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Add a section on the net.inet.ip.portrange.* sysctls.

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Suggested by: Mike Harding <mvh@ix.netcom.com>
MFC after:	3 days
This commit is contained in:
Matthew Dillon 2002-08-25 18:34:48 +00:00
parent c341dbce8b
commit 78d1394010
1 changed files with 26 additions and 0 deletions
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share/man/man7/tuning.7
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@ -545,6 +545,32 @@ only effects data transmission (uploading / server-side). It does not
effect data reception (downloading).
.Pp
The
.Va net.inet.ip.portrange.*
sysctls control the port number ranges automatically bound to TCP and UDP
sockets. There are three ranges: A low range, a default range, and a
high range, selectable via an IP_PORTRANGE setsockopt() call. Most
network programs use the default range which is controlled by
.Va net.inet.ip.portrange.first
and
.Va net.inet.ip.portrange.last ,
which defaults to 1024 and 5000 respectively. Bound port ranges are
used for outgoing connections and it is possible to run the system out
of ports under certain circumstances. This most commonly occurs when you are
running a heavily loaded web proxy. The port range is not an issue
when running serves which handle mainly incoming connections such as a
normal web server, or has a limited number of outgoing connections such
as a mail relay. For situations where you may run yourself out of
ports we recommend increasing
.Va net.inet.ip.portrange.last
modestly. A value of 10000 or 20000 or 30000 may be reasonable. You should
also consider firewall effects when changing the port range. Some firewalls
may block large ranges of ports (usually low-numbered ports) and expect systems
to use higher ranges of ports for outgoing connections. For this reason
we do not recommend that
.Va net.inet.ip.portrange.first
be lowered.
.Pp
The
.Va kern.ipc.somaxconn
sysctl limits the size of the listen queue for accepting new TCP connections.
The default value of 128 is typically too low for robust handling of new