Re: [net-next PATCH v5 0/3] net: reserve ports for applications usingfixed port numbers

From: Cong Wang
Date: Sat Feb 20 2010 - 20:55:50 EST


Octavian Purdila wrote:
On Saturday 20 February 2010 10:11:40 you wrote:

2) I hope you could add some documentation to show the relations
between ip_local_port_range and ip_local_reserved_ports.


How does this sound:

ip_local_reserved_ports - list of comma separated ranges
Specify the ports which are reserved for known third-party
applications. These ports will not be used by automatic port
assignments (e.g. when calling connect() or bind() with port
number 0). Explicit port allocation behavior is unchanged.

The format used for both input and output is a comma separated
list of ranges (e.g. "1,2-4,10-10" for ports 1, 2, 3, 4 and
10). Writing to the file will clear all previously reserved
ports and update the current list with the one given in the
input.

Note that ip_local_port_range and ip_local_port_range settings
are independent and both are considered by the kernel when
determining which ports are available for automatic port
assignments.

You can reserve ports which are not in the current
ip_local_port_range, e.g.:

$ cat /proc/sys/net/ipv4/ip_local_port_range
32000 61000
$ cat /proc/sys/net/ipv4/ip_local_reserved_ports
8080,9148

although this is redundant. However such a setting is useful
if later the port range is changed to a value that will
include the reserved ports.

This looks fine for me.

Thanks.

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