Copyright (c) 1999 Jason L. Wright (jason@thought.net)
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.Dd February 26, 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 SIOCBRDGIFS
q Li "struct ifbifconf" Retrieve member interface list from a bridge. This request takes an .Ar ifbifconf structure (see below) as a value-result parameter. The .Ar ifbic_len field should be initially set to the size of the buffer pointed to by .Ar ifbic_buf . On return it will contain the length, in bytes, of the configuration list. Alternatively, if the .Ar ifbic_len passed in is set to 0, SIOCBRDGIFS will set .Ar ifbic_len to the size that .Ar ifbic_buf needs to be to fit the entire configuration list, and will not fill in the other parameters. This is useful for determining the exact size that .Ar ifbic_buf needs to be in advance.
p The argument structure is defined as follows: d -literal -offset indent struct ifbreq { char ifbr_name[IFNAMSIZ]; /* bridge name */ char ifbr_ifsname[IFNAMSIZ]; /* member name */ u_int32_t ifbr_ifsflags; /* member flags */ }; #define IFBIF_LEARNING 0x1 /* ifs can learn addrs */ #define IFBIF_DISCOVER 0x2 /* ifs gets fwd'd pkts */ struct ifbifconf { char ifbic_name[IFNAMSIZ]; /* bridge name */ u_int32_t ifbic_len; /* buffer size */ union { caddr_t ifbicu_buf; /* buffer */ struct ifbreq *ifbicu_req; } ifbic_ifbicu; #define ifbic_buf ifbic_ifbicu.ifbicu_buf #define ifbic_req ifbic_ifbicu.ifbicu_req }; .Ed t Dv SIOCBRDGADD
q Li "struct ifbreq" Add the interface named in .Ar ifbr_ifsname to the bridge named in .Ar ifbr_name . t Dv SIOCBRDGDEL
q Li "struct ifbreq" Delete the interface named in .Ar ifbr_ifsname from the bridge named in .Ar ifbr_name . t Dv SIOCBRDGSIFFLGS
q Li "struct ifbreq" Set the bridge member interface flags for the interface named in .Ar ifbr_ifsname attached to the bridge .Ar ifbr_name . t Dv SIOCBRDGGIFFLGS Retrieve the bridge member interface flags for the interface named in .Ar ifbr_ifsname attached to the bridge .Ar ifbr_name . t Dv SIOCBRDGRTS
q Li "struct ifbaconf" Retrieve the address cache of the bridge named in .Ar ifbac_name . This request takes an .Ar ifbaconf structure (see below) as a value result parameter. The .Ar ifbac_len field should be initially set to the size of the buffer pointed to by .Ar ifbac_buf . On return, it will contain the length, in bytes, of the configuration list. Alternatively, if the .Ar ifbac_len passed in is set to 0, SIOCBRDGRTS will set it to the size that .Ar ifbac_buf needs to be to fit the entire configuration list and not fill in the other parameters. As with SIOCBRDGIFS, this is useful for determining the exact size that .Ar ifbac_buf needs to be in advance.
p The argument structure is defined as follows: d -literal -offset indent struct ifbareq { char ifba_name[IFNAMSIZ]; /* bridge name */ char ifba_ifsname[IFNAMSIZ]; /* dest ifs */ u_int8_t ifba_age; /* addr age */ u_int8_t ifba_flags; /* addr age */ struct ether_addr ifba_dst; /* dest addr */ }; #define IFBAF_TYPEMASK 0x03 /* address type mask */ #define IFBAF_DYNAMIC 0x00 /* dynamically learned */ #define IFBAF_STATIC 0x01 /* static address */ struct ifbaconf { char ifbac_name[IFNAMSIZ]; /* bridge name */ u_int32_t ifbac_len; /* buffer size */ union { caddr_t ifbacu_buf; /* buffer */ struct ifbareq *ifbacu_req; } ifbac_ifbacu; #define ifbac_buf ifbac_ifbacu.ifbacu_buf #define ifbac_req ifbac_ifbacu.ifbacu_req }; .Ed t Dv SIOCBRDGSADDR
q Li "struct ifbareq" Add an entry, manually, to the address cache for the bridge named in .Ar ifba_name . The address and its associated interface and flags are set in the .Ar ifba_dst , .Ar ifba_ifsname , .Ar ifba_flags fields, respectively. t Dv SIOCBRDGDADDR
q Li "struct ifbareq" Delete an entry from the address cache of the bridge named in .Ar ifba_name . Entries are deleted strictly based on the address field .Ar ifba_dst . t Dv SIOCBRDGSCACHE
q Li "struct ifbcachereq" Set the maximum address cache size for the bridge named in .Ar ifbc_name to .Ar ifbc_size entries.
p The argument structure is as follows: d -literal -offset indent struct ifbcachereq { char ifbc_name[IFNAMSIZ]; /* bridge */ u_int32_t ifbc_size; /* size */ }; .Ed t Dv SIOCBRDGGCACHE
q Li "struct ifbcachereq" Retrieve the maximum size of the address cache for the bridge .Ar ifbc_name . t Dv SIOCBRDGSTO
q Li "struct ifbcachetoreq" Set the time, in seconds, that addresses which have not been seen on the network (transmitted a packet) remain in the cache. If the time is set to zero, no aging is performed on the address cache. The argument structure is as follows: d -literal -offset indent struct ifbcachetoreq { char ifbct_name[IFNAMSIZ]; /* bridge */ u_int32_t ifbct_time; /* time */ }; .Ed t Dv SIOCBRDGGTO
q Li "struct ifbcachetoreq" Retrieve the address cache expiration time (see above). .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. t Bq Eq ENOMEM Memory could not be allocated for an interface or cache entry 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. t Bq Eq EFAULT The buffer used in a SIOCBRDGIFS or SIOCBRDGRTS request points outside of the process's allocated address space. .El .Sh SEE ALSO .Xr errno 2 , .Xr ioctl 2 , .Xr ipf 4 , .Xr netintro 4 , .Xr brconfig 8 .Sh HISTORY The .Xr brconfig 8 command and the .Xr bridge 4 kernel interface 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 <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.