1. Types of NAT Policies
Palo Alto Networks firewalls support various NAT types to accommodate different network requirements:
-
Dynamic IP and Port (DIPP) NAT:
Translates multiple private IP addresses to a single public IP address by using different source ports. Commonly used for outbound internet access.
-
Dynamic IP NAT:
Translates private IP addresses to a pool of public IP addresses without changing the source port.
-
Static NAT:
Provides a one-to-one mapping between a private IP address and a public IP address. Useful for inbound access to internal servers.
-
Destination NAT:
Translates the destination IP address of incoming traffic to direct it to the appropriate internal server.
-
Bi-Directional NAT:
Combines both source and destination NAT, allowing for two-way communication between internal and external hosts.
-
No NAT:
Specifies traffic that should not undergo NAT. Useful for internal communications that don't require address translation.
For more details, refer to the
NAT Policy Overview
.
2. Troubleshooting NAT Policies
Effective troubleshooting of NAT policies involves several steps:
-
Verify NAT Rule Order:
NAT rules are processed top-down. Ensure that more specific rules are placed above general ones.
-
Check NAT Rule Matching:
Use the CLI command
test nat-policy-match
to simulate and verify which NAT rule a particular traffic flow would match.
-
Monitor Traffic Logs:
Navigate to
Monitor > Logs > Traffic
and add the "NAT Applied" column to see if NAT was applied to specific sessions.
-
Inspect ARP Entries:
Ensure that the firewall is responding to ARP requests for NAT addresses. If not, verify that the NAT IPs are in the same subnet as the interface or configure appropriate proxy ARP settings.
-
Review Routing:
Confirm that routes exist for both pre-NAT and post-NAT addresses, ensuring proper traffic flow.
-
Check Security Policies:
Remember that security policies are evaluated based on pre-NAT IP addresses but post-NAT zones. Ensure that policies are correctly configured to allow desired traffic.
For a comprehensive guide, consult the
Guide for Troubleshooting NATs & Security Policies
.