When you use SNAT (Source Network Address Translation) over an IPSec tunnel, you need to ensure that the SNAT IP address is within the remote subnet's address range. In your configuration, the SNAT IP address is 192.168.77.1/32, which is not within the remote subnet's address range (172.17.17.9/32)

Potential Causes and Solutions:

    Incorrect NAT Rule Configuration:
        Source Network: Double-check that the "Source Network" in the SNAT rule accurately matches the local subnet (192.168.77.1/32) where communication initiates.
        Translated Address: Verify that the "Translated To" address matches the public IP address assigned to the SNAT-enabled interface on the Sangfor device. Avoid using a subnet or internal IP address here.
        Interface Selection: Ensure the SNAT rule applies to the correct interface that handles traffic going through the IPSec tunnel.

    Routing Issues:
        Static Routes: If static routes are used, confirm that they correctly direct traffic destined for the remote subnet (172.17.17.9/32) to the IPSec tunnel interface.
        Dynamic Routing Protocols: If dynamic routing protocols like OSPF or BGP are employed, verify that they're configured to propagate routing information for the remote subnet and that they converge properly.

    Firewall Rules:
        Allow Traffic: On both the local and remote sides of the tunnel, allow incoming and outgoing traffic from the translated source address (the public IP of the SNAT interface) to the remote subnet (172.17.17.9/32).
        Port Restrictions: If specific ports or applications are involved, ensure firewall rules permit communication on those ports or protocols.

    IPSec Tunnel Status:
        Verify Connectivity: Double-check that the IPSec tunnel is established and active. Use ping or traceroute commands from the local network to the remote subnet to confirm reachability.
        Encryption and Authentication: Ensure proper encryption and authentication settings on both tunnel endpoints. If using pre-shared keys, confirm they match exactly.

Additional Troubleshooting Tips:

    Logging and Debugging: Enable logging on the Sangfor device and the IPSec endpoints to capture detailed information about NAT translations, routing decisions, and potential errors.
    Test Connectivity Incrementally: Isolate potential issues by testing connectivity within isolated network segments (e.g., between the local network and the Sangfor device, then between the Sangfor device and the IPSec endpoint).
    Consult Sangfor Documentation: Refer to the official Sangfor documentation for your specific model and version for detailed SNAT configuration and troubleshooting steps.

Example Configuration (assuming Sangfor NGAF):

    Create a SNAT rule:
        Name: My_SNAT_Rule
        Source Network: 192.168.77.1/32
        Service: Any (if applicable to all traffic)
        Translated To: Public_IP_of_SNAT_Interface
        Interface: Interface_for_IPSec_Tunnel

    Verify firewall rules allowing traffic from the "Translated To" address (Public_IP_of_SNAT_Interface) to the remote subnet.

    Check static routes or dynamic routing protocol convergence as needed.

Remember to replace placeholders with your specific settings and adapt the steps based on your Sangfor model and network configuration.

I hope this comprehensive response helps you resolve the SNAT issue. Feel free to share any additional details about your setup, and I'll do my best to assist further.

There is wrong with your routing. Please verify your default route and policy base routing configuration.

Make that the SNAT IP address is inside the address range of the remote network before using SNAT (Source Network Address Translation) via an IPSec tunnel. The SNAT IP address in your configuration is 192.168.77.1/32, which is outside of the address range (172.17.17.9/32) of the remote subnet.

Set up SNAT on your firewall or local network device to transform outgoing packet source IP address to 192.168.77.1.
Make that the IPSec tunnel is set up correctly to permit traffic to flow from the remote network (172.17.17.9/32) to the local subnet (192.188.77.1/32).
Make that the routing is configured properly to send traffic over the IPSec tunnel that is meant for the distant subnet.
It's crucial to remember that the precise procedures for configuring SNAT over an IPSec tunnel can change based on the hardware and software you're utilizing.

Hello, Would you kindly send us the configuration information, which includes, among other things, information on the network, IPSec, and SNAT?
It will help us comprehend the issue and find a solution because from what you give us is not a complete information. Better to give us more info regarding your issues