# PPTP and GRE Tunneling Through NAT

You can configure NAT traversal support for GRE flows using simple translations (Basic NAT). Because PPTP uses an enhanced GRE encapsulation for the PPP payload, configuring for GRE flows also supports NAT traversal for PPTP tunnels.

| Note: Neither port translation (NAPT) nor Firewall traversal for GRE packets is supported for GRE flows.

When configured, the following types of translations are supported for GRE and PPTP tunnels:

- Inside source static simple translations (inbound and outbound)
- Outside source static simple translations (inbound and outbound)
- Inside source dynamic simple translations (inbound and outbound)
- Outside source dynamic simple translations (inbound and outbound)
- Combinations of the preceding translations (for example, twice NAT)