Re: [PATCH 1/5] fwd: Clarify semantics of --host-lo-to-ns-lo

On Mon, Jul 13, 2026 at 02:39:35AM +0200, Stefano Brivio wrote:

Nits only (pretty much for the whole series, even though I have slightly more substantial remarks for 3/5 and 5/5, so I thought I'd point all of them out):

On Fri, 10 Jul 2026 16:56:07 +1000 David Gibson wrote:

...

The semantics of --host-lo-to-ns-lo as described in the man page don't quite make sense: It says without the option forwarded packets will appear to come _from_ the guest's public address, which is not usually true. Instead the packets will arrive *to* the guest's public address. The exact semantics are also a bit confusing in general.

Rewrite both the man page and code to clarify this. The new rule is that it redirects connections addressed to a host loopback address to the same loopback address in the guest. This is notionally different from what we had in two ways: * We can now deliver to nonstandard loopback addresses within the guest, not just the default one. This is technically a behavioural change, but I think will be less surprising behaviour. * The decision is now made on the original _destination_ address, rather than source address. That's different theoreically, but not in

theoretically

Oops, fixed. [snip]

...

.TP .BR \-\-host-lo-to-ns-lo -If specified, connections forwarded with \fB\-t\fR and \fB\-u\fR from -the host's loopback address will appear on the loopback address in the -guest as well. Without this option such forwarded packets will appear -to come from the guest's public address. +If specified, connections to a host loopback address forwarded with +\fB\-t\fR or \fB\-u\fR will be delivered to the same loopback address +on the guest. Without this option such connections are forwarded to +the guest's public address. This option is incompatible with +\fB--no-splice\fR.

Pre-existing, but still somewhat confusing: this is one part of the man page where we don't specify "guest or namespace", we just use "guest", and yet it's never a guest, it's always a namespace.

Should we just change all the occurrences of "guest" to "namespace" in this paragraph?

Good idea, done. For future reference, in cases where it's less obvious which namespace we're talking about, how do you feel about "guest namespace". -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson