Darren Reed writes:
> James Carlson wrote:
> > Darren Reed writes:
> >   
> >> James Carlson wrote:
> >>     
> >>> It's the usual UDP application problem: if you're a UDP-based server,
> >>> then you're supposed to use the same IP address and port as the source
> >>> values in your reply as the client originally used in his destination.
> >>>   
> >>>       
> >> The question in my mind was: why can't the IKE daemon use a single IP 
> >> address -
> >> why does it need to use "every" address?
> >>     
> >
> > Because clients can send packets to "any" address.
> >   
> 
> But how do they choose which one to send to?
> 
> Do they just pick the other end of the tunnel?

I'm confused.  Why does it matter?

This is the IKE daemon we're talking about, not the Sun-specific
punchin code.  The IKE daemon is general-purpose.  It has to work on
any Solaris system using IPsec, whether or not it has tunnels, and
regardless of the number of configured IP interfaces.

If the system is multi-homed, the server needs to obey the source
address selection requirements, which means that it needs to select a
source based on the destination that the client originally used --
which, on a multi-homed system, can be *any* of the configured
addresses on the system.

And it's the server-side we're talking about.  The client side has no
such problems; it can just send to any address it wants and doesn't
have to worry about source selection, because the default selection is
good enough.

This is a very, very common issue for UDP daemons.  For example, it's
an issue that affects DNS servers and RIP.

-- 
James Carlson, Solaris Networking              <[email protected]>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677
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