topic Re: Problem that is bridge Mode between Aruba Switch and Fortigate in Firewall and Security Management

Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 13:32:00 GMT

Hi,

My plan is to position the Check Point device in bridge mode between the FortiGate firewall and the Aruba switch, and demonstrate the benefits of Check Point.

The FortiGate firewall and the Aruba switch are connected via LACP (Link Aggregation) and operate in trunk mode. Multiple VLANs are defined under this trunk. However, when I place the Check Point firewall between the two devices in bridge mode, no traffic passes through to me.

I have configured the VLANs under the Br1 interface on the Check Point device to match the VLANs defined on the FortiGate, but the result remains the same—no traffic is being received.

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 14:21:40 GMT

Hi @Madmaks

What does the Smartlog show?

What does #fw ctl zdebug + drop shows?

The picture is correct? Aruba and Forti sides are LACP, and the CP has only 1 Interface? Both side must be the same. "one-legged" bond wont't work in this situation.

Akos

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 14:38:52 GMT

When I run zdebug I could not see any drop. Smartlog show just showing log of mgmt interface.

Why do you think it won't work with a single interface? After all, that's what LACP is for. Even with a single interface, LACP will ensure that packets pass through one line.

The key point here is whether Check Point interferes with L2 traffic. For example, if it can only recognize IPv4, IPv6, and ARP traffic but not all traffic types, then that might be a reason for LACP not to work. Otherwise, I don’t see why it shouldn’t work. We can discuss this further

May be following solution will be help me, what about think?

Allow / Drop Ethernet Frames with Specific Protocols

By default, Security Gateway in the Bridge mode allows Ethernet frames that carry protocols other than IPv4 (0x0800), IPv6 (0x86DD), or ARP (0x0806) protocols.

Starting in R77.10, administrators can configure a Security Gateway in the Bridge mode to accept or drop Ethernet frames that carry specific protocols.

Note: In a cluster environment, this procedure must be performed on all members of the cluster.

Which Ethernet frames should be allowed/dropped	Instructions
Allow Ethernet frames only with IPv4, IPv6, and ARP protocols	Add this line to the $FWDIR/boot/modules/fwkern.conf file (spaces are not allowed): fwaccept_unknown_protocol=0 Reboot the Security Gateway.
Allow Ethernet frames with any protocol (other than IPv4, IPv6, or ARP) (default)	Add this line to the $FWDIR/boot/modules/fwkern.conf file (spaces are not allowed): fwaccept_unknown_protocol=1 Reboot the Security Gateway.

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Chris_Atkinson — Tue, 01 Oct 2024 15:20:53 GMT

The Check Point probably should have two bonds configured to participate in LACP for this topology irrespective of how many slave interfaces are up/down.

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 17:16:15 GMT

Are you suggesting I do LACP on Checkpoint?

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 17:37:42 GMT

Hi @Madmaks

And I think if you do a TCPDUMP on the CP, you see nothing.

Yes, you need to do a BOND on CheckPoint site:

Why?

Because the CheckPoint site can't negotiate on LACP, because neither the ETH4 nor ETH5 is not a member of a bond (LACP group). How can the "talp" LACP if is not configured?

Go further: if they never negotiate on LACP the traffic won't flow on a degradeted bond. This is my experience

Configure a simple bond, and see what happen.

Akos

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 17:45:54 GMT

Yes, I technically understand everything you mentioned.

Initially, I thought the same, but then I considered that if the Check Point is in bridge mode, it should also forward the LACP negotiation (L2) packets required for the link aggregation to work.

However, from what I understand now, in bridge mode, the Check Point does not forward these LACP negotiation packets, meaning it doesn't fully function as a true bridge.

Alright, I'll try what you suggested. Thanks

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 18:02:21 GMT

Hi @Madmaks

Yes I understood. and thanks for understanding me.

I think here is where the dog is buried:

When an IEEE 802.3ad aggregation is configured, link aggregation control protocol data units (LACPDUs) are exchanged between the server machine (host system) and the adjacent switch. Only the active channel, which could be either the primary channel or the backup adapter, exchanges LACPDU with the adjacent switch.

This is what doesn't happen.

Please keep me updated 🙂

Akos

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 18:19:47 GMT

Thanks for your explanation. I want to ask you something. Do you think another vendor (I prefer not to mention the name) doing a PoC with this customer could have accomplished this using the virtual wire feature? Do you have any thoughts on this.

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 18:27:35 GMT

Hi @Madmaks

I know this vendor, but I am not familiar with ther products. IEEE 802.3ad is a standard, and I thing nobody can bypass it. Rules are rules. 🙂

Akos

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 18:32:27 GMT

Based on this logic, do you think I also need to define the VLANs under the Bridge interface (Br1 and Br2) as Br1.100 and Br1.200, for example?

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 18:57:23 GMT

No you don't need to configure VLAN.

Check this SK: https://support.checkpoint.com/results/sk/sk34312

Akos

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 19:03:26 GMT

thank you.

Btw I found this link 🙂

https://community.checkpoint.com/t5/Security-Gateways/Is-that-possible-to-bypass-LACP-in-CheckPoint-with-Bridge-mode/m-p/84340#M6502

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

AkosBakos — Tue, 01 Oct 2024 19:09:59 GMT

But our brainstorming was worth the time. :-). I said the same with my words 🙂

Every word of Timothy are gold 🙂

Re: Problem that is bridge Mode between Aruba Switch and Fortigate

Madmaks — Tue, 01 Oct 2024 19:18:01 GMT

Thank you again.

In fact, if there is such an SK (https://support.checkpoint.com/results/sk/sk34312), there should definitely be an SK related to the topic we discussed as well.