SNMP conntrack module a la netbios_ns

[Tim Waugh <twaugh@redhat.com>]

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Hi,

I maintain the printing stack for Fedora and Red Hat Enterprise Linux,
and I've become aware of a need for another conntrack module very
similar to nf_conntrack_netbios_ns.

When CUPS searches for network printers it issues an SNMP broadcast
query from a random source port and to the SNMP destination port, and
waits for (unicast) replies from printers, following up each reply with
a set of unicast SNMP queries.

The problem is that the iptables rules discard the replies to the
initial broadcast query.

It looks like a conntrack module is what's needed to fix the problem,
and the netbios_ns module very nearly solves it: the only changes I can
see would be needed are the port number and the maximum number of
expected replies.

Is this something that warrants a more generic module so that code can
be shared between them, or would it be better to just copy the code and
make the changes?

Thanks,
Tim.
*/


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