On Sat, 1 Mar 2008, Mike Silbersack wrote:
On Sat, 1 Mar 2008, Fernando Gont wrote:
This patch changes the default ephemeral port range from 49152-65535 to
1024-65535. This makes it harder for an attacker to guess the ephemeral
ports (as the port number space is larger). Also, it makes the chances of
port number collisions smaller.
(http://www.ietf.org/internet-drafts/draft-ietf-tsvwg-port-randomization-01.txt)
There are a number of commonly used ports above 1000, such as nfs and x11. I
think OpenBSD uses 10000-65535, maybe that's a safer choice to go with.
In order to get acceptable open connection counts with 10gbps ethernet, I've
needed to run with a significantly lower starting portrange. In practice, the
following seems to do the trick for me:
sysctl net.inet.ip.portrange.first=10000
Of course, I only run into this if I also increase maxsockets:
sysctl kern.ipc.maxsockets=30000
Lowering the lower end of the ephemeral range to 10,000 would do the trick for
me, anyway.
Robert N M Watson
Computer Laboratory
University of Cambridge
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