netdev - Re: how to listen() on single IP address but very many ports?

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Date:	Sun, 20 Feb 2011 20:20:07 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Chris Friesen <chris.friesen@...band.com>
Cc:	netdev@...r.kernel.org
Subject: Re: how to listen() on single IP address but very many ports?

Le vendredi 18 février 2011 à 11:55 -0600, Chris Friesen a écrit :
> I have an application team that needs to listen() for tcp connections on
> many ports (and by many I mean pretty much all 64K ports).  However, the
> connections are short-lived, and the number of active connections at any
> given time is small.
> 
> Apparently when they tried this before on an older kernel the
> performance of the naive "open 60K sockets and call listen()" solution
> was not acceptable, so they used NAT with port mapping to direct all the
> incoming packets to a single real port.  However, they now want to add
> support for IPv6 and this solution won't work.
> 
> What's the recommended method for efficiently listening on this many
> ports?  Should I be able to efficiently listen() on that many sockets
> using epoll or similar?  If there isn't a way to do this, is there an
> equivalent IPv6 workaround?
> 
> One possible solution that came up was to implement a PORT_ANY which
> would match any incoming request that didn't already have an explicit
> listener.  Even better would be a way to bind a single listening socket
> to a range of ports.
> 
> Has anyone ever considered something like this?
> 

I really dont see how listening to 60K sockets can be "not acceptable".

It just runs OK, at exactly same speed than 1 socket, if using epoll.

Only 'problem' could be memory usage, a bit more heavy of course, but
who cares ?



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