.\" $OpenBSD: brconfig.8,v 1.2 1999/09/23 04:12:02 alex Exp $ .\" .\" Copyright (c) 1999 Jason L. Wright (jason@thought.net) .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by Jason L. Wright .\" 4. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED .\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE .\" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, .\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES .\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN .\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .Dd February 26, 1999 .Dt BRCONFIG 8 .Os .Sh NAME .Nm brconfig .Nd manipulate bridge interfaces .Sh SYNOPSIS .Nm brconfig .Ar -a .Nm brconfig .Ar bridge-name .Op Ar up .Op Ar down .Op Ar addr .Op Ar add interface-name .Op Ar delete interface-name .Op Ar maxaddr size .Op Ar timeout time .Op Ar static interface-name address .Op Ar deladdr address .Op Ar flush .Op Ar flushall .Op Ar discover interface-name .Op Ar -discover interface-name .Op Ar learn interface-name .Op Ar -learn interface-name .Op Ar link0 .Op Ar link1 .Op Ar -link0 .Op Ar -link1 .Op Ar ... .Sh DESCRIPTION The .Nm brconfig utility retrieves kernel state of bridge interfaces and allows user control of these bridges. In the first synopsis, the command will list the status of all bridges in the system. In the second, its command line consists of the name of a bridge and a set of operations to be performed on that bridge. The commands are executed in the order they were specified. If no command is specified in the second synopsis, the .Nm brconfig will display status information about the bridge. .Pp The available commands are: .Bl -tag -width Ds .It Ar up Start the bridge forwarding packets. .It Ar down Stop the bridge from forwarding packets. .It Ar addr Display the addresses that have been learned by the bridge. .It Ar add interface-name Add the interface named by .Ar interface-name as a member of the bridge. The interface is put into promiscuous mode so that it can receive every packet sent on the network. .It Ar delete interface-name Remove the interface named by .Ar interface-name from the bridge. Promiscuous mode is turned off for the interface when it is removed from the bridge. .It Ar del Alias for `delete'. .It Ar maxaddr size Set the address cache size to .Cm size . The default is 100 entries. .It Ar timeout time Set the timeout, in seconds, for addresses in the cache to .Cm time . The default is 240 seconds. If .Cm time is set to zero, then entries will not be expired. .It Ar static interface-name address Add a static entry into the address cache pointing to .Cm interface-name . Static entries are never aged out of the cache or replaced if the address is seen on a different interface. .It Ar deladdr address Delete an address from the cache. .It Ar flush Remove all dynamically learned addresses from the cache. .It Ar flushall Remove all addresses from the cache including static addresses. .It Ar discover interface Mark an interface so that packets are sent out of the interface if the destination port of the packet is unknown. If the bridge has no address cache entry for the destination of a packet, meaning that there is no static entry and no dynamically learned entry for the destination, the bridge will forward the packet to all member interfaces that have this flag set. This is the default for interfaces added to the bridge. .It Ar -discover interface Mark an interface so that packets are not sent out of the interface if the destination port of the packet is unknown. Turning this flag off means that the bridge will not send packets out of this interface unless the packet is a broadcast packet, multicast packet, or a packet with a destination address found on the interface's segment. This, in combination with static address cache entries, prevents potentially sensitive packets from being sent on segments that have no need to see the packet. .It Ar learn interface Mark an interface so that the source address of packets received from .Cm interface are entered into the address cache. This is the default for interfaces added to the bridge. .It Ar -learn interface Mark an interface so that the source address of packets received from .Cm interface are not entered into the address cache. .It Ar link0 Setting this flag stops all non-IP multicast packets from being forwarded by the bridge. .It Ar -link0 Clear the .Ar link0 flag on the bridge interface. .It Ar link1 Setting this flags stops all IP multicast packets from being forwarded by the bridge. .It Ar -link0 Clear the .Ar link1 flag on the bridge interface. .El .Sh EXAMPLES .Bl -tag -width brconfig .It Cm brconfig bridge0 add rl0 add xl0 up Add the Ethernet interfaces rl0 and xl0 to the bridge bridge0, and start the bridge forwarding packets. .It Cm brconfig bridge0 Retrieve a list of interfaces that are members of bridge0, and the addresses learned by the bridge. .It Cm brconfig bridge0 down Stop bridge0 from forwarding packets. .It Cm brconfig bridge0 delete xl0 Remove the interface xl0 from the bridge bridge0. .It Cm brconfig bridge0 flush Flush all dynamically learned addresses from the address cache. .It Cm brconfig bridge0 flushall Remove all addresses, including static addresses, from the address cache. .It Cm brconfig bridge0 -learn xl0 static xl0 8:0:20:1e:2f:2b .It Cm brconfig bridge0 -discover xl0 The examples above mark the xl0 interface so that it will not learn addresses and adds a static entry for the host 8:0:20:1e:2f:2b on the xl0 segment. Finally, xl0 is marked so that it will not receive packets with destinations not found in the address cache of bridge0. This setup is the most secure, and means that bogus MAC addresses seen by the xl0 side of the bridge will not be propagated to the rest of the network. Also, no packets will be sent on xl0 segment by the bridge unless they are broadcast packets or are for 8:0:20:1e:2f:2b. .El .Sh SEE ALSO .Xr bridge 4 , .Xr ifconfig 8 .Sh HISTORY .Nm brconfig first appeared in .Ox 2.5 . .Sh AUTHOR The .Xr brconfig 8 command and the .Xr bridge 4 kernel interface were written by Jason L. Wright as part of an undergraduate independent study at the University of North Carolina at Greensboro. .Sh BUGS There are some rather special network interface chipsets which will not work in a bridge configuration. Some, like the Lite-On PNIC (see .Xr pn 4 ), have serious flaws when running in promiscuous mode, and others, like the TI ThunderLAN (see .Xr tl 4 ), receive their own transmissions, which makes the address learning code ineffective. Most other chipsets work fine though.