Load-balancing PPTP connections

Question

I'm trying to load balance two PPTP connections, connected to the same server. I use the following script, but there is no send and receive via PPTP connections. What part am I doing wrong? Are there better ways to acomplish this? I used also nexthop mode of ip route command but the problem is that multiple connections to the same IP are routed throught the same interface.

#!/bin/bash

VPNSERVER=x.x.x.x

# Enable IP forwarding
sysctl -w net.ipv4.ip_forward=1
echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter

# Create a new table for physical interface
physip=$(ip addr show eth0 | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)
echo "Physical interface's IP: $physip"
ip route flush table 10
ip route add default via $physip dev eth0 table 10
ip rule add from $physip table 10
ip rule add fwmark 10 table 10

# Replace default gateway
ip route replace default via 127.0.0.1

# Do not mark packets going to pptp server
iptables -A OUTPUT -d $VPNSERVER -p gre -j ACCEPT
iptables -A OUTPUT -d $VPNSERVER -p tcp --dport 1723 -j ACCEPT

iptables -t mangle -A PREROUTING -j CONNMARK --restore-mark
iptables -t mangle -A PREROUTING -m mark ! --mark 0 -j ACCEPT

pppd unit 101 noauth refuse-eap refuse-pap refuse-chap \
    refuse-mschap require-mschap-v2 name "user01" remotename \
    vpnserver file /etc/ppp/options.pptp maxfail 1 updetach \
    pty "pptp $VPNSERVER --localbind $physip --nolaunchpppd" &> /dev/null

pppd unit 102 noauth refuse-eap refuse-pap refuse-chap \
    refuse-mschap require-mschap-v2 name "user01" remotename \
    vpnserver file /etc/ppp/options.pptp maxfail 1 updetach \
    pty "pptp $VPNSERVER --localbind $physip --nolaunchpppd" &> /dev/null

# Get interface IP addresses
ifip1=$(ip addr show ppp101 | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)
ifip2=$(ip addr show ppp102 | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)

# Create a unique routing table for each connection
ip route flush table 101
ip route add default dev ppp101 table 101
ip rule add from $ifip1 table 101
ip rule add fwmark 101 table 101

# Create a unique routing table for each connection
ip route flush table 102
ip route add default dev ppp102 table 102
ip rule add from $ifip2 table 102
ip rule add fwmark 102 table 102

# Load balance connections
iptables -t mangle -A OUTPUT -m state --state NEW -m statistic --mode nth --every 2 --packet 0 -j MARK --set-mark 101
iptables -t mangle -A OUTPUT -m state --state NEW -m statistic --mode nth --every 2 --packet 1 -j MARK --set-mark 102

iptables -t nat -A POSTROUTING -m mark --mark 101 -j SNAT --to-source $ifip1
iptables -t nat -A POSTROUTING -m mark --mark 102 -j SNAT --to-source $ifip2

iptables -t mangle -A POSTROUTING -j CONNMARK --save-mark

Just out of curiosity, why would you load balance two pptp connections to the same pptp server? — ErikE, Jan 31 '14 at 20:18
@ErikE: The download rate is throttled on per connection basis, and each user is allowed to connect with at most two devices at the same time. I'm just trying to get twice the bandwidth on the same device. — Ali Alidoust, Jan 31 '14 at 22:53

score 0 · Accepted Answer · answered Nov 18 '16 at 11:04

Here is the final solution I used:

server=x.x.x.x
physip=$(ip addr show $dev | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)

pppd unit 101 noauth refuse-eap refuse-pap refuse-chap \
        refuse-mschap require-mschap-v2 name user01 remotename \
        vpnserver file /etc/ppp/options.pptp persist maxfail 1 updetach \
        pty "pptp $server --localbind $physip --nolaunchpppd" &> /dev/null

pppd unit 102 noauth refuse-eap refuse-pap refuse-chap \
        refuse-mschap require-mschap-v2 name user01 remotename \
        vpnserver file /etc/ppp/options.pptp persist maxfail 1 updetach \
        pty "pptp $server --localbind $physip --nolaunchpppd" &> /dev/null

ifip1=$(ip addr show ppp101 | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)
ifip2=$(ip addr show ppp102 | grep inet | grep -v inet6 | cut -d' ' -f6 | cut -d'/' -f1)

iptables -t nat -A POSTROUTING -o ppp101 -j SNAT --to-source $ifip1
iptables -t nat -A POSTROUTING -o ppp102 -j SNAT --to-source $ifip2

ip route flush cache
ip route replace default scope global nexthop dev ppp101 weight 1 nexthop dev ppp102 weight 1

Load-balancing PPTP connections

1 Answers1