaddr=$3

    $IPTABLES -A $chain -p udp \
              -s $ntp_client_ipaddr --sport $UNPRIV_PORTS \
              -d $ntp_server_ipaddr --dport $NTP_PORT \
              -m state --state NEW,ESTABLISHED \
              -j ACCEPT
    return 0
}

# ----------------------------------------------------------------------------
# accept_ntp_reply
# Usage: accept_ntp_reply chain ntp_server_ipaddr ntp_client_ipaddr
#

accept_ntp_reply ()
{
    local chain=$1
    local ntp_server_ipaddr=$2
    local ntp_client_ipaddr=$3

    $IPTABLES -A $chain -p udp \
              -s $ntp_server_ipaddr --sport $NTP_PORT \
              -d $ntp_client_ipaddr --dport $UNPRIV_PORTS \
              -m state --state ESTABLISHED \
              -j ACCEPT

    return 0
}