1.\" 2.\" Copyright (c) 2001, FreeBSD Inc. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice unmodified, this list of conditions, and the following 10.\" disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd May 16, 2006 30.Dt NG_ETF 4 31.Os 32.Sh NAME 33.Nm ng_etf 34.Nd Ethertype filtering netgraph node type 35.Sh SYNOPSIS 36.In netgraph.h 37.In netgraph/ng_etf.h 38.Sh DESCRIPTION 39The 40.Nm etf 41node type multiplexes and filters data between hooks on the basis 42of the ethertype found in an Ethernet header, presumed to be in the 43first 14 bytes of the data. 44Incoming Ethernet frames are accepted on the 45.Em downstream 46hook and if the ethertype matches a value which the node has been configured 47to filter, the packet is forwarded out the hook which was identified 48at the time that value was configured. 49If it does not match a configured 50value, it is passed to the 51.Em nomatch 52hook. 53If the 54.Em nomatch 55hook is not connected, the packet is dropped. 56.Pp 57Packets travelling in the other direction (towards the 58.Em downstream 59hook) are also examined and filtered. 60If a packet has an ethertype that matches one of the values configured 61into the node, it must have arrived in on the hook for which that value 62was configured, otherwise it will be discarded. 63Ethertypes of values other 64than those configured by the control messages must have arrived via the 65.Em nomatch 66hook. 67.Sh HOOKS 68This node type supports the following hooks: 69.Bl -tag -width ".Em downstream" 70.It Em downstream 71Typically this hook would be connected to a 72.Xr ng_ether 4 73node, using the 74.Em lower 75hook. 76.It Em nomatch 77Typically this hook would also be connected to an 78.Xr ng_ether 4 79type node using the 80.Em upper 81hook. 82.It Aq Em "any legal name" 83Any other hook name will be accepted and can be used as the match target 84of an ethertype. 85Typically this hook would be attached to 86a protocol handling node that requires and generates packets 87with a particular set of ethertypes. 88.El 89.Sh CONTROL MESSAGES 90This node type supports the generic control messages, plus the following: 91.Bl -tag -width 4n 92.It Dv NGM_ETF_GET_STATUS 93This command returns a 94.Vt "struct ng_etfstat" 95containing node statistics for packet counts. 96.It Dv NGM_ETF_SET_FILTER 97Sets the a new ethertype filter into the node and specifies the hook to and 98from which packets of that type should use. 99The hook and ethertype 100are specified in a structure of type 101.Vt "struct ng_etffilter" : 102.Bd -literal -offset 4n 103struct ng_etffilter { 104 char matchhook[NG_HOOKSIZ]; /* hook name */ 105 uint16_t ethertype; /* catch these */ 106}; 107.Ed 108.El 109.Sh EXAMPLES 110Using 111.Xr ngctl 8 112it is possible to set a filter in place from the command line 113as follows: 114.Bd -literal -offset 4n 115#!/bin/sh 116ETHER_IF=fxp0 117MATCH1=0x834 118MATCH2=0x835 119cat <<DONE >/tmp/xwert 120# Make a new ethertype filter and attach to the Ethernet lower hook. 121# first remove left over bits from last time. 122shutdown ${ETHER_IF}:lower 123mkpeer ${ETHER_IF}: etf lower downstream 124# Give it a name to easily refer to it. 125name ${ETHER_IF}:lower etf 126# Connect the nomatch hook to the upper part of the same interface. 127# All unmatched packets will act as if the filter is not present. 128connect ${ETHER_IF}: etf: upper nomatch 129DONE 130ngctl -f /tmp/xwert 131 132# something to set a hook to catch packets and show them. 133echo "Unrecognised packets:" 134nghook -a etf: newproto & 135# Filter two random ethertypes to that hook. 136ngctl 'msg etf: setfilter { matchhook="newproto" ethertype=${MATCH1} } 137ngctl 'msg etf: setfilter { matchhook="newproto" ethertype=${MATCH2} } 138.Ed 139.Sh SHUTDOWN 140This node shuts down upon receipt of a 141.Dv NGM_SHUTDOWN 142control message, or when all hooks have been disconnected. 143.Sh SEE ALSO 144.Xr netgraph 4 , 145.Xr ng_ether 4 , 146.Xr ngctl 8 , 147.Xr nghook 8 148.Sh HISTORY 149The 150.Nm 151node type was implemented in 152.Fx 5.0 . 153.Sh AUTHORS 154.An Julian Elischer Aq julian@FreeBSD.org 155