CODEWITHSUNDEEP
tcpwindows-10vpnrdp
user1345414
user1345414

Reputation: 3865

No SYN+ACK response in the VPN tunel

There are two Windows10 PCs.

Both PCs are connected VPN even being connected phisical LAN.

I'm trying to have RDP connection between PC-A and PC-B for each direction as VPN connection is estblished.

However,RDP is allowed only one direction.

PC-A >>> PC-B is OK

PC-A <<< PC-B isn't OK

I captured packet each PC and each direction for the VPN interface.

The packet at PC-B in succeeded case shows client Hello after TCP's SYN and SYN+ACK.

However,the packet at PC-A in failure case doesn't show client Hello and even doesn't respond SYN+ACK.

So TCP Retransmission is sent three times from PC-B.

Does anyone know why PC-A doesn't respond SYN+ACK ?

PC-A can respond SYN+ACK When they are disconnected from VPN ,the phisical LAN alternatively works.

It't doesn't seem it is coused by VPN itself.I can have one direction of RDP even VPN is estblished.

Upvotes: 7

Views: 995

Answers (2)

Michael Krasjaq
Michael Krasjaq

Reputation: 53

Include public peer IP to the ACLs. Due to the natting, the return leg of the handshake was being sent using the public peer IP, hence after adding the public peer IP to the ACLs it should work.

Upvotes: 1

tetouani63
tetouani63

Reputation: 47

I guess PC-A Firewall is blocking the incoming connections.

Have you checked the rules ?

Upvotes: 0

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