2d741f33bd
Currently, this will still hash the default (all zero) hostuuid and potentially arrive at a MAC address that has a high chance of collision if another interface of the same name appears in the same broadcast domain on another host without a hostuuid, e.g., some virtual machine setups. Instead of using the default hostuuid, just treat it as a failure and generate a random LA unicast MAC address. Reviewed by: bz, gbe, imp, kbowling, kp MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D29788
81 lines
2.7 KiB
Groff
81 lines
2.7 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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.\"
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.\" Copyright (C) 2021 Kyle Evans <kevans@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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.\" DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 1, 2021
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.Dt ETHER_GEN_ADDR 9
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.Os
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.Sh NAME
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.Nm ether_gen_addr
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.Nd "generate an arbitrary MAC address for use"
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/socket.h
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.In net/if.h
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.In net/if_var.h
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.In net/ethernet.h
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.Ft void
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.Fn ether_gen_addr "struct ifnet *ifp" "struct ether_addr *hwaddr"
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.Sh DESCRIPTION
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The
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.Fn ether_gen_addr
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function generates an arbitrary MAC address for use by an ethernet interface
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that does not have an assigned address.
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.Pp
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By default,
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.Nm
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attempts to generate a stable MAC address using the hostid of the jail that
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the
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.Ar ifp
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is being added to.
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During early boot, the hostid may not be set on machines that haven't yet
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populated
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.Pa /etc/hostid ,
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or on machines that do not use
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.Xr loader 8 .
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.Pp
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.Nm
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can fail to derive a MAC address due to memory allocation failure, or because
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the hostid has not been populated.
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In these cases, a locally-administered unicast MAC address will be randomly
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generated and returned via the
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.Ar hwaddr
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parameter.
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.Pp
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If
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.Nm
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succeeds, then it will return a MAC address in the FreeBSD Foundation OUI,
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.Dq 58:9c:fc ,
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via the
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.Ar hwaddr
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parameter.
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.Sh AUTHORS
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This manual page was written by
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.An Kyle Evans Aq Mt kevans@FreeBSD.org .
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