Date: Mon, 28 Apr 2003 11:26:24 -0400 (EDT) From: Robert Watson <rwatson@freebsd.org> To: Martin Blapp <mb@imp.ch> Cc: freebsd-net@freebsd.org Subject: Re: Implementing SO_BINDTODEVICE Message-ID: <Pine.NEB.3.96L.1030428112253.21738L-100000@fledge.watson.org> In-Reply-To: <20030418193305.S6156@cvs.imp.ch>
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On Fri, 18 Apr 2003, Martin Blapp wrote: > How difficult would it be to implement SO_BINDTODEVICE on FreeBSD ? I > need the to make is possible to run more than one instance of dhclient > on one host with more than one NIC. > > We would need this to support removable devices properly. > > There is a tool called omshell which should be able to change variables > so the interface is added to the lists. Unfortunatly the documentation > is bad and I only found hooks to dhcpd. Hmm. My impression was that dhclient used solely BPF descriptors on FreeBSD to perform interface-specific DHCP client communications, and that SO_BINDTODEVICE was used only in the DHCP server? BPF requires you to specifically identify an interface to bind to, as it's an interface-layer communications primitive. Last time I tried, the only real issue in using dhclient on multiple interfaces was making sure that pid files didn't collide, but that was several years ago, things could easily have changed. What semantics does SO_BINDTODEVICE offer? Normally, IP sockets make IP address binding and routing decisions based on the process optionally specifying IP addresses for local binding, and based on the destination of a connection/transmission. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Network Associates Laboratories
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