FreeBSD / One ISP / Two and more xDSL/internet channels / Load balancing

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Load Balancing

Description

Load balancing between multiple ISP's in case if there is no BGP/OSPF/RIP can be achieved by using following software:

  1. FreeBSD as base system;
  2. IPFW firewall;
  3. Optional MPD5 as PPPoE client.

How it all works?

Current config:

FIB 0: ADSL PPPOE
FIB 1: ADSL PPPOE
FIB 2: DHCP client
  • DHCP client on FIB starts via RC.D script (see below);
  • watchdog script periodically check's FIB 2 connection and reload rules on status change(see below);
  • PPPOE connections managed by MPD5 daemon;;
  • When connection established "/usr/local/etc/mpd5/up-script_fib_X.sh" script will be executed in order to reload firewall rules;
  • If one or more PPPoE connection lost MPD5 will DOWN adsl interface and execute "/usr/local/etc/mpd5/down-script_fib_X.sh" script in order to reload firewall rules;
  • arpalert daemon waits for new MAC's to appear and launches script which will put IP's to IPFW tables. This is actual load balancing.

Why configuration is so complicated?

If we use simple 'prob' and 'setfib' rules of IPFW some services may work incorrect(FTP, PPTP, HTTPS and etc.).

Configuration

IPFW firewall

Kernel options:

options         LIBALIAS
options         ROUTETABLES=5
options         IPFIREWALL
options         IPDIVERT
options         DUMMYNET
options         IPFIREWALL_NAT
options         IPFIREWALL_FORWARD
options         IPFIREWALL_DEFAULT_TO_ACCEPT
options         IPFIREWALL_VERBOSE
options         IPFIREWALL_VERBOSE_LIMIT=50

/etc/sysctl.conf:

net.inet.ip.fw.autoinc_step=5
net.inet.ip.fw.one_pass=0
net.inet.ip.fw.verbose=1
net.inet.ip.fw.dyn_short_lifetime=25
net.inet.ip.fw.verbose_limit=1000000

/etc/firewall:

#!/bin/sh

DELAY=`/usr/bin/jot -r 1 0 9`

# Delay
echo "${DELAY} seconds delay..."
sleep ${DELAY} 

PIDS=`pgrep -f "/bin/sh /etc/firewall" | wc -l`

#Check if copy of process is already running:
if [ ${PIDS} -gt 1 ]; then
  echo "Another copy is already running."
  exit 1
fi

#Flush out list before we begin.
ipfw -q -f flush
ipfw -q -f nat flush
ipfw -q pipe flush
ipfw -q queue flush

################################################################################

#Set rules command prefix
cmd="ipfw -q"

pif0="adsl1"
pif0ip=`ifconfig $pif0 inet | grep inet | awk '{print $2}'`
pif0gw=`ifconfig $pif0 inet | grep inet | awk '{print $4}'`

pif1="adsl2"
pif1ip=`ifconfig $pif1 inet | grep inet | awk '{print $2}'`
pif1gw=`ifconfig $pif1 inet | grep inet | awk '{print $4}'`

pif2="vlan200"
pif2ip="10.61.168.231"
pif2gw="10.61.168.1"


if [ ! -z "$pif0ip" ]; then
  pif0status="UP"
  else
    pif0status="DOWN"
fi

if [ ! -z "$pif1ip" ]; then
  pif1status="UP"
  else
    pif1status="DOWN"
fi

if [ -f /vlan200.status ]; then
  pif2status=`cat /vlan200.status`
else
  pif2status="DOWN"
fi

# Override
#pif0status="DOWN"
#pif1status="DOWN"
#pif2status="DOWN"

################################################################################

$cmd add 100 allow ip from any to any via lo0
$cmd add     deny ip from any to 127.0.0.0/8
$cmd add     deny ip from 127.0.0.0/8 to any

$cmd add 1100 skipto 2040 ip from any to any out xmit $lif tagged 101 keep-state
$cmd add      skipto 2080 ip from any to any out xmit $lif tagged 102 keep-state
$cmd add      skipto 2100 ip from any to any out xmit $lif tagged 120 keep-state

$cmd add 1500 deny gre from 192.168.1.XXX to any // This rule will drop first GRE packet from PPTP SERVER when VPN initiates 

# Next few IF's will keep firewall rules consistent in cases if ISP connections will go down

if [ $pif0status == "UP" ] && [ $pif1status == "UP" ]; then 
  $cmd add 2000 skipto 2040 ip from table\(101\) to any in recv $lif // Smart Load balancing using arpalert 
  $cmd add      skipto 2080 ip from table\(102\) to any in recv $lif // Smart Load balancing using arpalert 
fi

if [ $pif2status == "UP" ]; then
  $cmd add      skipto 2100 ip from table\(120\) to any in recv $lif // Smart Load balancing using arpalert 
fi

if [ $pif0status == "UP" ]; then
  $cmd add 2040 setfib 0 ip from any to any via $lif keep-state
  $cmd add 2050 allow tag 101 ip from any to any via $lif
fi

if [ $pif1status == "UP" ]; then
  $cmd add 2080 setfib 1 ip from any to any via $lif keep-state
  $cmd add 2090 allow tag 102 ip from any to any via $lif
fi

if [ $pif2status == "UP" ]; then
  $cmd add 2100 setfib 2 ip from any to any via $lif keep-state
  $cmd add 2110 allow tag 120 ip from any to any via $lif
fi

################################################################################

$cmd add 3050 deny ip from any to 192.168.0.0/16 in recv $pifs
$cmd add      deny ip from 192.168.0.0/16 to any in recv $pifs
$cmd add      deny ip from any to 172.16.0.0/12 in recv $pifs
$cmd add      deny ip from 172.16.0.0/12 to any in recv $pifs
$cmd add      deny ip from any to 10.0.0.0/8 in recv $pifs
$cmd add      deny ip from 10.0.0.0/8 to any in recv $pifs
$cmd add      deny ip from any to 169.254.0.0/16 in recv $pifs
$cmd add      deny ip from 169.254.0.0/16 to any in recv $pifs

################################################################################

if [ $pif1status == "UP" ]; then
  $cmd add 11000 fwd $pif1gw all from $pif1ip to any via $pif0 // Send reply to necessary interface
fi

if [ $pif2status == "UP" ]; then
  $cmd add 11100 fwd $pif2gw all from $pif2ip to any via $pif0 // Send reply to necessary interface
fi

################################################################################

$cmd add 13000 skipto 31000 log ip from any to $pif0ip 22 in recv $pif0 // sshd
$cmd add       skipto 31000 log ip from any to $pif1ip 22 in recv $pif1 // sshd
$cmd add       skipto 31000 log ip from any to $pif2ip 22 in recv $pif2 // sshd
$cmd add       skipto 31000 log ip from any to $pif0ip 1723 in recv $pif0 // PPTP server
$cmd add       skipto 31000 log ip from any to $pif1ip 1723 in recv $pif1 // PPTP server
$cmd add       skipto 31000 log ip from any to $pif2ip 1723 in recv $pif2 // PPTP server
$cmd add       skipto 31000 gre from any to $pif0ip in recv $pif0 // PPTP server
$cmd add       skipto 31000 gre from any to $pif1ip in recv $pif1 // PPTP server
$cmd add       skipto 31000 gre from any to $pif2ip in recv $pif2 // PPTP server

################################################################################

if [ $pif0status == "UP" ]; then
  $cmd add 20000 deny log ip from any to any in via $pif0 setup // Reject and Log all setup of incoming connections from the outside 
  $cmd add       deny log ip from any to any in via $pif1 setup // Reject and Log all setup of incoming connections from the outside 
  $cmd add       deny log ip from any to any in via $pif2 setup // Reject and Log all setup of incoming connections from the outside 
fi

################################################################################

if [ $pif0status == "UP" ]; then
  $cmd nat 101 config if $pif0 same_ports reset \
			redirect_port tcp 192.168.1.XXX:1723 $pif0ip:1723 \
                        redirect_proto gre 192.168.1.XXX $pif0ip
fi

if [ $pif1status == "UP" ]; then
  $cmd nat 102 config if $pif1 same_ports reset \
			redirect_port tcp 192.168.1.XXX:1723 $pif1ip:1723 \
                        redirect_proto gre 192.168.1.XXX $pif1ip
fi

if [ $pif2status == "UP" ]; then
  $cmd nat 120 config if $pif2 same_ports reset \
			redirect_port tcp 192.168.1.XXX:1723 $pif2ip:1723 \
                        redirect_proto gre 192.168.1.XXX $pif2ip
fi

################################################################################

# NAT
if [ $pif0status == "UP" ]; then

  $cmd add 31000 nat 101 ip from any to any via $pif0 // $pif0 nat
  $cmd add       skipto 35000 tag 101 ip from any to any in recv $pif0
fi

if [ $pif1status == "UP" ]; then
  $cmd add 31500 nat 102 ip from any to any via $pif1 // $pif1 nat
  $cmd add       skipto 35000 tag 102 ip from any to any in recv $pif1
fi

if [ $pif2status == "UP" ]; then
  $cmd add 32500 nat 120 ip from any to any via $pif2 // $pif2 nat 
  $cmd add       skipto 35000 tag 120 ip from any to any in recv $pif2
fi


################################################################################

$cmd add 35000 allow tcp from any to any established // Allow TCP through if setup succeeded

$cmd add 50000 allow all from any to any
$cmd add 65534 deny all from any to any

################################################################################

exit 0

MPD5 as PPPoE client

Default route will be set using up-script_fib_0.sh. This is workaround to avoid identical gateways in case of using two lines from single ISP. Use different fib's for each ISP.

/usr/local/etc/mpd5/mpd.conf:

startup:
# Name password password_user
  set user myuser mypass admin
# console on localhost
  set console self 127.0.0.1 5005
  set console open
  set web self 0.0.0.0 5006
  set web open

# default settings
default:
  load pppoe_client_101
  load pppoe_client_102

pppoe_client_101:
  create bundle static B1
  set iface name adsl1
  set iface enable tcpmssfix 
  set iface up-script /usr/local/etc/mpd5/up-script_fib_0.sh
  set iface down-script /usr/local/etc/mpd5/down-script_fib_0.sh
# Default route is added via up-script
#  set iface route default
  set ipcp ranges 0.0.0.0/0 0.0.0.0/0
  create link static L1 pppoe
  set link action bundle B1
  set auth authname PPPOE_USERNAME
  set auth password PPPOE_PASSWORD
  set link max-redial 0
  set link mtu 1492
  set link mru 1492
  set link keep-alive 10 60
# interface to PPPoE
  set pppoe iface vlan101
#  set pppoe iface pif0 
  set pppoe service ""
# start connection
  open 

pppoe_client_102:
  create bundle static B2
  set iface name adsl2
  set iface enable tcpmssfix 
  set iface up-script /usr/local/etc/mpd5/up-script_fib_1.sh
  set iface down-script /usr/local/etc/mpd5/down-script_fib_1.sh
# Default route is added via up-script
#  set iface route default
  set ipcp ranges 0.0.0.0/0 0.0.0.0/0
  create link static L2 pppoe
  set link action bundle B2
  set auth authname PPPOE_USERNAME
  set auth password PPPOE_PASSWORD
  set link max-redial 0
  set link mtu 1492
  set link mru 1492
  set link keep-alive 10 60
# interface to PPPoE
  set pppoe iface vlan102
#  set pppoe iface pif0
  set pppoe service ""
# start connection
  open

/usr/local/etc/mpd5/up-script_fib_0.sh:

#!/bin/sh

echo "`date` UP   $@" >> /tmp/firewall.sh.log

# Manually adding default route to avoid error with identical destination gateways 
EXT_IF_IP=$4
setfib 0 route add default -interface $1 

/etc/firewall &

exit 0

/usr/local/etc/mpd5/down-script_fib_0.sh:

#!/bin/sh

echo "`date` DOWN $@" >> /tmp/firewall.sh.log

# Manually adding default route to avoid error with identical destination gateways
setfib 0 route del default -interface $1 

/etc/firewall &

exit 0

setfib + dhclient

/etc/rc.conf:

# setfib 2 dhclient vlan200 
vlan200_enable="YES"

/usr/local/etc/rc.d/vlan200:

#!/bin/sh

# PROVIDE: sumtel-watchdog
# REQUIRE: DAEMON
# KEYWORD: shutdown
#
# Add the following lines to /etc/rc.conf.local or /etc/rc.conf to
# enable vlan200:
#
# vlan200_enable (bool): Set to NO by default.  Set it to YES to
#         enable vlan200.
#

. /etc/rc.subr

name="vlan200"
rcvar="vlan200_enable"

pidfile="/var/run/${name}.pid"

start_cmd=${name}_start
stop_cmd=${name}_stop

vlan200_start() {
  /usr/sbin/setfib 2 /sbin/dhclient vlan200
}

vlan200_stop() {
  /bin/pgrep -f "dhclient: vlan200" | /usr/bin/xargs kill
}



load_rc_config $name

: ${vlan200_enable="NO"}

run_rc_command "$1"

watchdog script

Following script checks internet connectivity and reloads IPFW rules if status has changed.

/etc/rc.conf:

sumtelwatchdog_enable="YES"

/usr/local/etc/rc.d/sumtelwatchdog:

#!/bin/sh

# PROVIDE: sumtel-watchdog
# REQUIRE: DAEMON
# KEYWORD: shutdown
#
# Add the following lines to /etc/rc.conf.local or /etc/rc.conf to
# enable sumtelwatchdog:
#
# sumtelwatchdog_enable (bool): Set to NO by default.  Set it to YES to
#         enable sumtelwatchdog.
#

. /etc/rc.subr

name="sumtelwatchdog"
rcvar="sumtelwatchdog_enable"

pidfile="/var/run/${name}.pid"

start_cmd=${name}_start
stop_cmd=${name}_stop

sumtelwatchdog_start() {
  /usr/sbin/daemon -f -p /var/run/${name}.pid /root/${name}.sh
}

sumtelwatchdog_stop() {
  kill `cat /var/run/${name}.pid`
  rm -f /var/run/${name}.pid
}



load_rc_config $name

: ${sumtelwatchdog_enable="NO"}

run_rc_command "$1"

/root/sumtelwatchdog.sh:

#!/bin/sh

# Variables
HOST1="8.8.8.8"
HOST2="172.29.61.11"
ADDRESS="ya.ru"
FIB="2"
FILE="/vlan200.status"

# Infinite loop
# If all three checks will fail then status will be "DOWN"
while :
do 
  setfib ${FIB} dig @${HOST1} ${ADDRESS} 1>/dev/null 2>/dev/null 
  STATUS1=`echo $?`
  sleep 20

  setfib ${FIB} dig @${HOST2} ${ADDRESS} 1>/dev/null 2>/dev/null
  STATUS2=`echo $?`
  sleep 20

  if [ ${STATUS1} -ne 0 ] && [ ${STATUS2} -ne 0 ]; 
    then 
      STATUS=`cat ${FILE}`
      if [ ${STATUS} != "DOWN" ]; then
        echo "DOWN" > ${FILE}
        /etc/firewall
      fi
    else
      STATUS=`cat ${FILE}`
      if [ ${STATUS} != "UP" ]; then
        echo "UP" > ${FILE}
        /etc/firewall
      fi
  fi
done

exit 0

arpalert

Purpose of this following configuration is to add LAN IP's to IPFW tables.

/usr/local/etc/rc.d/arpalert:

#!/bin/sh

# PROVIDE: arpalert
# REQUIRE: DAEMON
# KEYWORD: shutdown
#
# Add the following lines to /etc/rc.conf.local or /etc/rc.conf to
# enable arpalert:
#
# arpalert_enable (bool): Set to NO by default.  Set it to YES to
#         enable arpalert.
#

. /etc/rc.subr

name="arpalert"
rcvar=arpalert_enable

command="/usr/local/sbin/${name}"
required_files="/usr/local/etc/arpalert/${name}.conf"

load_rc_config $name

: ${arpalert_enable="NO"}

run_rc_command "$1"

/usr/local/etc/arpalert/arpalert.conf (only changed values):

user = root
interface = lan0
action on detect = "/usr/local/etc/arpalert/script.pl"
mac timeout = 1200

/usr/local/etc/arpalert/script.pl:

#!/usr/bin/perl

use strict;
use warnings;

#Check if copy of process is already running:
my $pids=`pgrep -f "/usr/bin/perl /usr/local/etc/arpalert/script.pl" | wc -l`;
if ( $pids > 1 ) {
  print "Another copy is already running.\n";
  exit 1;
} 

# Variables and initial data
my $interface="lan0";
my $prob;
my %arp_hash; 
my %tables;
my @arp_out=`/usr/sbin/arp -a -i $interface`;

# Writing timestamp
`date >> /tmp/table_balance.log`;

# Output to file 
open (LOGFILE, '>> /tmp/table_balance.log');

# Storing IP from 'arp' command in %arp_hash
foreach (@arp_out) {
  $_ =~ m|\((\S+?)\)|;  # Match string
  $arp_hash{$1}='';
}

foreach my $table (101, 102, 120) {

  # Storing IP from 'ipfw table' command in %tables
  foreach (`/sbin/ipfw table $table list`) {
    $_ =~ m|^(\S+?)\/|;
    $tables{"$table"}->{"$1"} = '1';
  }

  # Checking existance of IP in %arp_hash
  foreach my $ip (keys %{$tables{$table}}) {
    if (exists $arp_hash{$ip}) {
      $arp_hash{$ip} = "$table";
    } else {
      print LOGFILE "Removing IP:$ip from table $table\n";
      print `/sbin/ipfw table $table delete $ip`;
      delete $tables{$table}->{$ip};
    }
  }
}

# Adding new IP addreses to tables 
foreach my $ip (keys %arp_hash) {
  if ($arp_hash{$ip} eq '') {
    $prob = rand(100); 
    if ( $prob > 66 ) {
      print LOGFILE "Adding IP:$ip to the table 101. prob=$prob\n";
      print `/sbin/ipfw table 101 add $ip`;
    } elsif ( $prob < 33 ) {
      print LOGFILE "Adding IP:$ip to the table 102. prob=$prob\n";
      print `/sbin/ipfw table 102 add $ip`;
    } else {
      print LOGFILE "Adding IP:$ip to the table 120. prob=$prob\n";
      print `/sbin/ipfw table 120 add $ip`;
    }
  } 
} 

# Debug info
#foreach my $ip (keys %arp_hash) {
#  print "key = '$ip'  value='$arp_hash{$ip}' \n" if ($arp_hash{$ip} ne ''); 
#} 
print "Done.\n";

# Closing file
close (LOGFILE); 

exit 0