[OSM-dev] osm2pgsql deltas

[Brett Henderson]

On Thu, Jan 21, 2010 at 3:21 AM, Steve Hill <steve at nexusuk.org> wrote:

> On Wed, 20 Jan 2010, Brett Henderson wrote:
>
>  Matt's suggestion of running under strace might be the way to go here.
>>  I've
>> never seen anything like this before.
>>
>
> Got it!
>
> For some reason, one of the threads creates a PF_INET6 socket on an
> ephemeral port, listenning on all network interfaces.  The same thread then
> creates a connection to that socket.  Due to a misconfiguration on my
> server, ip6tables was set to drop looped back IPv6 traffic, so it was
> sitting there waiting for the connection to time out.
>
> Fixing the ip6tables config to allow looped bak IPv6 traffic has resolved
> the problem.
>

Nice work!  I'll try to remember this.  I remember somebody on another list
having similar problems with osm2pgsql and IPv6 the other day ...


>
> Some odd notes:
>
> 1. This connection can't be especially important since it was able to carry
> on working just fine without the connection present.
> 2. Since it is on an ephemeral port, the socket is presumably only be used
> for internal communication between threads - as such, using a socket that is
> listenning for connections on all network interfaces seems like a really bad
> idea.  This sort of stuff should be done with unix domain sockets, not
> public network sockets.
> 3. Of course, I have no idea if Osmosis or the JVM itself is responsible
> for this. :)


It must be the JVM ...  The only socket stuff Osmosis does is making HTTP
requests, it never listens on sockets.  I'm very surprised it's listening on
all interfaces though.  I know there's some debug and profiling type ports
that Java 6 opens but I thought they were only available locally and I
(perhaps wrongly) assumed they were secured in some way (eg. You can connect
using the jconsole tool and get stats on running JVMs).  When I get a chance
I'll take a look at it, but I suspect there's no much I can do about it.
I'd be surprised if there was a security risk created by this, but who knows
...

Brett
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