Copyright (c) 1999 Jason L. Wright (jason@thought.net)
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.Dd January 14, 1999 .Dt BRIDGE 4 .Os .Sh NAME .Nm bridge .Nd Ethernet bridge interface .Sh SYNOPSIS .Cd pseudo-device bridge 2 .Sh DESCRIPTION The .Nm bridge device allows an Ethernet bridge to be created between two or more interfaces. The bridges provided by this interface are learning bridges with the ability to do IP filtering, see .Xr ipf 4 , Ns before packets are forwarded by the bridge. .Sh IOCTLS A .Nm bridge interface responds to all of the .Xr ioctl 2 calls specific to other interfaces listed in .Xr netintro 4 . The following .Xr ioctl 2 calls are specific to .Nm bridge devices. They are defined in .Aq Pa sys/sockio.h .
p l -tag -width SIOCBRDGIDX t Dv SIOCBRDGIDX
q Li "struct ifbreq" Retrieve a member interface from a bridge by index number (zero based). The argument structure is defined as follows: d -literal -offset indent struct ifbreq { char ifbname[IFNAMSIZ]; /* bridge interface */ char ifsname[IFNAMSIZ]; /* member interface */ u_int32_t index; /* interface index */ }; .Ed
p To get a list of interface members, set index to zero, and perform sucessive .Xr ioctl 2 calls with increasing values of index. When the call returns ENOENT, there are no more interface members. t Dv SIOCBRDGADD
q Li "struct ifbreq" Add the interface named in ifsname to the bridge named in ifbname. t Dv SIOCBRDGDEL
q Li "struct ifbreq" Delete the interface named in ifsname from the bridge named in ifbname. t Dv SIOCBRDGRT
q Li "struct ifbrtreq" Retrieve a list of routes by index number (zero based). The argument structure is defined as follows: d -literal -offset indent struct ifbrtreq { char ifbname[IFNAMSIZ]; /* bridge interface */ u_int32_t index; /* iteration index */ struct ether_addr dst; /* destination addr */ char ifsname[IFNAMSIZ]; /* destination ifs */ u_int16_t age; /* route age */ }; .El .Sh ERRORS If the .Xr ioctl 2 call fails, .Xr errno 2 is set to one of the following values: l -tag -width Er t Bq Eq ENOENT For an add request, this means that the named interface is not configured into the system. For delete operation, it means that the named interface is not a member of the bridge. For an interface list or route list request, it means that there is no route or interface that corresponds to the given index number. t Bq Eq ENOMEM Memory could not be allocated for an interface to be added to the bridge. t Bq Eq EEXIST The named interface is already a member of the bridge. t Bq Eq EBUSY The named interface is already a member of another bridge. t Bq Eq EINVAL The named interface is not an Ethernet interface. t Bq Eq ENETDOWN The named interface is not ready for receiving packets. t Bq Eq EPERM Super-user privilege is required to add and delete interfaces to and from bridges and to set the bridge interface flags. .El .Sh SEE ALSO .Xr errno 2 , .Xr ioctl 2 , .Xr ipf 4 , .Xr netintro 4 , .Xr brconfig 8 .Sh AUTHOR The .Xr brconfig 8 command and the .Xr bridge 4 kernel interface were written by Jason L. Wright <jason@thought.net> as part of an undergraduate indenpendent study at the University of North Carolina at Greensboro. .Sh BUGS There is currently no loop detection. Care must be taken to make sure that loops are not created when a bridge is brought up. .Sh HISTORY The .Xr brconfig 8 command and the .Xr bridge 4 kernel interface first appeared in .Ox 2.5 .