> Source: [sk165656](https://support.checkpoint.com/results/sk/sk165656)

# sk165656 - "Pulse Secure" VPN and Cisco VPN clients connection issues when Endpoint Security Client Firewall blade is installed

| Property | Value |
|----------|-------|
| Solution ID | sk165656 |
| Date Created | 2020-03-08 |
| Last Modified | 2023-07-28 |
| Technical Level | General |
| Products | Endpoint Security |
| Versions | Cloud, E89.X, E88.X |
| OS | Windows |

## Symptoms

- * When Endpoint Security Client Firewall blades installed - After establishing VPN connection via 3rd party software, Pulse Secure VPN client, the user is experiencing connections issues. For example: Connection via "Putty" to a server that requires VPN connection fails.
* RDP connections to remote machine fails when Cisco VPN client installed alongside the Harmony Endpoint client including the Firewall blade.
* FTP connections are block or drop on additional network interfaces when Endpoint Security client is installed with Firewall blade and Network Protection is enabled on the Windows Server 2012 R2 and end-users are connected to any non-primary interface.
* Unable to RDP using Avanti (LANDesk) to machines when Endpoint Security client is installed with Firewall blade

## Cause

When third-party driver reinjects SYN-ACK packet, it's local address gets replaced, instead of virtual address the physical address is injected, therefore Windows Filtering Platform thinks that this is the new session, tries to establish it, but fails because session can't be initiated with SYN-ACK packet.

## Solution

Fix is included in E82.50 with additional configuration.  

To allowing some cases of 3rd-party VPN software to work properly enable special mode of packet handling in driver:   

1. Boot machine to Safe Mode without networking.
2. Open Registry Editor.
3. Go to "HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\vsdatant\\Parameters\\"
4. Create new DWORD value with the name *SynAckCheck*
5. Modify SynAckCheck value data to "1" (Decimal Base).
6. Reboot the machine.

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