offloading OpenVPN using external gateway

chrispazz

Currently I am using my pfsense for firewalling and routing specific traffic (based on firewall rules) to OpenVPN client configured within pfsense.

I would like to offload pfsense from the openvpn computing effort and I set up an external raspberry PI that acts as VPN Gateway (eth0 forward to tun0 created by openvpn client).

I cannot configure pfsense to use that gateway for specific rules.

pfsense is 192.168.99.1 (fixed) and external gateway is 192.168.5.99 (get static IP from internet router that is 192.168.5.254).
the gateway is reachable from pfsense.
I added it in pfsense as a gateway and created a rule to set all traffic from a client outside using 192.168.5.99 as gateway.

Using this rule make all traffic going out in internet without using the VPN connection!

If I try a traceroute from the Raspberry gateway to external address, it correctly goes thru VPN.....

Any help?

bingo600

@chrispazz

Not the greatest explanation..
A drawing would help

Could it be the portforward still points to the pfSense , and not the RasPI ?

chrispazz

@bingo600 currently I am using portforward only to manage incoming external connections...
Why do you think it is involved in outgoing connections?

Ty

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600 currently I am using portforward only to manage incoming external connections...
Why do you think it is involved in outgoing connections?

Ty

I was not sure it was outbound.

chrispazz

@bingo600 here it is a little drawing.... :)

I know, I have to buy an hardware pfsense....

bingo600

@chrispazz

Your pfSense is the main router , and has to make the decision, what "traffic" to forward to the RasPI , you have to "set that up" in the pfSense (routing or policy routing).

What is nets are "behind" the OpenVPN ?

chrispazz

@bingo600 Currently I am using a "per IP" policy so only specific clients and specific traffic is going thru VPN.
I am using only firewall rules by indicating specific outgoing gateway (WAN or VPN).

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600 Currently I am using a "per IP" policy so only specific clients and specific traffic is going thru VPN.
I am using only firewall rules by indicating specific outgoing gateway (WAN or VPN).

Then i suppose you have to make policy routing.

Make an IP host alias Ie. OVPN_FORWARDS , and put your IP's in that one.

Then make a policy route rule , AF IPv4 , Proto any , matching Source IP = OVPN_FORWARDS , dest any.

Click advanced options

Set the Raspi Gateway as Gateway

Pray that you have enabled forwarding in Raspbian Linux

Remember that pfSense matches on inbound traffic , meaning the rule has to be applied on all interfaces where matching ip's could "enter" (Ingress traffic).

/Bingo

chrispazz

@bingo600 here we are! this is exactly what I did before writing here! ahahahah
Yes I enabled forwarding in Raspbian but I cannot understand why it is going outside without using VPN

I am sure it is using the new rule because of some tests I did....

I am starting to suppose that the problem could be on the RPI side....strange since it is working from SSH....

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

Yes I enabled forwarding in Raspbian but I cannot understand why it is going outside without using VPN

Does the package reach the RasPI (using the gateway you set) ?
Or does the pfSense never send it to the Raspi ?

chrispazz

@bingo600 I do not know how to check this on the RPI side....

I followed this guide:

https://www.instructables.com/Raspberry-Pi-VPN-Gateway/

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600 I do not know how to check this on the RPI side....

Quick hack
Enable temporary logging on the Policy Rule , look for log entries to confirm your rule matches "interesting traffic".

Real Packet capture (on pfSense).
Diagnostic --> Packet Capture

I suppose your pfSense Wan Interface is the one connecting to the "ISP Router LAN" ?

Packet Capture on pfSense
If you have a screen + kbd on the RasPi , you could install wireshark on that one , to do the packet capture.

If only SSH , install tcpdump on the RasPI

How about NAT ?
Are you natting on your pfSense WAN IF ?

/Bingo

bingo600

You say your pfSense is 192.168.99.1 , but the drawing shows 99.250

Is the 99.1 interface a pfSense "inside Lan" ip ?

How does the 192.168.99.x interface relate on the drawing ?

I expect your pfSense to have a WAN ip on the ISP router LAN , meaning the 192.168.5.x range.

Since you say you can ping and prob SSH to the Raspi , i assume that is correct or ??

chrispazz

@bingo600 NAS is 99.250.
Inside NAS (Synology) I run a VM with pfsense (99.1).

I tried enabling logging on the rule and I can confirm it is using it.
Yes, my pfsense WAN interface is the one connecting to the ISP router.
And yes, I am using NAT on the pfsense WAN if....

bingo600

@chrispazz

Just for completeness
What is your pfSense WAN IP ?

chrispazz

@bingo600 it is 192.168.5.254

bingo600

@chrispazz

??

Then what is your ISP router inside ip ?

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

I tried enabling logging on the rule and I can confirm it is using it.

Ok

Now try to do a packet trace on the pfSense WAN

Set host address to the Raspi IP

And generate some traffic destined for VPN

chrispazz

@bingo600 oops....sorry. Inside IP of router is 192.168.5.254.

Pf sense has 192.168.5.1 on the WAN side...

chrispazz

@bingo600

Activated packet capture on host 192.168.5.9 and opened a webpage with www.google.it:

16:58:57.410983 IP 192.168.5.1 > 192.168.5.9: ICMP echo request, id 43267, seq 8815, length 9
16:58:57.920985 IP 192.168.5.1 > 192.168.5.9: ICMP echo request, id 43267, seq 8816, length 9

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600

Activated packet capture on host 192.168.5.9 and opened a webpage with www.google.it:

16:58:57.410983 IP 192.168.5.1 > 192.168.5.9: ICMP echo request, id 43267, seq 8815, length 9
16:58:57.920985 IP 192.168.5.1 > 192.168.5.9: ICMP echo request, id 43267, seq 8816, length 9

Where did 192.168.5.9 come from ??
did you mean 5.99

chrispazz

@bingo600 yes is 5.99 :) don't hate me eheheh

bingo600

@chrispazz

So we have confirmed that the ICMP (ping) packages are actually being "policy routed" from 5.1 (pfSense) to 5.99 (RasPI)

We don't see any Echo reply ... The issue is probably on the RasPI

bingo600

On the Raspi (as root)

What does a : sudo iptables -L show ?

And this one ?

chrispazz

This post is deleted!

bingo600

Did you reboot the RasPI after enabling forwarding ?

chrispazz

@bingo600 yes, forward is activated.

Chain INPUT (policy DROP)
target prot opt source destination
ACCEPT all -- anywhere anywhere
ACCEPT icmp -- anywhere anywhere
ACCEPT tcp -- anywhere anywhere tcp dpt:ssh
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED

Chain FORWARD (policy DROP)
target prot opt source destination
ACCEPT all -- anywhere anywhere
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

and yes, I rebooted it a lot of times :)

bingo600

@chrispazz

Does this one give the expected result , should be your (OpenVPN public ip) ?

wget http://ipinfo.io/ip -qO -

Can you ping the google.it from the RasPI ?

/Bingo

chrispazz

@bingo600 said in offloading OpenVPN using external gateway:

wget http://ipinfo.io/ip -qO -

Both yes.
And if I test a traceroute from raspi I can confirm it is going outside using VPN connection....

bingo600

@chrispazz

Now : I would connect a PC directly to the RasPI , or directly to the ISP inside LAN , and set def-gw to the RasPI , and maybe DNS to 8.8.8.8

Then start debugging directly between the PC & The Raspi.

This can come in handy ... Disables all iptables stuff on the Raspi.
But only for this "boot sesion"

iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -t mangle -F
iptables -t mangle -X
iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT

I use these rules on my Deb10 machines , for OVPN to a VPN provider.

Remember to replace ens192 with the name of your ethernet interface on the Raspi.

# Default policy to drop all incoming packets
iptables -P INPUT DROP
iptables -P FORWARD DROP

# Accept incoming packets from localhost and the LAN interface
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -i ens192 -j ACCEPT

# Accept incoming packets from the WAN if the router initiated
# the connection
iptables -A INPUT -i tun0 -m conntrack \
    --ctstate ESTABLISHED,RELATED -j ACCEPT

# Forward LAN packets to the WAN
iptables -A FORWARD -i ens192 -o tun0 -j ACCEPT

# Forward WAN packets to the LAN if the LAN initiated the
# connection
iptables -A FORWARD -i tun0 -o ens192 -m conntrack \
    --ctstate ESTABLISHED,RELATED -j ACCEPT

# NAT traffic going out the WAN interface
iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE
#

Remember to save new rules if you change them

sudo systemctl enable netfilter-persistent

chrispazz

@bingo600 said in offloading OpenVPN using external gateway:

sudo systemctl enable netfilter-persistent

I made some other tests.

Raspberry is working good if I set a client to use it as network interface gateway and connection will go thru VPN (using my own iptables rules or yours).

So it seems that when I go thru pfsense, WAN main gateway (ISP router) is getting used instead of firewall rule gateway...

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600 said in offloading OpenVPN using external gateway:

sudo systemctl enable netfilter-persistent

I made some other tests.

Raspberry is working good if I set a client to use it as network interface gateway and connection will go thru VPN (using my own iptables rules or yours).

So it seems that when I go thru pfsense, WAN main gateway (ISP router) is getting used instead of firewall rule gateway...

That doesn't make sense
The packet trace you made doesn't lie.

bingo600

Now is the time to use tcpdump on the RasPI

https://kalitut.com/record-network-traffic-with-raspberry/

To see what it actually receives & forwards

chrispazz

@bingo600
This is traceroute from the client with the firewall rule applies:

traceroute to www.google.it (216.58.215.227), 64 hops max, 52 byte packets
1 192.168.5.254 (192.168.5.254) 2.370 ms 1.583 ms 1.516 ms

The first hop go to ISP gateway....I can't see Raspi here...

bingo600

@chrispazz
But that is not consistent with the packet trace you made on the pfSense

Can you do another trace , and then the traceroute ?

chrispazz

@bingo600 if I try a trace to www.google.it IP address as host I get this:

18:25:31.846958 IP 192.168.5.1.4704 > 172.217.168.35.443: UDP, length 1350
18:25:31.883433 IP 172.217.168.35.443 > 192.168.5.1.4704: UDP, length 1350

so it is using 192.168.5.1 as gateway....

chrispazz

@chrispazz Perhaps I understand the problem.

My WAN interface is getting IP from ISP router (DHCP server on 192.168.5.0).
The ISP gateway is getting on top of the firewall rule gateway....

This is WAN if on pfsense:

em1.90: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1492
options=3<RXCSUM,TXCSUM>
ether 02:11:32:25:4e:f9
inet6 fe80::11:32ff:fe25:4ef9%em1.90 prefixlen 64 scopeid 0x8
inet 192.168.5.1 netmask 0xffffff00 broadcast 192.168.5.255
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
vlan: 90 vlanpcp: 0 parent interface: em1
groups: vlan

chrispazz

No wrong.

192.168.5.1 is pfsense.... :(

bingo600

@chrispazz said in offloading OpenVPN using external gateway:

@bingo600 if I try a trace to www.google.it IP address as host I get this:

18:25:31.846958 IP 192.168.5.1.4704 > 172.217.168.35.443: UDP, length 1350
18:25:31.883433 IP 172.217.168.35.443 > 192.168.5.1.4704: UDP, length 1350

so it is using 192.168.5.1 as gateway....

Nope
It's using 5.1 as source IP (Consistent with your WAN NAT)

If you enable logging on the Policy rule , do you see any log lines ?

Now you are not doing the traceroute on the pfSense box ... Are you ?

What PC ip address are you doing the traceroute from , and are you 100% sure you have that ip in the OPENVPN Alias , and a policy route rule on the pfSense interface that that PC is connected to ?

chrispazz

@bingo600 said in offloading OpenVPN using external gateway:

If you enable logging on the Policy rule , do you see any log lines ?

Yes, it is the only rules that has logging

Now you are not doing the traceroute on the pfSense box ... Are you ?

No, I am doing it from iMac client (192.168.20.110)

What PC ip address are you doing the traceroute from , and are you 100% sure you have that ip in the OPENVPN Alias , and a policy route rule on the pfSense interface that that PC is connected to ?

I am using a firewall rule like this on the same interface of the client (192.168.20):

and NVPNGTW is the gateway I added to pfsense in the gateway section.

offloading OpenVPN using external gateway

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