PfSense blocks traffic coming from SubnetA to SubnetB

viragomann

@yquirion
So the packets from B go out on A WAN, but are not natted.

So presumably there is something wrong with the outbound NAT. Can you show it, please?

yquirion

Hi @viragomann,

Here is almost all of it:

I'm using some VLANs as well as a VPN connection, but do not bother with those.

Thanks
Yanick

viragomann

@yquirion
Yeah, you're missing the rule for the B LAN.
Maybe you've chosen the wrong interface by mistake.

yquirion

Hi @viragomann,

You're right. I change that to see what it will do, but it was WAN before. I will put it back, but unfortunately it won't solve the issue...

Here it is:

ping 8.8.8.8

Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Thanks
Yanick

viragomann

@yquirion
Should work, since the packets are directed out on WAN.

As suggested before, reboot the box. Or at least flush the states.

yquirion

Hi @viragomann,

I just rebooted and it doesn't solve the issue.

I really don't understand this one!

Thank you so much for your help!

Regards,
Yanick

viragomann

@yquirion
Search the state table on A for the source IP.

Use packet capture to see, what's going on there.

yquirion

Hi @viragomann,

Here are some tests I've done.

From SiteB, when I ping anything on the Internet, let's take one more time Google DNS 8.8.8.8, I will have this result for command tcpdump -nni igb2 icmp and host 8.8.8.8 I execute on my PFSense. Interface igb2 is the physical interface used by SITEB in pfsense:

22:27:29.720748 IP 192.168.88.10 > 8.8.8.8: ICMP echo request, id 7, seq 48849, length 40
22:27:34.632365 IP 192.168.88.10 > 8.8.8.8: ICMP echo request, id 7, seq 48850, length 40
22:27:39.639399 IP 192.168.88.10 > 8.8.8.8: ICMP echo request, id 7, seq 48851, length 40
22:27:44.644884 IP 192.168.88.10 > 8.8.8.8: ICMP echo request, id 7, seq 48852, length 40

In the meantime, running tcpdump on WAN interface igb0, will not produce any output:

tcpdump -nni igb0 icmp and host 8.8.8.8
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on igb0, link-type EN10MB (Ethernet), snapshot length 262144 bytes

So it means the traffic from SiteB never redirected to the SiteA WAN's interface.

When doing that ping test from the SiteB's Mikrotik Router, the tcpdump running on interface igb2 on the pfsense router will show this:

22:33:36.921387 IP 10.0.0.4 > 8.8.8.8: ICMP echo request, id 1711, seq 0, length 36
22:33:37.924867 IP 10.0.0.4 > 8.8.8.8: ICMP echo request, id 1711, seq 1, length 36
22:33:38.928295 IP 10.0.0.4 > 8.8.8.8: ICMP echo request, id 1711, seq 2, length 36
22:33:39.931764 IP 10.0.0.4 > 8.8.8.8: ICMP echo request, id 1711, seq 3, length 36
22:33:40.934412 IP 10.0.0.4 > 8.8.8.8: ICMP echo request, id 1711, seq 4, length 36

10.0.0.0/29 IPs from the router are normal because the P2P link between the two site is using this subnet.

When I ping 8.8.8.8 from SiteA computer (192.168.2.35), I will see that on the states page:

But when doing this from SiteB, I don't see any "icmp" traffic going through.

Correction: After looking again, I can see the state of ICMP from SiteB:

But still "Request timed out".

Will continue investigating!

Thanks again for your help!

Yanick

viragomann

@yquirion said in PfSense blocks traffic coming from SubnetA to SubnetB:

In the meantime, running tcpdump on WAN interface igb0, will not produce any output:

Did you change the firewall rules?
What rules to you have at A on SITEB interface?

@yquirion said in PfSense blocks traffic coming from SubnetA to SubnetB:

When I ping 8.8.8.8 from SiteA computer (192.168.2.35), I will see that on the states page:

Don't filter the interface, only the destination IP.
If the ping works I'd expect to see two states for this. One on the incoming interface (e.g. VLAN2) and one on the outgoing (WAN).

I assume, if you try to access the internet from B the WAN state is missing.

yquirion

Hi @viragomann,

I've made an error. Here are the new result from a fresh test

From SiteA - Interface VLAN2

From SiteB - Interface SITEB

So we can see that nothing from Interface SITEB in going to the WAN Interface.

Here are the rules on the WAN interface:

And the rules on the SITEB Interface:

Here are the interface configuration:

All those 3 interfaces are physical interfaces on my PfSense router.

Outbound rules:

I really don't understand why nothing is going to the WAN interface from SITEB interface.

Thanks again!

Yanick

yquirion

Hi @viragomann,

I found something.

Just after sending the reply, I did change this:

Those two options were selected on the WAN interface.

After that I see I could ping 8.8.8.8, but nothing else... Then if I stop the ping to 8.8.8.8, it won't restarts until I play again with those parameter (re-enable them).

I reset all states; no luck, I rebooted the pfsense, same thing...

At this moment I have a running ping from SITEB to 8.8.8.8. It works. I see the corresponding traffic on the igb0 (WAN) interface using tcpdump.

Now, if I stop that ping, then wait for the states being cleared, then restart it, it is no longer working.

Maybe I am running into a bug with pfsense, but all of this has no sense at all.

Thanks
Yanick

viragomann

@yquirion
WTF! Just noticed, that you have "static port" checked in the outbound NAT rule.
It wasn't checked before!

Why did you change things, you're not advised to change? You needed just to edit the rule and change the interface to WAN.
This makes it hard to help you with your issues.

Those two options were selected on the WAN interface.

At A WAN this setting should be checked. At B not, mentioned in my very first post.
At A VLAN2 it has to be unchecked. But this might have been the case before, otherwise you were not able to access A from B at all.

yquirion

Hi @viragomann,

That is very odd. I never notice it. Sorry about that. However, I just look at it and since that post, it has been corrected.

Regarding the 2 options, I don't have those on siteB because siteB is using a Mikrotik router. From the pfsense router on sitea, those options are disabled on all interface (was only enable on the WAN before).

I'm not home for the weekend so I cannot make any other test on this.. But that os very strange that, while pfsense is applying the change of the Block private networks and loopback addresses, for a second the ping will work until I cancel it and the connection is being cleared of the state table...

Thanks again, and I'm really sorry having made that mistake. I'm just testing stuff between replies!

Yanick

yquirion

Hi @viragomann,

I found it!

It was because of a miss configuration into my client OpenVPN connection.

Here is a post that explain what was my problem:

https://www.reddit.com/r/PFSENSE/comments/i125ig/default_route_now_set_to_vpn_client_instead_of/

I was looking into this because of this:

# route get 1.1.1.1
   route to: one.one.one.one
destination: default
       mask: 128.0.0.0
    gateway: 10.4.112.1
        fib: 0
  interface: ovpnc1
      flags: <UP,GATEWAY,DONE,STATIC>
 recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
       0         0         0         0      1500         1         0

That gateway of 10.4.112.1 was the gateway of my OpenVPN client connection. When I stop the service for that VPN connection, that was the result of the same command:

/root: route get 8.8.8.8
   route to: dns.google
destination: default
       mask: default
    gateway: modemcable001.40-53-24.mc.videotron.ca
        fib: 0
  interface: igb0
      flags: <UP,GATEWAY,DONE,STATIC>
 recvpipe  sendpipe  ssthresh  rtt,msec    mtu        weight    expire
       0         0         0         0      1500         1         0

So I made search on why the OpenVPN client was adding that route to the routing table:

0.0.0.0/1	<<VPN Interface Gateway IP>>

And I found the post tjhat somve my issue.

I would like to thank you very much as well as @skenigma for your time helping me solving the issue.

Best Regards,
Yanick