Date: Fri, 27 Oct 1995 09:45:52 -0700 From: David Greenman <davidg@Root.COM> To: mikebo@tellabs.com Cc: wollman@lcs.mit.edu (Garrett A. Wollman), hackers@freebsd.org Subject: Re: 2.1.0-951020-SNAP: Major bug in NFS again! Message-ID: <199510271645.JAA00169@corbin.Root.COM> In-Reply-To: Your message of "Fri, 27 Oct 95 10:06:13 CDT." <199510271506.KAA00739@sunc210.tellabs.com>
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>Garret wrote: >> <<On Thu, 26 Oct 1995 17:07:33 -0500 (CDT), mikebo@tellabs.com said: >> > I do have a question: >> > Would a FreeBSD server always respond to a client from the same interface >> > on which it received a request - even though its route table has a >> > different route to the clients network? >> >> No. Source address != interface. If the source address is already >> set in the outgoing IP packet, ip_output() will not change it even if >> the packet goes out an interface which does not have that address on >> it. (Otherwise forwarding would not work!) >> >So, a multi-homed FreeBSD NFS server would behave the same as a multi- >homed Sun NFS server and adhere to the route table. That's what I >thought, but is contrary to some grumblings I've heard about the way Sun >serves NFS. Some people have sworn that the "proper" thing for the server >to do is send replies out the same interface that received the request - >evidently not caring whether it adhered to the route table or not. I think you might be confusing this a bit. As was said above, just because the packet goes out an interface because of a prefered route doesn't mean that it will have that interface's address. The problem you've been having is source address related, not specifically a route problem. I don't know what FreeBSD does for UDP NFS, but for TCP NFS I'm quite sure that the address used by the server is constant regardless of the route. If FreeBSD servers reply to NFS UDP packets the same way that the Sun machines do (packets always have the source address of the interface they are going out on), then FreeBSD would be broken, too, IMO. ...but again, I haven't tested this. -DG
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