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diff --git a/share/man/man4/bridge.4 b/share/man/man4/bridge.4 new file mode 100644 index 0000000..5482c0e --- /dev/null +++ b/share/man/man4/bridge.4 @@ -0,0 +1,65 @@ +.\" +.\" $Id$ +.\" +.Dd Sep 28, 1998 +.Dt BRIDGE 4 +.Os +.Sh NAME +.Nm bridge +.Nd Bridging support +.Sh DESCRIPTION +Starting from version 2.2.8, FreeBSD supports bridging on ethernet-type +interfaces. This is achieved using the following option +.Bd -literal + options BRIDGE +.Ed + +in the kernel config file, and is controlled by two +.Nm sysctl +variables: +.Bd -literal + net.link.ether.bridge +.Ed + +Set to 1 to enable bridging, set to 0 to disable it +.Bd -literal + net.link.ether.bridge_ipfw +.Ed + +Set to 1 to enable +.Nm ipfw +filtering on bridged packets. Note that +.Nm ipfw +rules only apply +to IP packets. Non-IP packets are subject to the default +.Nm ipfw +rule (number 65535) which must be an +.Ar allow +rule if we want ARP and other non-IP packets to flow through the +bridge. + + +.Sh BUGS +.Pp +Care must be taken not to construct loops in the bridge topology. +The kernel supports only a primitive form of loop detection, by disabling +some interfaces when a loop is detected. No support for a daemon running the +spanning tree algorithm is currently provided. +.Pp +With bridging active, interfaces are in promiscuous mode, +thus causing some load on the system to receive and filter +out undesired traffic. +.Pp +Extended functionality to enable bridging selectively on clusters +of interfaces is still in the works. +.Pp +Not all interface support bridging -- at the moment it works for +``ed'', ``de'', ``ep'', ``fxp'', ``lnc'' interfaces. +.Sh SEE ALSO +.Xr ip 4 , +.Xr ipfw 8 , +.Xr sysctl 8 . +.Sh HISTORY +.Nm +bridging has been introduced in FreeBSD 2.2.8 +by Luigi Rizzo <luigi@iet.unipi.it>. |