This article discusses the UDP port used for IKE traffic from a VPN client to server.
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In order to set up a VPN connection, IKE (Internet Key Exchange) must be used to set up a secure tunnel between the VPN client and server. IKE uses UDP port 500 for traffic from the VPN client to the server.
UDP Port 500
UDP port 500 is used for IKE traffic from VPN client to server.
UDP Port 4500
IKE traffic from VPN client to server uses UDP port 4500. This is the default port for IKE traffic.
The answer is that IKE traffic from VPN Client to Server uses UDP port 500.