A computer system authenticates a logical port for a virtual machine. A logical network maintains logical network data for a logical switch having the logical port. A virtual switch identifies a logical port authentication request for the virtual machine and transfers the logical port authentication request. A logical port authenticator receives the logical port authentication request and transfers the logical port authentication request for delivery to an authentication database. The logical port authenticator receives a logical port authentication response transferred by the authentication database that grants the logical port authentication request for the virtual machine and transfers authorization data for the logical port. The virtual switch transfers user data for the virtual machine when the virtual machine uses the logical port responsive to the authorization data.