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Re: Patch to implement SIOCGIFINDEX
On 2/04/2013, at 12:29 PM, christos%astron.com@localhost (Christos Zoulas)
> I would only implement it for the emulation, because it suffers from TOCTOU.
Are you thinking of the fact that index numbers are reused as interfaces come
and go, or do you have something more concrete in mind?
The consumer of interfaces numbers that I have worked with most is SNMP and
unfortunately it's been a little while since I was up to my neck in this sort
of thing. IIRC SNMP allows the index numbers to change and doesn't promise
consistency from one query to the next, so this isn't a problem that needs to
be fixed for the most common usage. Good documentation should sort out any
Another issue with SNMP is that by using the AgentX protocol, it is possible to
loosely couple SNMP agent components leading to the problem where it isn't
clear how the components should agree on how to number the interfaces. Using
the kernel's own interface indexes provides an easy solution to that problem.
Knowing when those index numbers change (because interfaces have been created
or destroyed) would be useful, but maybe this information is sent on the
routing socket? I've never had a use for the routing socket, so I don't know
exactly what can be learned from it.
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