Differential D20044 Diff 57162 head/share/man/man4/tap.4

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head/share/man/man4/tap.4

	.\" $FreeBSD$			.\" $FreeBSD$
	.\" Based on PR#2411			.\" Based on PR#2411
	.\"			.\"
	.Dd November 29, 2017			.Dd April 29, 2019
	.Dt TAP 4			.Dt TAP 4
	.Os			.Os
	.Sh NAME			.Sh NAME
	.Nm tap			.Nm tap
	.Nd Ethernet tunnel software network interface			.Nd Ethernet tunnel software network interface
	.Sh SYNOPSIS			.Sh SYNOPSIS
	.Cd device tap			.Cd device tuntap
	.Sh DESCRIPTION			.Sh DESCRIPTION
	The			The
	.Nm			.Nm
	interface is a software loopback mechanism that can be loosely			interface is a software loopback mechanism that can be loosely
	described as the network interface analog of the			described as the network interface analog of the
	.Xr pty 4 ,			.Xr pty 4 ,
	that is,			that is,
	.Nm			.Nm
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	.Dq control			.Dq control
	interface.			interface.
	.Pp			.Pp
	The network interfaces are named			The network interfaces are named
	.Dq Li tap0 ,			.Dq Li tap0 ,
	.Dq Li tap1 ,			.Dq Li tap1 ,
	etc., one for each control device that has been opened.			etc., one for each control device that has been opened.
	These Ethernet network interfaces persist until			These Ethernet network interfaces persist until
	.Pa if_tap.ko			.Pa if_tuntap.ko
	module is unloaded, or until removed with "ifconfig destroy" (see below).			module is unloaded, or until removed with "ifconfig destroy" (see below).
	.Pp			.Pp
	.Nm			.Nm
	devices are created using interface cloning.			devices are created using interface cloning.
	This is done using the			This is done using the
	.Dq ifconfig tap Ns Sy N No create			.Dq ifconfig tap Ns Sy N No create
	command.			command.
	This is the preferred method of creating			This is the preferred method of creating
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	such as			such as
	.Tn VMware			.Tn VMware
	and			and
	.Xr ssh 1 .			.Xr ssh 1 .
	It therefore defaults to being enabled until further notice.			It therefore defaults to being enabled until further notice.
	.Ef			.Ef
	.Pp			.Pp
	Control devices (once successfully opened) persist until			Control devices (once successfully opened) persist until
	.Pa if_tap.ko			.Pa if_tuntap.ko
	is unloaded or the interface is destroyed.			is unloaded or the interface is destroyed.
	.Pp			.Pp
	Each interface supports the usual Ethernet network interface			Each interface supports the usual Ethernet network interface
	.Xr ioctl 2 Ns s			.Xr ioctl 2 Ns s
	and thus can be used with			and thus can be used with
	.Xr ifconfig 8			.Xr ifconfig 8
	like any other Ethernet interface.			like any other Ethernet interface.
	When the system chooses to transmit			When the system chooses to transmit
	▲ Show 20 Lines • Show All 183 Lines • ▼ Show 20 Lines
	letting them pile up.			letting them pile up.
	.Pp			.Pp
	The			The
	.Nm			.Nm
	device can also be used with the VMware port as a replacement			device can also be used with the VMware port as a replacement
	for the old			for the old
	.Em VMnet			.Em VMnet
	device driver.			device driver.
	The driver uses the minor number
	to select between
	.Nm
	and
	.Nm vmnet
	devices.
	.Em VMnet
	minor numbers begin at
	.Va 0x800000
	+
	.Va N ;
	where
	.Va N
	is a
	.Em VMnet
	unit number.
	In this case the control device is expected to be
	.Pa /dev/vmnet Ns Sy N ,
	and the network interface will be
	.Sy vmnet Ns Ar N .
	Additionally,
	.Em VMnet			.Em VMnet
	devices do not			devices do not
	.Xr ifconfig 8			.Xr ifconfig 8
	themselves down when the			themselves down when the
	control device is closed.			control device is closed.
	Everything else is the same.			Everything else is the same.
	.Pp			.Pp
	In addition to the above mentioned			In addition to the above mentioned
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