Checkpoint – Proxy ARP for manual NAT on VSX

Checkpoint – Proxy ARP for manual NAT on VSX

In my post Checkpoint – Automatic NAT vs Manual NAT I explained both types of NAT clarifying that the Manual NAT makes neccesary the Proxy ARP entry configuration. This example is for a Checkpoint VSX cluster scenario.

This is an example that was used:

The IP that should be configured to answer to ARP request is the 80.80.100.100 (No server in my environment has this IP configured but the Proxy ARP entry will allow the firewall to manage and NAT the packets sent to that IP).

The entry "links" the IP address with the MAC address of the interface that should manage the packet. There is a file that contains all that entrys: $FWDIR/conf/local.arp

So, we have to:

1. Configure the Policy Global Properties to make this work (only once)
2. Log in expert mode and edit the $FWDIR/conf/local.arp (if it does not exist, create it) for all cluster nodes.
3. Install the corresponding policy

Configure the Policy Global Properties

When "Merge manual proxy ARP configuration" is unchecked the local.arp file is ignored.
So ensure this option is checked:

Add the entry to the local.arp file

Change to the virtual system where the NAT is performed (this is for my perimetral FW – VS1):

[Expert@vsx1:0]# vsenv 1
Context is set to Virtual Device VSX1_EXTERNAL (ID 1).

This is my way to know the MAC address. Surely there are more (and or better) ways:

[Expert@vsx1:1]# ifconfig | grep 80.80.100 -B 1
wrp65       Link encap:Ethernet  HWaddr 00:22:F1:21:C0:0B
            inet addr:80.80.100.10  Bcast:80.80.100.255  Mask:255.255.255.0

Add the entry to the file:

[Expert@vsx1:1]# echo "80.80.100.100 00:22:f1:21:c0:0b" >> $FWDIR/conf/local.arp
[Expert@vsx1:1]# cat $FWDIR/conf/local.arp
80.80.100.100 00:22:f1:21:c0:0b

Be careful when adding the entry on all nodes:
Each of them have its own MAC address. Dont copy&paste the same line on all the local.arp files.

Install the corresponding policy

Install the policy of the affected virtual system:

Other scenarios

Be aware that this configuration is valid for virtual systems on a VSX cluster environment.
Check this official SK30197 for more scenarios.