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So I know there is another question on here that I used as a guide as it was super helpful! (Setup routing and iptables for new VPN connection to redirect **only** ports 80 and 443) Only my goal is a bit different. I am running a headless gui-less install of Ubuntu Server 12.04 that is being used for a variety of different purposes... I would like all traffic to travel un-prohibited through my ISP except for my transmission traffic. I have a VPN i subscribe to that allows me access for which I only want to direct a single port's traffic to. I am currently using a modified version of the code from the above link. My current code is below:
#!/bin/sh
sleep 200
DEV1=eth0
IP1=`ifconfig|perl -nE'/dr:(\S+)/&&say$1'|grep 192.`
GW1=10.0.1.1
TABLE1=open
TABLE2=vpn
DEV2=tun0
IP2=`ifconfig|perl -nE'/dr:(\S+)/&&say$1'|grep 10.`
GW2=`route -n | grep 'UG[ \t]' | awk '{print $2}'`
ip route flush table $TABLE1
ip route flush table $TABLE2
ip route show table main | grep -Ev ^default | while read ROUTE ; do
ip route add table $TABLE1 $ROUTE
ip route add table $TABLE2 $ROUTE
done
ip route add table $TABLE1 $GW1 dev $DEV1 src $IP1
ip route add table $TABLE2 $GW2 dev $DEV2 src $IP2
ip route add table $TABLE1 default via $GW1
ip route add table $TABLE2 default via $GW2
echo "1" > /proc/sys/net/ipv4/ip_forward
echo "1" > /proc/sys/net/ipv4/ip_dynaddr
echo "2" > /proc/sys/net/ipv4/conf/tun0/rp_filter
ip rule add from $IP1 lookup $TABLE1
ip rule add from $IP2 lookup $TABLE2
ip rule add fwmark 1 lookup $TABLE1
ip rule add fwmark 2 lookup $TABLE2
iptables -t nat -A POSTROUTING -o $DEV1 -j SNAT --to-source $IP1
iptables -t nat -A POSTROUTING -o $DEV2 -j SNAT --to-source $IP2
iptables -t nat -A PREROUTING -m state --state ESTABLISHED,RELATED -j CONNMARK --restore-mark
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j CONNMARK --restore-mark
iptables -t nat -A PREROUTING -i $DEV1 -m state --state NEW -j CONNMARK --set-mark 1
iptables -t nat -A PREROUTING -i $DEV2 -m state --state NEW -j CONNMARK --set-mark 2
iptables -t nat -A PREROUTING -m connmark --mark 1 -j MARK --set-mark 1
iptables -t nat -A PREROUTING -m connmark --mark 2 -j MARK --set-mark 2
iptables -t nat -A PREROUTING -m state --state NEW -m connmark ! --mark 0 -j CONNMARK --save-mark
iptables -t mangle -A PREROUTING -i $DEV2 -m state --state NEW -p tcp --dport 44447 -j CONNMARK --set-mark 2
iptables -t mangle -A PREROUTING -i $DEV2 -m state --state NEW -p udp --dport 44447 -j CONNMARK --set-mark 2
route del default
ip route del 0.0.0.0/1
ip route del 128.0.0.0/1
route add default gw $GW1 eth0
I took into account the original poster's own comments, modified it to my IP configuration and port needs... extended the sleep to ensure the OpenVPN configuration had occured... And then also deleted two routes that I believe were added by my VPN provider for a fallback incase the default route failed... Now everything seems to be okay except a few things...
- traceroutes fail... completely...
$ traceroute yahoo.com traceroute to yahoo.com (206.190.36.45), 30 hops max, 60 byte packets 1 * * * 2 * * * 3 * * * 4 * * * 5 * * *
- ping results in 100% packet loss
$ ping google.com PING google.com (173.194.43.46) 56(84) bytes of data. ^C --- google.com ping statistics --- 119 packets transmitted, 0 received, 100% packet loss, time 118945ms
I don't know what is causing this???
$ nslookup > google.com Server: 10.0.1.1 Address: 10.0.1.1#53 Non-authoritative answer: Name: google.com Address: 173.194.43.46 Name: google.com Address: 173.194.43.38 Name: google.com Address: 173.194.43.35 Name: google.com Address: 173.194.43.41 Name: google.com Address: 173.194.43.39 Name: google.com Address: 173.194.43.34 Name: google.com Address: 173.194.43.36 Name: google.com Address: 173.194.43.37 Name: google.com Address: 173.194.43.32 Name: google.com Address: 173.194.43.40 Name: google.com Address: 173.194.43.33
route table below:
$ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default Rolands-AirPort 0.0.0.0 UG 0 0 0 eth0 default Rolands-AirPort 0.0.0.0 UG 100 0 0 eth0 10.0.1.0 * 255.255.255.255 UH 0 0 0 eth0 10.0.1.0 * 255.255.255.0 U 0 0 0 eth0 10.4.0.1 10.4.49.21 255.255.255.255 UGH 0 0 0 tun0 10.4.49.21 * 255.255.255.255 UH 0 0 0 tun0 hosted-by.lease Rolands-AirPort 255.255.255.255 UGH 0 0 0 eth0
Any help would be greatly appreciated!
I looked further into my route tables and I found that for some reason the VPN was also pushing a route into my "open" table to override my defaults to my ISP. I am adding these two lines to my script to successfully resolve the issue.
ip route del table open 0.0.0.0/1
ip route del table open 128.0.0.0/1
– user230409 – 2013-06-12T19:10:00.467well my routing is still not working right... I now have successful pings and traceroutes to external ip's so I know my traffic is defaulting to the open table or using the main table... However my transmission client does not seem to be using the VPN and as such I am not connectable. I can see that transmission is announcing my external IP from my ISP and not the IP from my VPN. I am attempting to overcome this by adding
ip route add table vpn default dev tun0
because there was no default route in my VPN table... if anyone has any ideas please help! – user230409 – 2013-06-12T21:29:14.517