6.7

Server and Client Connections for Named Pipe and Network Serial Ports
You can select a client or server connection for serial ports. Your selection determines whether the
system waits for a connection or initiates it. Typically, to control a virtual machine over a serial port, you
select a server connection. This selection lets you control the connections, which is useful if you connect
to the virtual machine only occasionally. To use a serial port for logging, select a client connection. This
selection lets the virtual machine connect to the logging server when the virtual machine starts and to
disconnect when it stops.
Supported Serial Ports
When you use a physical serial port for serial port passthrough from an ESXi host to a virtual machine,
serial ports that are integrated into the motherboard are supported. A virtual machine can use up to 32
serial ports.
Unsupported Serial Ports
When you use a physical serial port for serial port passthrough from an ESXi host to a virtual machine,
the serial ports connected through USB are not supported for serial port passthrough. They might be
supported by USB passthrough from an ESXi host to a virtual machine. See USB Configuration from an
ESXi Host to a Virtual Machine.
In addition, you cannot use Migration with VMotion when you use a physical serial port for serial
passthrough.
Adding a Firewall Rule Set for Serial Port Network Connections
If you add or configure a serial port that is backed by a remote network connection, ESXi firewall settings
can prevent transmissions.
Before you connect network-backed virtual serial ports, you must add one of the following firewall rule
sets to prevent the firewall from blocking communication:
n
VM serial port connected to vSPC. Use to connect the serial port output through a network with the
Use virtual serial port concentrator option enabled to allow only outgoing communication from the
host.
n
VM serial port connected over network. Use to connect the serial port output through a network
without the virtual serial port concentrator.
Important Do not change the allowed IP list for either rule set. Updates to the IP list can affect other
network services that might be blocked by the firewall.
For details about allowing access to an ESXi service through the firewall, see the vSphere Security
documentation.
Configure Virtual Machine Communication Interface Firewall
You can configure the virtual machine Communication Interface firewall (VMCI) to restrict virtual machines
accessing the hypervisor-based services and VMCI-based services.
vSphere Virtual Machine Administration
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