Proxy Operation

VMware Telnet Extension Command Negotiation lists the extension commands to negotiate proxy support.

VMware Telnet Extension Command Negotiation

Command	Code
DO-PROXY direction serviceUri A virtual machine request for the proxy to do forwarding operations over the connection. The virtual machine sends a DO-PROXY request before any content is exchanged between the virtual machine and the remote system. direction and serviceURI correspond to the VirtualSerialPortURIBackingInfo properties in the virtual serial port configuration. (See the vSphere API Reference for information about the VirtualSerialPortURIBackingInfo data object.) direction is either “C” (client) or “S” (server). If the direction indicates that the virtual machine is acting as a client, serviceUri identifies a remote system and the proxy initiates a connection with the remote system. If the direction indicates that the virtual machine is acting as a server, serviceUri identifies the network socket on the host on which the virtual machine runs. In this case, the virtual machine will accept a connection initiated by a remote system (using the proxy). If possible, the proxy should also handle port control options, as specified by RFC 2217.   IAC SB VMWARE-TELNET-EXT DO-PROXY direction uri IAC SE 255 250 232 70 direction uri 255 240	70
WILL-PROXY A proxy response to indicate that it will do forwarding operations.   IAC SB VMWARE-TELNET-EXT WILL-PROXY IAC SE 255 250 232 71 255 240	71
WON’T-PROXY A proxy response to indicate that it will not do forwarding operations.   IAC SB VMWARE-TELNET-EXT WON’T-PROXY IAC SE 255 250 232 73 255 240	73