LINUX HELP ALL

MRKAVANA (mrkavana@gmail.com) - www.facebook.com/kavanathai

Oct 12, 2011

Mount SAN's Partition over Fiber cable for Linux

multipath -ll
fdisk -l
echo "1" > /sys/class/fc_host/host0/issue_lip
echo "1" > /sys/class/fc_host/host1/issue_lip
multipath -ll
fdisk -l
multipath -ll
pvcreate /dev/mapper/mpath4
pvdisplay
vgcreate vglog_file /dev/mapper/mpath4
lvcreate -L 100G vglog_file -n lvlog_file
lvcreate -L 99G vglog_file -n lvlog_file
mkfs.ext3 /dev/mapper/vglog_file-lvlog_file
mkdir logfile
mount -t ext3 /dev/mapper/vglog_file-lvlog_file /logfile/
chown sysadmin:root logfile/
echo "/dev/mapper/vglog_file-lvlog_file /logfile/ ext3 defaults 1 2">>/etc/fstab

Oct 6, 2011

Steve Jobs Memorial

We were very loved - We will be very missed; Thank you Steve!

Oct 3, 2011

Install and configure SNMP on RHEL or CentOS

This guide describe howto install and do a basic configure of SNMP on a RedHat Enterprise Linux or CentOS. Probably it will work on many other *nix systems.

1. Installation

Run command yum install net-snmp-utils

[root@dull etc]# yum install net-snmp-utils
Loading "fastestmirror" plugin
Loading "dellsysidplugin" plugin
...
...
Dependencies Resolved

=============================================================================
 Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
 net-snmp-utils          i386       1:5.3.1-24.el5_2.2  updates           182 k
Installing for dependencies:
 net-snmp                i386       1:5.3.1-24.el5_2.2  updates           698 k

Transaction Summary
=============================================================================
Install      2 Package(s)
Update       0 Package(s)
Remove       0 Package(s)

Total download size: 879 k
Is this ok [y/N]: y

Answer y

Downloading Packages:

(1/2): net-snmp-utils-5.3 100% |=========================| 182 kB    00:02
(2/2): net-snmp-5.3.1-24. 100% |=========================| 698 kB    00:06
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
 Installing: net-snmp                     ######################### [1/2]
  Installing: net-snmp-utils               ######################### [2/2]
Installed: net-snmp-utils.i386 1:5.3.1-24.el5_2.2
Dependency Installed: net-snmp.i386 1:5.3.1-24.el5_2.2
Complete!

Now it is installed

2. Configure

I’m careful so I do a backup of the snmpd config file.

[root@dull ~]# mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.org

Create a new config file.

[root@dull ~]# vi /etc/snmp/snmpd.conf

rocommunity  public
syslocation  "PDC, Peters DataCenter"
syscontact  peter@it-slav.net

Start the snmpd service

[root@dull ~]# /etc/init.d/snmpd start

Do a snmpwalk to make sure it is working

[root@dull ~]# snmpwalk -v 1 -c public -O e 127.0.0.1
SNMPv2-MIB::sysDescr.0 = STRING: Linux dull 2.6.18-92.1.17.el5 #1 SMP Tue Nov 4 13:45:01 EST 2008 i686
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-MIB::netSnmpAgentOIDs.10
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (16748) 0:02:47.48
SNMPv2-MIB::sysContact.0 = STRING: peter@it-slav.net
SNMPv2-MIB::sysName.0 = STRING: dull
SNMPv2-MIB::sysLocation.0 = STRING: "PDC, Peters DataCentral"
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (1) 0:00:00.01
...

...

Yes, it is working

And finally, make sure snmpd starts next time you restart your machine.

[root@dull ~]# chkconfig snmpd on

3. Monitor example

Below is an example of how it looks using op5 Monitor a Nagios based Enterprise Monitor solution.

4. Useful links

op5 Statistics, a cacti based graph tool
op5 Monitor, an Enterprise Class Monitoring system based on Nagios
Net-SNMP, an open source implementation of SNMP
Cacti, an open source graph tool
Nagios, the number 1 monitor tool

Sep 23, 2011

Script IPTABLES for WEB server firewall

Script IPTABLES for Mail server firewall

#!/bin/sh
#
# ----------------------------------------------------------------------------
# Last modified by Gerhard Mourani: 10-10-2000
# ----------------------------------------------------------------------------
# Copyright (C) 1997, 1998, 1999 Robert L. Ziegler
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for educational, research, private and non-profit purposes,
# without fee, and without a written agreement is hereby granted.
# This software is provided as an example and basis for individual firewall
# development. This software is provided without warranty.
#
# Any material furnished by Robert L. Ziegler is furnished on an
# "as is" basis. He makes no warranties of any kind, either expressed
# or implied as to any matter including, but not limited to, warranty
# of fitness for a particular purpose, exclusivity or results obtained
# from use of the material.
# ----------------------------------------------------------------------------
#
# Invoked from /etc/rc.d/init.d/firewall.
# chkconfig: - 60 95
# description: Starts and stops the IPCHAINS Firewall \
# used to provide Firewall network services.

# Source function library.
. /etc/rc.d/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

# Check that networking is up.
if [ ${NETWORKING} = "no" ]
then
exit 0
fi

if [ ! -x /sbin/ipchains ]; then
exit 0
fi

# See how we were called.
case "$1" in
start)
echo -n "Starting Firewalling Services: "

# Some definitions for easy maintenance.

# ----------------------------------------------------------------------------
# EDIT THESE TO SUIT YOUR SYSTEM AND ISP.

EXTERNAL_INTERFACE="eth0" # Internet connected interface
LOCAL_INTERFACE_1="eth1" # Internal LAN interface
LOOPBACK_INTERFACE="lo" # Your local naming convention
IPADDR="my.ip.address" # Your IP address
LOCALNET_1="192.168.1.0/24" # Whatever private range you use
IPSECSG="my.ipsecsg.address" # Space separated list of remote VPN gateways
FREESWANVI="ipsec0" # Space separated list of virtual interfaces
ANYWHERE="any/0" # Match any IP address
NAMESERVER_1="my.name.server.1" # Everyone must have at least one
NAMESERVER_2="my.name.server.2" # Your secondary name server

SMTP_SERVER="my.smtp.server" # Your Mail Hub Server.
POP_SERVER="my.pop.server" # External pop server, if any
NEWS_SERVER="my.news.server" # External news server, if any
SYSLOG_SERVER="syslog.internal.server" # Your syslog internal server

LOOPBACK="127.0.0.0/8" # Reserved loopback address range
CLASS_A="10.0.0.0/8" # Class A private networks
CLASS_B="172.16.0.0/12" # Class B private networks
CLASS_C="192.168.0.0/16" # Class C private networks
CLASS_D_MULTICAST="224.0.0.0/4" # Class D multicast addresses
CLASS_E_RESERVED_NET="240.0.0.0/5" # Class E reserved addresses
BROADCAST_SRC="0.0.0.0" # Broadcast source address
BROADCAST_DEST="255.255.255.255" # Broadcast destination address
PRIVPORTS="0:1023" # Well known, privileged port range
UNPRIVPORTS="1024:65535" # Unprivileged port range

# ----------------------------------------------------------------------------

# SSH starts at 1023 and works down to 513 for
# each additional simultaneous incoming connection.
SSH_PORTS="1022:1023" # range for SSH privileged ports

# traceroute usually uses -S 32769:65535 -D 33434:33523
TRACEROUTE_SRC_PORTS="32769:65535"
TRACEROUTE_DEST_PORTS="33434:33523"

# ----------------------------------------------------------------------------
# Default policy is DENY
# Explicitly accept desired INCOMING & OUTGOING connections

# Remove all existing rules belonging to this filter
ipchains -F

# Clearing all current rules and user defined chains
ipchains -X

# Set the default policy of the filter to deny.
# Don't even bother sending an error message back.
ipchains -P input DENY
ipchains -P output DENY
ipchains -P forward DENY

# set masquerade timeout to 10 hours for tcp connections
ipchains -M -S 36000 0 0

# Don't forward fragments. Assemble before forwarding.
ipchains -A output -f -i $LOCAL_INTERFACE_1 -j DENY

# ----------------------------------------------------------------------------
# MODULES MASQUERADING
# Uncomment bellow all modules lines that you need

# These modules are necessary to masquerade their respective services.
/sbin/modprobe ip_masq_ftp
/sbin/modprobe ip_masq_raudio ports=554,7070,7071,6970,6971
/sbin/modprobe ip_masq_irc
#/sbin/modprobe ip_masq_vdolive
#/sbin/modprobe ip_masq_cuseeme
#/sbin/modprobe ip_masq_quake

# ----------------------------------------------------------------------------
# LOOPBACK

# Unlimited traffic on the loopback interface.
ipchains -A input -i $LOOPBACK_INTERFACE -j ACCEPT
ipchains -A output -i $LOOPBACK_INTERFACE -j ACCEPT

# ----------------------------------------------------------------------------
# Network Ghouls
# Deny access to jerks

# /etc/rc.d/rc.firewall.blocked contains a list of
# ipchains -A input -i $EXTERNAL_INTERFACE -s address -j DENY
# rules to block from any access.

# Refuse any connection from problem sites
#if [ -f /etc/rc.d/rc.firewall.blocked ]; then
# . /etc/rc.d/rc.firewall.blocked
#fi

# ----------------------------------------------------------------------------
# SPOOFING & BAD ADDRESSES
# Refuse spoofed packets.
# Ignore blatantly illegal source addresses.
# Protect yourself from sending to bad addresses.

# Refuse incoming packets pretending to be from the external address.
ipchains -A input -s $IPADDR -j DENY -l

# Refuse incoming packets claiming to be from a Class A, B or C private network
ipchains -A input -s $CLASS_A -j DENY
ipchains -A input -s $CLASS_B -j DENY
# ipchains -A input -s $CLASS_C -j DENY

# Refuse broadcast address SOURCE packets
ipchains -A input -s $BROADCAST_DEST -j DENY -l
ipchains -A input -d $BROADCAST_SRC -j DENY -l

# Refuse Class D multicast addresses
# Multicast is illegal as a source address.
# Multicast uses UDP.
ipchains -A input -s $CLASS_D_MULTICAST -j DENY

# Refuse Class E reserved IP addresses
ipchains -A input -s $CLASS_E_RESERVED_NET -j DENY -l

# Refuse addresses defined as reserved by the IANA.
# Note: this list includes the loopback, multicast, & reserved addresses.
# The following are based on reservations as listed by IANA as of 10/10/2000.
# Please regularly check at http://www.iana.org/ for the latest status.

# 0.*.*.* - Can't be blocked for DHCP users.
# 1.*.*.*, 2.*.*.*, 5.*.*.*, 7.*.*.*, 23.*.*.*, 27.*.*.*
# 31.*.*.*, 36.*.*.*, 37.*.*.*, 39.*.*.*, 41.*.*.*, 42.*.*.*
# 49-50.*.*.*, 58-60.*.*.*
# 67-127.*.*.*
# 169.254.*.* - Link Local Networks
# 192.0.2.* - TEST-NET
# 197.*.*.*, 217-255.*.*.*

ipchains -A input -s 0.0.0.0/8 -j DENY -l
ipchains -A input -s 1.0.0.0/8 -j DENY -l
ipchains -A input -s 2.0.0.0/8 -j DENY -l
ipchains -A input -s 5.0.0.0/8 -j DENY -l
ipchains -A input -s 7.0.0.0/8 -j DENY -l
ipchains -A input -s 23.0.0.0/8 -j DENY -l
ipchains -A input -s 27.0.0.0/8 -j DENY -l
ipchains -A input -s 31.0.0.0/8 -j DENY -l
ipchains -A input -s 36.0.0.0/8 -j DENY -l
ipchains -A input -s 37.0.0.0/8 -j DENY -l
ipchains -A input -s 39.0.0.0/8 -j DENY -l
ipchains -A input -s 41.0.0.0/8 -j DENY -l
ipchains -A input -s 42.0.0.0/8 -j DENY -l
ipchains -A input -s 49.0.0.0/8 -j DENY -l
ipchains -A input -s 50.0.0.0/8 -j DENY -l
ipchains -A input -s 58.0.0.0/7 -j DENY -l
ipchains -A input -s 60.0.0.0/8 -j DENY -l
ipchains -A input -s 67.0.0.0/8 -j DENY -l
ipchains -A input -s 68.0.0.0/6 -j DENY -l
ipchains -A input -s 72.0.0.0/5 -j DENY -l
ipchains -A input -s 80.0.0.0/4 -j DENY -l
ipchains -A input -s 96.0.0.0/3 -j DENY -l
ipchains -A input -s 169.254.0.0/16 -j DENY -l
ipchains -A input -s 192.0.2.0/24 -j DENY -l
ipchains -A input -s 197.0.0.0/8 -j DENY -l
ipchains -A input -s 218.0.0.0/7 -j DENY -l
ipchains -A input -s 220.0.0.0/6 -j DENY -l
ipchains -A input -s 224.0.0.0/3 -j DENY -l

# ----------------------------------------------------------------------------
# ICMP

# To prevent denial of service attacks based on ICMP bombs, filter
# incoming Redirect (5) and outgoing Destination Unreachable (3).
# Note, however, disabling Destination Unreachable (3) is not
# advisable, as it is used to negotiate packet fragment size.

# For bi-directional ping.
# Message Types: Echo_Reply (0), Echo_Request (8)
# To prevent attacks, limit the src addresses to your ISP range.
#
# For outgoing traceroute.
# Message Types: INCOMING Dest_Unreachable (3), Time_Exceeded (11)
# default UDP base: 33434 to base+nhops-1
#
# For incoming traceroute.
# Message Types: OUTGOING Dest_Unreachable (3), Time_Exceeded (11)
# To block this, deny OUTGOING 3 and 11

# 0: echo-reply (pong)
# 3: destination-unreachable, port-unreachable, fragmentation-needed, etc.
# 4: source-quench
# 5: redirect
# 8: echo-request (ping)
# 11: time-exceeded
# 12: parameter-problem

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type echo-reply \
-d $IPADDR -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type destination-unreachable \
-d $IPADDR -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type source-quench \
-d $IPADDR -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type time-exceeded \
-d $IPADDR -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type parameter-problem \
-d $IPADDR -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p icmp \
-s $IPADDR fragmentation-needed -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p icmp \
-s $IPADDR source-quench -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p icmp \
-s $IPADDR echo-request -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p icmp \
-s $IPADDR parameter-problem -j ACCEPT

# ----------------------------------------------------------------------------
# UDP INCOMING TRACEROUTE
# traceroute usually uses -S 32769:65535 -D 33434:33523

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $MY_ISP $TRACEROUTE_SRC_PORTS \
-d $IPADDR $TRACEROUTE_DEST_PORTS -j ACCEPT -l

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $ANYWHERE $TRACEROUTE_SRC_PORTS \
-d $IPADDR $TRACEROUTE_DEST_PORTS -j DENY -l

# ----------------------------------------------------------------------------
# DNS server
# ----------

# DNS: full server
# server/client to server query or response

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $ANYWHERE $UNPRIVPORTS \
-d $IPADDR 53 -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR 53 \
-d $ANYWHERE $UNPRIVPORTS -j ACCEPT

# DNS client (53)
# ---------------
ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $NAMESERVER_1 53 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR $UNPRIVPORTS \
-d $NAMESERVER_1 53 -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $NAMESERVER_2 53 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR $UNPRIVPORTS \
-d $NAMESERVER_2 53 -j ACCEPT

# TCP client to server requests are allowed by the protocol
# if UDP requests fail. This is rarely seen. Usually, clients
# use TCP as a secondary nameserver for zone transfers from
# their primary nameservers, and as hackers.

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $NAMESERVER_1 53 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $NAMESERVER_1 53 -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $NAMESERVER_2 53 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $NAMESERVER_2 53 -j ACCEPT

# ----------------------------------------------------------------------------
# TCP accept only on selected ports
# ---------------------------------
# ------------------------------------------------------------------

# SSH server (22)
# ---------------

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp \
-s $ANYWHERE $UNPRIVPORTS \
-d $IPADDR 22 -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $IPADDR 22 \
-d $ANYWHERE $UNPRIVPORTS -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp \
-s $ANYWHERE $SSH_PORTS \
-d $IPADDR 22 -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $IPADDR 22 \
-d $ANYWHERE $SSH_PORTS -j ACCEPT

# SSH client (22)
# ---------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 22 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 22 -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 22 \
-d $IPADDR $SSH_PORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $SSH_PORTS \
-d $ANYWHERE 22 -j ACCEPT

# ------------------------------------------------------------------

# HTTP client (80)
# ----------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 80 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 80 -j ACCEPT

# ------------------------------------------------------------------

# HTTPS client (443)
# ------------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 443 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 443 -j ACCEPT

# ------------------------------------------------------------------

# POP client (110)
# ----------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $POP_SERVER 110 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $POP_SERVER 110 -j ACCEPT

# ------------------------------------------------------------------

# NNTP NEWS client (119)
# ----------------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $NEWS_SERVER 119 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $NEWS_SERVER 119 -j ACCEPT

# ------------------------------------------------------------------

# FINGER client (79)
# ------------------
# ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
# -s $ANYWHERE 79 \
# -d $IPADDR $UNPRIVPORTS -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
# -s $IPADDR $UNPRIVPORTS \
# -d $ANYWHERE 79 -j ACCEPT

# ------------------------------------------------------------------

# SYSLOG client (514)
# -----------------

# ipchains -A output -i $LOCAL_INTERFACE_1 -p udp \
# -s $IPADDR 514 \
# -d $SYSLOG_SERVER 514 -j ACCEPT

# ------------------------------------------------------------------

# AUTH server (113)
# -----------------

# Reject, rather than deny, the incoming auth port. (NET-3-HOWTO)

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp \
-s $ANYWHERE \
-d $IPADDR 113 -j REJECT

# AUTH client (113)
# -----------------
# ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
# -s $ANYWHERE 113 \
# -d $IPADDR $UNPRIVPORTS -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
# -s $IPADDR $UNPRIVPORTS \
# -d $ANYWHERE 113 -j ACCEPT

# ------------------------------------------------------------------

# SMTP client (25)
# ----------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 25 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 25 -j ACCEPT

# ------------------------------------------------------------------

# IRC client (6667)
# -----------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 6667 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 6667 -j ACCEPT

# ------------------------------------------------------------------

# ICQ client (4000)
# -----------------
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 2000:4000 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 2000:4000 -j ACCEPT

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $ANYWHERE 4000 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 4000 -j ACCEPT

# ------------------------------------------------------------------

# FTP client (20, 21)
# -------------------

# outgoing request
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 21 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 21 -j ACCEPT

# NORMAL mode data channel
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp \
-s $ANYWHERE 20 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

# NORMAL mode data channel responses
ipchains -A output -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 20 -j ACCEPT

# PASSIVE mode data channel creation
ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE $UNPRIVPORTS -j ACCEPT

# PASSIVE mode data channel responses
ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE $UNPRIVPORTS \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

# ------------------------------------------------------------------

# RealAudio / QuickTime client
# ----------------------------

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 554 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 554 -j ACCEPT

# TCP is a more secure method: 7070:7071

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
-s $ANYWHERE 7070:7071 \
-d $IPADDR $UNPRIVPORTS -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE 7070:7071 -j ACCEPT

# UDP is the preferred method: 6970:6999
# For LAN machines, UDP requires the RealAudio masquerading module and
# the ipmasqadm third-party software.

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
-s $ANYWHERE $UNPRIVPORTS \
-d $IPADDR 6970:6999 -j ACCEPT

ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR $UNPRIVPORTS \
-d $ANYWHERE $UNPRIVPORTS -j ACCEPT

# ------------------------------------------------------------------

# WHOIS client (43)
# -----------------
# ipchains -A input -i $EXTERNAL_INTERFACE -p tcp ! -y \
# -s $ANYWHERE 43 \
# -d $IPADDR $UNPRIVPORTS -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p tcp \
# -s $IPADDR $UNPRIVPORTS \
# -d $ANYWHERE 43 -j ACCEPT

# ------------------------------------------------------------------

# OUTGOING TRACEROUTE
# -------------------
ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
-s $IPADDR $TRACEROUTE_SRC_PORTS \
-d $ANYWHERE $TRACEROUTE_DEST_PORTS -j ACCEPT

# ----------------------------------------------------------------------------
# Unlimited traffic within the local network.

# All internal machines have access to the firewall machine.

ipchains -A input -i $LOCAL_INTERFACE_1 -s $LOCALNET_1 -j ACCEPT
ipchains -A output -i $LOCAL_INTERFACE_1 -d $LOCALNET_1 -j ACCEPT

# ----------------------------------------------------------------------------
# FreeS/WAN IPSec VPN
# -------------------

# If you are using the FreeSWAN IPSec VPN, you will need to fill in the
# addresses of the gateways in the IPSECSG and the virtual interfaces for
# FreeS/Wan IPSEC in the FREESWANVI parameters. Look at the beginning of
# this firewall script rules file to set the parameters.

# IPSECSG is a Space separated list of remote gateways. FREESWANVI is a
# Space separated list of virtual interfaces for FreeS/Wan IPSEC
# implementation. Only include those that are actually used.

# Allow IPSEC protocol from remote gateways on external interface
# IPSEC uses three main types of packet:
# IKE uses the UDP protocol and port 500,
# ESP use the protocol number 50, and
# AH use the protocol number 51

# ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
# -s $IPSECSG -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p udp \
# -d $IPSECSG -j ACCEPT

# ipchains -A input -i $EXTERNAL_INTERFACE -p 50 \
# -s $IPSECSG -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p 50 \
# -d $IPSECSG -j ACCEPT

# ipchains -A input -i $EXTERNAL_INTERFACE -p 51 \
# -s $IPSECSG -j ACCEPT

# ipchains -A output -i $EXTERNAL_INTERFACE -p 51 \
# -d $IPSECSG -j ACCEPT

# Allow all traffic to FreeS/WAN Virtual Interface
# ipchains -A input -i $FREESWANVI \
# -s $ANYWHERE \
# -d $ANYWHERE -j ACCEPT

# ipchains -A output -i $FREESWANVI \
# -s $ANYWHERE \
# -d $ANYWHERE -j ACCEPT

# Forward anything from the FreeS/WAN virtual interface IPSEC tunnel
# ipchains -A forward -i $FREESWANVI \
# -s $ANYWHERE \
# -d $ANYWHERE -j ACCEPT

# Disable IP spoofing protection to allow IPSEC to work properly
# echo 0 > /proc/sys/net/ipv4/conf/ipsec0/rp_filter
# echo 0 > /proc/sys/net/ipv4/conf/eth0/rp_filter

# ----------------------------------------------------------------------------
# Masquerade internal traffic.

# All internal traffic is masqueraded externally.

ipchains -A forward -i $EXTERNAL_INTERFACE -s $LOCALNET_1 -j MASQ

# ----------------------------------------------------------------------------
# Enable logging for selected denied packets

ipchains -A input -i $EXTERNAL_INTERFACE -p tcp -j DENY -l

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
--destination-port $PRIVPORTS -j DENY -l

ipchains -A input -i $EXTERNAL_INTERFACE -p udp \
--destination-port $UNPRIVPORTS -j DENY -l

ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type 5 -j DENY -l
ipchains -A input -i $EXTERNAL_INTERFACE -p icmp \
--icmp-type 13:255 -j DENY -l

ipchains -A output -i $EXTERNAL_INTERFACE -j REJECT -l

# ----------------------------------------------------------------------------

;;
stop)
echo -n "Shutting Firewalling Services: "

# Remove all existing rules belonging to this filter
ipchains -F

# Delete all user-defined chain to this filter
ipchains -X

# Reset the default policy of the filter to accept.
ipchains -P input ACCEPT
ipchains -P output ACCEPT
ipchains -P forward ACCEPT

;;
status)
status firewall
;;
restart|reload)
$0 stop
$0 start
;;
*)
echo "Usage: firewall {start|stop|status|restart|reload}"
exit 1
esac

exit 0