[erlang-bugs] IPv6 problems in erlang's SNMP stack

[Stefan Zegenhagen]

Dear all,


First problem: I found no easy way to pass the "inet6" socket option
into erlang's snmpa_net_if implementation to open the UDP socket in IPv6
mode. Such an option would be required to convince erlang's SNMP stack
to talk IPv6.

Second problem: when a socket is opened in IPv6 mode on real dual-stack
operating systems, it is possible to query the SNMP agent via IPv4 *AND*
IPv6 simultaneously. Sending traps to IPv6 trap receivers works as well,
but trap receivers that are configured with IPv4 addresses always fail
with an eafnosupport error. SNMP-TARGET-MIB explicitly allows trap
receivers to have different IP address types, so I would expect such a
feature to be supported.

I know that it is possible (the Linux kernel sends out IPv6 packets
addressed to "::FFFF:A.B.C.D" via IPv4). I also know that there is a
portability problem, since operating systems may behave differently when
it comes to dual-stack operation details (its probably best being fixed
in the socket driver). Still, this is an important issue for us at the
moment and I guess others will face the same problem when IPv6 spreads
wider.


Kind regards,

-- 
Dr. Stefan Zegenhagen

arcutronix GmbH
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