Reference Manual

NAME
simplex - specify a simplex (uni-directional) network interface
SYNOPSIS
simplex [ifn]
DESCRIPTION
Network adapters connecting to hybrid cable modem services and satellite services never send packets to the Internet. Instead, outgoing traffic is sent via a DUN connection and the network adapter receives the response packets.

Command simplex is used to specify which NAT32 interface (if any) is to operate in this mode. Argument ifn can have the following values:

0 no simplex adapter
1..8 Network Interface number
If argument ifn is omitted, the current simplex interface number is printed.
NOTES
Traffic from a simplex adapter is modified to make it appear as if it had arrived at the Primary Interface. The modification is applied after adapter statistics have been updated.
SEE ALSO
ipmap, netcfg, ns, pmap